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Histologic diagnosis of less well-differentiated cases of canine extramedullary plasmacytomas (CEMPs) may require immunohistochemical confirmation to discriminate these tumors from other round cells tumors including lymphoma, cutaneous histiocytoma, and amelanotic melanomas. CEMPs are characterized by widespread immunoreactivity for multiple myeloma 1 (MUM1) antigen and λ light chains, while the melanocytic marker melan-A has been reported to yield negative results. Here, 33 randomly selected CEMPs, 20 melanocytomas, and 20 malignant melanomas were immunohistochemically tested for MUM1, melan-A, and PNL2. In addition, CEMPs were examined for PAX5, E-cadherin, CD3, CD18, CD20, S100, as well as λ and κ light chain immunoreactivity. All CEMPs were characterized by labeling for MUM1 and λ light chain, as well as variable immunopositivity for the remaining antibodies. Notably, 13 cases of CEMPs (39.4%) exhibited immunolabeling for melan-A. Melanocytic tumors immunolabeled for melan-A (40/40; 100%) and PNL2 (34/40; 85%). An unexpected cytoplasmic immunoreactivity for MUM1 was observed in 2 melanocytic tumors. Summarized, MUM1 or melan-A immunomarkers alone are not sufficient to differentiate between CEMPs and amelanotic melanomas and should be part of a larger immunopanel including λ light chain, CD20, and PNL2. [ABSTRACT FROM AUTHOR]

We describe a case of unilateral sectoral pigmentation of the optic disc in a healthy 58‑year‑old female who presented with decreased vision and visual field defect in the involved eye since childhood. The patient was initially diagnosed with melanocytoma of the optic nerve given the suggestive clinical appearance. Thorough assessment with magnetic resonance imaging studies, laboratory work-ups and ophthalmic examination indicated that the pigmentation was linked to optic nerve hypoplasia. [ABSTRACT FROM AUTHOR]

A feline cutaneous melanocytic tumor in a 1‐year‐old cat is reported. The cytologic, histologic, and immunohistochemical characteristics of the pediatric feline cutaneous melanocytoma are included. A solitary, black‐colored nodule on the head was histologically diagnosed as the epithelioid type of melanocytoma. Immunohistochemically, the neoplastic melanocytes demonstrated immunoreactivity to the S100 and MelanA antibodies but not to the PNL2 antibody. Despite high mitotic counts (17/10HPFs) and a Ki67 index (33%) suggesting malignant melanoma, the patient exhibited a favorable 5‐month outcome. The mitotic activity of the neoplastic cells may not provide a reliable prediction for feline melanocytic tumors. [ABSTRACT FROM AUTHOR]

The Alentejano pig (Sus ibericus) is an autochthonous breed of swine from Portugal phylogenetically close to the Iberian breed that is known to develop melanocytic lesions. In this study, 34 melanocytic skin lesions were identified and collected from Alentejano pigs slaughtered for human consumption for further routine histologic assessment. The samples were classified into 4 age ranges: 1 (1 to 6 months), 2 (7 to 12 months) 3 (13 to 24 months), and 4 (more than 25 months). All the lesions were considered benign after the histopathological assessment, of which 52.9% and 47.1%, were classified as melanosis and melanocytomas, respectively. Regarding the age ranges, a statistical difference between the groups was observed, indicating that the probability of melanosis presentation was higher at the age range 4 and for melanocytomas at the age range 3. While no malignant lesions were observed in this study, it was concluded that benign melanocytic lesions are commonly found in Alentejano pig carcasses. Further research is necessary to accurately distinguish between malignant and benign lesions, which is crucial for official veterinarians to make decisions regarding meat approval or condemnation.

Purpose Methods Results Conclusion To describe the clinical features surgical technique, early and long‐term outcome with or without surgery, and histopathological findings of melanocytic anterior uveal lesions in young dogs.Medical records of dogs at a guide dog facility removed from training due to a pigmented iris lesion were reviewed from 2014 to 2021. Selected dogs had surgical iridectomies performed.Iridal melanocytic lesions were characterized as well‐delineated, pigmented, and flat (nevus) or raised (mass) lesions of the iris. Forty dogs (18 Labrador retrievers, 18 German shepherd dogs, 1 Golden retriever, 3 Labrador/Golden mixes) ranging from 0.5 to 3.1 years of age were affected unilaterally (n = 35) or bilaterally (n = 5). Sector iridectomy was performed in 13 dogs with prominent and well‐isolated mass lesion and enucleation was carried out in 2 dogs with extensive lesions, while all other cases were monitored without surgical intervention. Postoperative complications included dyscoria (13/13), focal posterior synechia (9/13) and focal nonprogressive cataract (8/13). All eyes remained visual and comfortable up to 6.2 years post‐iridectomy with no clinically identifiable local recurrence. Histopathology was consistent with uveal melanocytoma in all samples obtained surgically. All cases that did not undergo surgery remained free of complications up to 4.5 year post diagnosis.Melanocytic anterior uveal lesions may be overrepresented in certain lineages of breeds and be present at a young age. While none of the eyes developed complications when monitored without surgery, early surgical excision of the mass by sector iridectomy yields noteworthy functional outcome and retention of a comfortable globe. [ABSTRACT FROM AUTHOR]

The Alentejano pig (Sus ibericus) is an autochthonous breed of swine from Portugal phylogenetically close to the Iberian breed that is known to develop melanocytic lesions. In this study, 34 melanocytic skin lesions were identified and collected from Alentejano pigs slaughtered for human consumption for further routine histologic assessment. The samples were classified into 4 age ranges: 1 (1 to 6 months), 2 (7 to 12 months) 3 (13 to 24 months), and 4 (more than 25 months). All the lesions were considered benign after the histopathological assessment, of which 52.9% and 47.1%, were classified as melanosis and melanocytomas, respectively. Regarding the age ranges, a statistical difference between the groups was observed, indicating that the probability of melanosis presentation was higher at the age range 4 and for melanocytomas at the age range 3. While no malignant lesions were observed in this study, it was concluded that benign melanocytic lesions are commonly found in Alentejano pig carcasses. Further research is necessary to accurately distinguish between malignant and benign lesions, which is crucial for official veterinarians to make decisions regarding meat approval or condemnation. [ABSTRACT FROM AUTHOR]

Objective s : To identify canine breeds at risk for ocular melanosis and to compare the clinical and histologic features between affected Cairn Terriers (CTs) and non‐Cairn Terriers (NCTs). Design: Relative risk (RR) analysis and retrospective cohort study of dogs histologically diagnosed with ocular melanosis. Procedures: The COPLOW archive was searched for globe submissions diagnosed with ocular melanosis. Six hundred fifty globes were included, and RR analysis was performed to identify at‐risk NCT breeds. A cohort of 360 CT and NCT globes diagnosed from 2013 to 2023 were included in the retrospective cohort study. Clinical data were collected from submission forms, medical records, and follow‐up surveys. One hundred fifty‐seven submissions underwent masked histologic review. Immunohistochemical staining for CD204 was performed to determine the predominance of melanophages in affected uvea from five NCTs. Results: At‐risk NCT breeds included the Boxer, Labrador Retriever, and French Bulldog. Glaucoma was the reported reason for enucleation in 79.4% of submissions. At enucleation, clinical features less prevalent in NCTs than CTs included pigmentary abnormalities in the contralateral eye (33.7% vs. 63.1%, p =.0008) and abnormal episcleral/scleral pigmentation in the enucleated globe (25.4% vs. 53.6%, p =.0008). Histologic involvement of the episclera was also less frequent in NCTs than in CTs (39.7% vs. 76.9%, p =.008). Concurrent melanocytic neoplasms arising in melanosis were more common in NCTs (24.4%) than CTs (3.9%). Melanophages were not predominant in any samples evaluated immunohistochemically. Conclusions: Several popular NCT breeds carry risk for ocular melanosis, and some clinicopathologic disease features may differ from those described in CTs. [ABSTRACT FROM AUTHOR]

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Purpose: The term melanocytoma was recently proposed for intermediate-stage melanocytic lesions with specific histopathologic and molecular genetic features. Prior studies have demonstrated a heightened potential for these intermediate lesions to spread to regional lymph nodes, with decreased likelihood for distant spread, when compared to melanomas. Observations: Herein we present a case of a 28-year-old male who presented with a recurrent right lower eyelid margin combined cutaneous and palpebral conjunctival pigmented lesion, ultimately classified as a melanocytoma, to highlight this new nomenclature, characteristic histopathologic and genetic findings, and prognostic implications. Conclusions: Ophthalmologists should be aware of this new cutaneous histopathologic classification system and apply to the periorbital region to improve melanocytic lesion management and surveillance.

Background: Melanocytic tumors driven by MAP2K1 in‐frame deletions are among the most recently described class of melanocytic neoplasms. The reported range of diagnoses and associated genomic aberrations in these neoplasms is wide and includes melanomas, deep penetrating melanocytomas, and pigmented epithelioid melanocytoma. However, little is known about the characteristics of these tumors, especially in the absence of well‐known second molecular "hits." Moreover, despite their frequent spitzoid cytomorphology, their potential categorization among the Spitz tumors is debatable. Materials and Methods: We conducted a retrospective search through our molecular archives to identify sequenced melanocytic tumors with MAP2K1 in‐frame deletions. We reviewed the clinical and histomorphological features of these tumors and compared them to similar neoplasms reported to date. In addition, we performed single‐nucleotide polymorphism (SNP) array testing to identify structural chromosomal aberrations. Results: Of 27 sequenced tumors, 6 (22%) showed a pathogenic MAP2K1 in‐frame deletion (with or without insertion) and were included in this series. Five (83%) were females with lesions involving the upper limb. Histopathologically, all neoplasms were compounded with plaque‐like or wedge‐shaped silhouettes, spitzoid cytomorphology, and impaired cytologic maturation. All cases showed background actinic damage with sclerotic stroma replacing solar elastosis, variable pagetoid scatter, and occasional dermal mitotic figures (range 1–2/mm2). Five cases (83%) had a small component of nevic‐looking melanocytes. Biologically, these tumors likely fall within the spectrum of unusual nevi. Five cases (83%) had a relatively high mutational burden and four (67%) showed an ultraviolet radiation signature. Four cases (67%) showed in‐frame deletion involving the p.I103_K104del locus while two cases (33%) showed in‐frame deletion involving the p.Q58_E62del locus. SNP array testing showed structural abnormalities ranging from 1 to 5 per case. Five of these cases showed a gain of chromosome 15 spanning the MAP2K1 gene locus. Discussion and Conclusion: Melanocytic tumors with MAP2K1 in‐frame deletion could represent another spectrum of melanocytic tumors with close genotypic–phenotypic correlation. They are largely characterized by a spectrum that encompasses desmoplastic Spitz nevus as shown in our series and Spitz and Clark nevus as shown by others. Evolutionary, they share many similarities with tumors with BRAF V600E mutations, suggesting they are better classified along the conventional pathway rather than the Spitz pathway despite the frequent spitzoid morphology. [ABSTRACT FROM AUTHOR]

A patient presented with melanocytoma and associated choroidal neovascular membrane with hemorrhage involving the macula. The patient was treated with monthly aflibercept (Eylea) injections with significant improvement of best corrected visual acuity. In this report, we explore the development of a choroidal neovascular membrane (CNVM) formation in a patient with melanocytoma and the effect of intravitreal aflibercept (Eylea) on disease course. Case report study used patient data obtained from examination and imaging. The patient was treated with monthly intravitreal aflibercept injections leading to complete resolution of CNVM and hemorrhage, with significant improvement of best corrected visual acuity. Awareness and proper monitoring for the sequelae of melanocytoma are important for early detection and prevention of visually threatening outcomes. In cases of melanocytoma-associated CNVM formation with large subretinal hemorrhage, intravitreal aflibercept can be an effective tool for inducing CNVM regression and allowing improvement of visual acuity.

Schwannoma is a nerve sheath tumour arising from differentiated Schwann cells, and melanocytic schwannoma (MS) is a rare variant where the Schwan cells produce melanin pigment. MS is typically associated with spinal nerve roots and there have been only ~20 reports of cutaneous or subcutaneous MS to-date in humans. In canines, there have only been two reports of MS, both associated with spinal root nerves. In this report, we describe a 7-year-old Weimaraner cross breed dog that presented with two pigmented lesions on the eyelids. The lesions were surgically removed and histological analysis revealed well-circumscribed, non-encapsulated, expansile, neoplasms that were displacing most of the dermis and adnexa. The first lesion was composed of spindloid cells arranged in short interlacing streams with large amounts of pale eosinophilic cytoplasm that sometimes contained fine melanin granules. In areas there were spindle cells arranged in verocay bodies which led to a diagnosis of MS. In contrast, the second lesion was composed of polygonal cells arranged in thick sheets with large amounts of pale eosinophilic cytoplasm that sometimes contained fine melanin granules. The diagnosis was melanocytoma (which is one of the macroscopic differential diagnoses for MS). Whilst melanocytoma is a commonly occurring cutaneous lesion in canines and surgical removal is considered curative, due to little being known about MS in dogs, the outcome remained guarded, as MS in humans has an unpredictable nature, and recurrence and metastasis have been reported.

Introduction: Leptomeningeal melanocytomas are rare tumours originating from neural crest derived melanocytes. They are usually solitary and presentation with multifocal meningeal melanocytoma is very rare and indicative of potentially more aggressive behaviour. This case report and scoping review sought to evaluate the presentation, and key radiological features that can help differentiate multifocal meningeal melanocytoma from other differentials and provide a discussion of the key management and prognostic points once these tumours are diagnosed. Case presentation: A 26 year old male presented with neck pain radiating to both shoulders and subjective weakness in left shoulder movement. MRI demonstrated a large enhancing C2–C3 intradural-extramedullary lesion with further lesions at the T7/T8 level, left cerebellopontine angle and midline suprachiasmatic region. Whilst the imaging appearances were initially thought be indicative of a phacomatosis such as NF2-related schwannomatosis, surgical excision of the cervical tumour confirmed a melanocytic tumour of leptomeningeal origin, consistent with multifocal meningeal melanocytoma. Patient made a good post-operative recovery and remains under half yearly radiological surveillance, with repeat MRI 6 months after surgery demonstrating subtle growth of the untreated intracranial and spinal lesions. Literature review and conclusions: This is the first description, to our knowledge, of a multifocal meningeal melanocytoma associated with both cerebellopontine angle and suprasellar lesions. This case and included scoping review highlight the need to consider this rare diagnosis whenever multifocal craniospinal lesions are encountered, and the need to consider aggressive management through surgical resection and adjuvant craniospinal radiotherapy once these tumours are diagnosed.

Introduction: Primary melanocytic tumors originating from CNS melanocytes are rare, with a low incidence of 0.7 cases per 10 million annually. This study focuses on primary leptomeningeal melanocytomas, emphasizing their epidemiology, clinical characteristics, and diagnostic challenges. Despite their infrequency, these tumors warrant attention due to their unique features and potential for local recurrence.Case Report: A 32-year-old female presented with syncope and seizures, leading to the discovery of two left-sided supratentorial lesions initially misidentified as convexity meningiomas. Detailed imaging suggested meningioma-like features, but intraoperative findings revealed unexpected hyperpigmented lesions. Histopathological examination, supported by immunohistochemistry, confirmed primary leptomeningeal melanocytoma. The surgical approach and subsequent management are discussed.Discussion: The discussion emphasizes challenges in diagnosing primary leptomeningeal melanocytomas. Treatment debates, especially regarding adjuvant radiotherapy, are explored. Recurrence risks stress the importance of vigilant follow-up, advocating for complete surgical resection as the primary approach. The rarity of supratentorial cases adds complexity to diagnosis, necessitating a multidisciplinary approach. Insights from this case contribute to understanding and managing primary leptomeningeal melanocytomas, addressing challenges in differentiation from more common tumors and prompting ongoing research for refined diagnostics and optimized treatments.Conclusion: This study contributes insights into primary leptomeningeal melanocytomas, highlighting their rarity in supratentorial regions. The case underscores the importance of a multidisciplinary approach, incorporating clinical, radiological, and histopathological expertise for accurate diagnosis and tailored management. Ongoing research is crucial to refine treatment strategies, enhance prognostic precision, and improve outcomes for individuals with this uncommon CNS neoplasm.

Meningeal melanocytomas are rare, benign tumours of the central nervous system arising from the melanocytes of the leptomeninges. First-line treatment consists of either gross or subtotal resection with or without radiotherapy. However, given the sensitive locations of these tumours, alternative treatment options such as definitive radiotherapy may be warranted in patients deemed high-risk or without accessible tumours. A 67-year-old male presenting with spastic gait, frequent falls, and vertical gaze palsy was diagnosed with a 2.4 cm primary meningeal melanocytoma arising from the interpeduncular fossa. Given the critical tumour position within the brainstem, definitive radiotherapy was recommended. He received fractionated stereotactic radiotherapy (FSRT) to a total dose of 54 Gy in 27 fractions, resulting in a gradual improvement in gait and ocular range of motion. Follow-up imaging over the next three years revealed largely stable disease and an increase in edema with mild upper extremity weakness that improved with steroids. He was followed for three years and expired four years after treatment due to pneumonia. For patients unable to receive surgical resection, definitive RT may provide local control with minimal morbidity. [ABSTRACT FROM AUTHOR]

A patient presented with melanocytoma and associated choroidal neovascular membrane with hemorrhage involving the macula. The patient was treated with monthly aflibercept (Eylea) injections with significant improvement of best corrected visual acuity. In this report, we explore the development of a choroidal neovascular membrane (CNVM) formation in a patient with melanocytoma and the effect of intravitreal aflibercept (Eylea) on disease course. Case report study used patient data obtained from examination and imaging. The patient was treated with monthly intravitreal aflibercept injections leading to complete resolution of CNVM and hemorrhage, with significant improvement of best corrected visual acuity. Awareness and proper monitoring for the sequelae of melanocytoma are important for early detection and prevention of visually threatening outcomes. In cases of melanocytoma-associated CNVM formation with large subretinal hemorrhage, intravitreal aflibercept can be an effective tool for inducing CNVM regression and allowing improvement of visual acuity. [ABSTRACT FROM AUTHOR]

Pigmented epithelioid melanocytomas (PEM) are intermediate-grade melanocytic lesions with frequent lymph node involvement and rare metastases that tend to follow an indolent course with a favorable outcome. We report two unique cases of congenital PEM with PRKCA fusion transcripts: a multifocal PEM with an aggressive incompletely resectable scalp tumor and a solitary palmar PEM with newly reported ITGB5-PRKCA fusion. Through these case reports and a summary of previously reported cases, we outline the spectrum of disease of PEM and highlight the key clinical and histopathologic features associated with PEM with PRKCA fusion transcripts. We also discuss the treatment options and suggest that surgical excision without further adjuvant systemic treatment is reasonable first-line therapy given the favorable prognosis. [ABSTRACT FROM AUTHOR]

Resumen: Con el desarrollo de la enfermedad molecular, el diagnóstico y la comprensión de los tumores melanocíticos ha experimentado un avance descomunal en los últimos años. Esto ha significado la aparición de conceptos de difícil asimilación en el mundo clínico, el cual no está siempre en contacto directo con las técnicas genéticas de laboratorio. Al mismo tiempo, sin embargo, al clínico se le está exigiendo una terapéutica basada en muchas ocasiones en los hallazgos moleculares más recientes de un tumor melanocítico. El presente artículo explora los conceptos moleculares más recientes de la clasificación en rutas patogénicas de los tumores melanocíticos, incluidas las formas intermedias conocidas como melanocitomas, y repasa las técnicas auxiliares usadas en el estudio de estos tumores, discutiendo los resultados más complejos, sus limitaciones, y sus solapamientos. Abstract: The advent of molecular pathology has fueled unprecedented advances in the diagnosis and understanding of melanocytic tumors. These advances, however, have also generated concepts that may be difficult to grasp for clinical practitioners, who are not always conversant with the array of genetic techniques employed in the laboratory. These same practitioners, however, are being increasingly called on to provide treatments that are often based on the latest molecular findings for melanocytic tumors. We review the most recent concepts in the pathway classification of melanocytic tumors, including intermediate lesions known as melanocytomas. We examine the genetic and molecular techniques used to study these tumors, look at where they overlap, and discuss their limitations and some of the most difficult-to-interpret results.

Abstract Background To describe the correlation between standardized A-scan echography and histopathology in a ciliary body melanocytoma. Case presentation We present a case of a large ciliary body melanocytoma with significant growth, vision loss, and elevated intraocular pressure that was diagnosed clinically as a melanoma, but the standardized A-scan findings correlated to the histopathological description of a melanocytoma with multiple pseudocysts. Conclusions The reflectivity of this melanocytoma by standardized A-scan was consistent with multiple pseudocysts on pathological evaluation. This echographic pattern guided the differential diagnosis. Standardized A-scan is an important diagnostic tool in the differentiation of ciliary body melanocytomas from melanomas.

Background: Melanocytoma is a rare pigmented central nervous tumor. In the spine, it may develop in meninges, extramedullary or intramedullary. It usually has good outcome after total excision. Case report: A 40-year-old male patient was admitted to our hospital 12 years ago with a 3-month history of progressive neck pain and difficulty walking. On clinical examination, he showed upper dorsal bilateral gray blue hyperpigmentation, quadriparesis and bilateral hypoesthesia below C4. Cervical magnetic resonance imaging (MRI) T1-weighted images without contrast showed a C3-C4 intradural, extramedullary lesion. The patient underwent total microsurgical resection of the lesion. Histological and immunohistochemical analyses confirmed the diagnosis of melanocytoma. Another skin biopsy of the abnormal area showed histological findings of a blue skin nevus. Eight years after resection the patient presented with recurrent symptoms, which were similar to his initial presentation. Cervical MRI showed an intradural extramedullary tumor anterior to the spinal cord at the same C3-C4 level. The patient underwent a second complete tumor excision and melanocytoma was confirmed histologically. The patient significantly improved and remained well at last follow-up. Conclusions: Intradural extra- or intramedullary melanocytoma is a rare benign tumor that frequently recurs but usually has good outcome following total excision. [ABSTRACT FROM AUTHOR]

Background: To describe the correlation between standardized A-scan echography and histopathology in a ciliary body melanocytoma. Case presentation: We present a case of a large ciliary body melanocytoma with significant growth, vision loss, and elevated intraocular pressure that was diagnosed clinically as a melanoma, but the standardized A-scan findings correlated to the histopathological description of a melanocytoma with multiple pseudocysts. Conclusions: The reflectivity of this melanocytoma by standardized A-scan was consistent with multiple pseudocysts on pathological evaluation. This echographic pattern guided the differential diagnosis. Standardized A-scan is an important diagnostic tool in the differentiation of ciliary body melanocytomas from melanomas. [ABSTRACT FROM AUTHOR]

Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion (CMCT) is a recently described entity with only 13 cases reported in the literature. Histopathologically, the neoplasm consists of atypical epithelioid to spindled cells that form a well‐circumscribed nodule usually confined to the dermis and subcutis with cytological features including large vesicular nuclei with prominent nucleoli and abundant eosinophilic cytoplasm. Immunohistochemistry shows variable expressivity of melanocytic markers. Currently, there are limited data regarding long‐term outcomes of this newly described entity. Most cases have done well, but there is one case reported with an adverse event. Hence, further studies are needed to accurately classify this tumor. Definitive diagnosis is made by laboratory evidence of CMCT. Herein, we report the first case of CMCT with epidermal involvement in the youngest patient known to be affected to date. [ABSTRACT FROM AUTHOR]

To analyze the genetic features of melanocytomas and melanomas of the anterior uvea and assess the value of molecular testing for diagnosis and prognostication. Retrospective case-control study. Patients with melanocytoma (n = 16) and melanoma (n = 19) of the anterior uvea. Targeted next-generation sequencing was performed on formalin-fixed, paraffin-embedded tumor tissue from anterior uveal melanocytic tumors and correlated with clinicopathologic features. Presence or absence of accompanying oncogenic alterations beyond GNAQ / GNA11 and their association with histologic features and local recurrence. Hotspot missense mutations in GNAQ / GNA11 were identified in 91% (32/35) of all cases. None of the melanocytomas with or without atypia demonstrated chromosomal imbalances or additional oncogenic variants beyond GNAQ mutation, and none recurred over a median follow-up of 36 months. Additional alterations identified in a subset of melanomas include mutations in BAP1 (n = 3), EIF1AX (n = 4), SRSF2 (n = 1), PTEN (n = 1), and EP300 (n = 1); monosomy 3p (n = 6); trisomy 6p (n = 3); trisomy 8q (n = 2); and an ultraviolet mutational signature (n = 5). Local recurrences were limited to melanomas, all of which demonstrated oncogenic alterations in addition to GNAQ / GNA11 (n = 5). A single melanoma harboring GNAQ and BAP1 mutations and monosomy 3 was the only tumor that metastasized. In this study, anterior segment uveal melanocytomas did not display oncogenic alterations beyond GNAQ / GNA11. Therefore, they are genetically similar to uveal nevi rather than uveal melanoma based on their molecular features known from the literature. Molecular testing can be performed on borderline cases to aid risk stratification and clinical management decisions. [ABSTRACT FROM AUTHOR]

Abstract Objective Gross, histopathological, and immunohistochemical characteristics of uveal melanocytic neoplasms in dogs and cats were investigated. Samples Thirty‐two enucleated globes with uveal melanocytic neoplasms, 27 from dogs and 5 from cats, were examined. Procedures Morphological characteristics of uveal melanocytic neoplasms in dogs and cats were evaluated with anti‐PNL2, anti‐Melan‐A, anti‐Ki‐67, anti‐caspase‐3, and anti‐BAP1 immunomarkers. Statistical analysis was performed to compare canine melanocytomas and melanomas. Results The 32 uveal neoplasms were classified as melanocytomas (19/27 in dogs) or melanomas (8/27 in dogs, 5/5 in cats). Most tumours (84%) were located in the anterior uvea. Neoplastic cells were classified as epithelioid, spindle‐shaped, mixed, or special type (balloon and signet ring cells). The percentage of cells with melanin, melanin concentration within cells, anisocytosis and anisokaryosis, mitotic count, lymphocytic inflammation, necrosis, vascular invasion, and glaucoma were also characterized. Anisocytosis, percentage of neoplastic cells with melanin, mitotic count, and indices (proliferation and apoptotic) varied significantly between canine uveal melanomas and melanocytomas; in general, melanomas had greater cell variability, were less pigmented, and had a higher mitotic count. The melanocytic origin of the neoplasms was confirmed by positive anti‐PNL2 immunolabelling (29/32) and positive anti‐Melan‐A immunolabelling (3/32). In canine uveal melanomas, anisocytosis and anisokaryosis correlated with less pigmentation and minimal pigmentation correlated with a high percentage of immunolabelling for caspase‐3. Conclusions Uveal melanocytomas were more common in dogs, and uveal melanomas were more frequent in cats. Anisocytosis, percentage of neoplastic cells with melanin, and mitotic count are important histologic characteristics of malignancy to evaluate in uveal melanocytic neoplasms. The proliferation and apoptotic indices are relevant when comparing malignant tumours with benign tumours.

The purpose of the study was to monitor a 6-year-old optic disc melanocytoma.Patient and methods. A clinical case of optic disc melanocytoma revealed in a woman aged 28 when examining the fundus during a second pregnancy. Ophthalmological examination of the patient included clinical and hardware methods: visometry, perimetry, biomicroscopy, binocular and reverse ophthalmoscopy, ultrasound B-scanning, optical coherence tomography of optic disc and retina, fundus photorecording using fundus cameras.Results. A neoplasm of the right eye with clear boundaries is large in size, which is almost completely covers and shields the optic disc, except for a narrow strip of disc in the lower zone, heterogeneous dark brown with a high prominence in the vitreous body of 1.1 mm according to the data of ultrasonic B-scan and 1.15 according to optical coherence tomography. In the layer of nerve fibers, we can note the destruction of the retina adjacent to melanocytoma with single cystic cavities. The retinal ganglion cell complex is normal. The peripheral boundaries of the field of view of the right eye according to perimetry are normal. During the 6-year observation, we can notice 100 % visual acuity and an unchanged field of vision. Signs of slight tumor growth observed in the last year with the advent of choroidal lesion components.Conclusions. The clinical case describes unilateral melanocytoma of the optic disk of large sizes with preservation of 100 % visual acuity for 6 years of observation at low growth rates, which was found during a planned examination of the fundus of the young patient during pregnancy.

Choroidal cavitations may be rarely observed in choroidal nevi. Enhanced depth imaging optical coherence tomography is a useful tool for the detection and follow-up of these lesions. Purpose: To describe a case of choroidal nevus with intralesional cavitations detected with enhanced depth imaging optical coherence tomography and to show its changes during an 8-year follow-up. Methods: A case report. Results: A 55-year-old male patient was found to have a pigmented lesion at the posterior pole of his right eye, just temporal to the fovea. A complete multiimaging examination was obtained and showed a lesion of about 4 mm of diameter with a small amount of subretinal fluid and chronic changes in the retina overlying the lesion. Based on clinical examination, a diagnosis of choroidal nevus was made, but interestingly the enhanced depth imaging optical coherence tomography revealed the presence of intralesional cavitations. Close follow-up with no intervention was planned, and over 8 years of observation, the lesion remained stable in size, with a gradual increase of the central necrosis. Conclusion: Benign pigmented choroidal lesions can show internal cavitations likely secondary to internal necrosis. This feature does not represent a sign of malignancy of the lesion. Enhanced depth imaging optical coherence tomography is a feasible imaging tool for the visualization of the internal cavitations and to follow their evolution over time. [ABSTRACT FROM AUTHOR]

Simple Summary: Oncept is a vaccine that is used to treat melanoma, a cancer of pigmented cells that can spread throughout the body, in dogs and other veterinary species. Its use is controversial, however, as the results of studies have been mixed as to whether it provides benefit and increases lifespan when used. This review summarizes the history of Oncept, and the various scientific studies that have reported on its use in dogs and other animals. While the vaccine appears to be safe, there does not appear to be evidence that it improves outcome when used. Further studies to better evaluate its use in patients, and exploration of other treatment options for melanoma, need to be performed. The Oncept melanoma vaccine is xenogeneic DNA vaccine targeting tyrosinase. It is USDA approved for treatment of stage II to III canine oral melanoma and is also used off-label for melanomas arising in other locations and in other species. While the vaccine appears safe, the published data is mixed as to whether it provides a survival benefit, and the use of the vaccine is somewhat controversial in the veterinary oncology community. In this paper, the published literature describing the use of Oncept is reviewed and evaluated. [ABSTRACT FROM AUTHOR]

The role of stereotactic radiosurgery (SRS) in the management of recurrent and residual intracranial primary melanocytomas (PMC) remains unclear. The aim of this study is to evaluate the safety and efficacy of SRS in the management of these rare tumors. One patient treated with SRS in our institution for an intracranial PMC was retrospectively identified. Additionally, a systematic review of English articles using MEDLINE was performed to identify studies reporting on treatment and tumor characteristics and patient outcomes following SRS-management of intracranial PMC. Including our institution's patient, a total of 13 patients (11 male and 2 female) met the inclusion criteria and were analyzed. The median age at SRS treatment was 49 years (interquartile range [IQR] 27). At a median follow-up of 24 (IQR 48) months, the aggregate local tumor-control rate was 76.9%. Progression occurred in 3 patients and was managed with repeat SRS (1 of 13) or salvage resection (2 of 13). One case of malignant transformation to melanoma leading to leptomeningeal dissemination and death was noted. SRS appears to be a reasonable treatment option for recurrent and residual melanocytomas. A higher prescription dose might be reasonable in the treatment of intermediate grade or recurring PMC. Close longitudinal follow-up for recurrence or malignant transformation of melanocytomas after SRS is recommended. [ABSTRACT FROM AUTHOR]

Objective: Gross, histopathological, and immunohistochemical characteristics of uveal melanocytic neoplasms in dogs and cats were investigated. Samples: Thirty‐two enucleated globes with uveal melanocytic neoplasms, 27 from dogs and 5 from cats, were examined. Procedures: Morphological characteristics of uveal melanocytic neoplasms in dogs and cats were evaluated with anti‐PNL2, anti‐Melan‐A, anti‐Ki‐67, anti‐caspase‐3, and anti‐BAP1 immunomarkers. Statistical analysis was performed to compare canine melanocytomas and melanomas. Results: The 32 uveal neoplasms were classified as melanocytomas (19/27 in dogs) or melanomas (8/27 in dogs, 5/5 in cats). Most tumours (84%) were located in the anterior uvea. Neoplastic cells were classified as epithelioid, spindle‐shaped, mixed, or special type (balloon and signet ring cells). The percentage of cells with melanin, melanin concentration within cells, anisocytosis and anisokaryosis, mitotic count, lymphocytic inflammation, necrosis, vascular invasion, and glaucoma were also characterized. Anisocytosis, percentage of neoplastic cells with melanin, mitotic count, and indices (proliferation and apoptotic) varied significantly between canine uveal melanomas and melanocytomas; in general, melanomas had greater cell variability, were less pigmented, and had a higher mitotic count. The melanocytic origin of the neoplasms was confirmed by positive anti‐PNL2 immunolabelling (29/32) and positive anti‐Melan‐A immunolabelling (3/32). In canine uveal melanomas, anisocytosis and anisokaryosis correlated with less pigmentation and minimal pigmentation correlated with a high percentage of immunolabelling for caspase‐3. Conclusions: Uveal melanocytomas were more common in dogs, and uveal melanomas were more frequent in cats. Anisocytosis, percentage of neoplastic cells with melanin, and mitotic count are important histologic characteristics of malignancy to evaluate in uveal melanocytic neoplasms. The proliferation and apoptotic indices are relevant when comparing malignant tumours with benign tumours. [ABSTRACT FROM AUTHOR]

A 9-y-5-mo-old, spayed female, mixed-breed dog with buphthalmia and elevated intraocular pressure in the left eye, consistent with glaucoma, was evaluated. Black-pigmented, slightly elevated tissue with irregular margins was noted on the dorsolateral aspect of the left globe. Ultrasonography detected a mass, later identified as lacrimal gland, adjacent to the globe and the thickened uvea. The surgically removed lacrimal gland was effaced by dense sheets of melanin-laden cells. Within the enucleated globe, numerous melanin-laden cells infiltrated and expanded the rostral two-thirds thickness of the cornea, the entire anterior uvea (iris and ciliary body), and a rostral portion of the choroid. Melanin-laden cells in the left lacrimal gland and globe showed no nuclear atypia or mitotic figures, and reacted to anti-S100 and anti–melan A antibodies by immunohistochemistry. Our final diagnosis was concurrent lacrimal gland melanocytoma and ocular melanocytosis. The trabecular meshwork of the eye was obliterated by melanin-laden cells, which was the likely cause of glaucoma in this patient. To our knowledge, melanocytoma affecting the lacrimal gland has not been reported previously in a non-human mammalian species. Veterinary clinicians are encouraged to include melanocytoma in the differential list when examining an enlarged lacrimal gland. [ABSTRACT FROM AUTHOR]

Choroidal melanoma is a malignant tumor prone to early metastasis. Its clinical picture is polymorphic, as a result of which it can simulate many diseases of the fundus, which are referred to in the literature as pseudomelanomas. Among these are: choroidal nevus, localized choroidal hemangioma, melanocytomas, choroidal metastatic carcinoma, congenital hypertrophy of retinal pigment epithelium, late stage of age-related macular degeneration, focal retinal choroiditis, organized subretinal hemorrhage, retinal hemangiomas. However, studies comparing the clinical signs of all listed pseudomelanomas and small choroidal melanoma are few. The first part of the review describes the ophthalmoscopic picture of the small choroidal melanoma and pseudomelanomas.

Meningeal melanocytoma is a rare benign tumor, most frequently located in the posterior fossa and spinal canal. Localized tumors present as leptomeningeal masses and range from well-differentiated melanocytomas to lesions of intermediate malignancy and overtly malignant melanomas. Spinal meningeal melanocytoma has a benign course and is amenable for gross total resection. The outcome is favorable following complete resection. Meningeal melanocytoma may occasionally be associated with histological benign leptomeningeal spread and aggressive clinical course in spite of the absence of malignant transformation. We report a case of intraspinal melanocytoma in a 57-year-old female, which clinically as well as radiologically mimicked other spinal lesions. The final diagnosis was confirmed on histopathology. [ABSTRACT FROM AUTHOR]

Cutaneous intermediate melanocytic neoplasms with ambiguous histopathological features are diagnostically challenging. Ancillary cytogenetic techniques to detect genome-wide copy number variations (CNVs) might provide a valuable tool to allow accurate classification as benign (nevus) or malignant (melanoma). However, the CNV cut-off value to distinguish intermediate lesions from melanoma is not well defined. We performed a systematic review and individual patient data meta-analysis to evaluate the use of CNVs to classify intermediate melanocytic lesions. A total of 31 studies and 431 individual lesions were included. The CNV number in intermediate lesions (median 1, interquartile range [IQR] 0–2) was significantly higher (p<0.001) compared to that in benign lesions (median 0, IQR 0–1) and lower (p<0.001) compared to that in malignant lesions (median 6, IQR 4–11). The CNV number displayed excellent ability to differentiate between intermediate and malignant lesions (0.90, 95% CI 0.86–0.94, p<0.001). Two CNV cut-off points demonstrated a sensitivity and specificity higher than 80%. A cut-off of ≥3 CNVs corresponded to 85% sensitivity and 84% specificity, and a cut-off of ≥4 CNVs corresponded to 81% sensitivity and 91% specificity, respectively. This individual patient data meta-analysis provides a comprehensive overview of CNVs in cutaneous intermediate melanocytic lesions, based on the largest pooled cohort of ambiguous melanocytic neoplasms to date. Our meta-analysis suggests that a cut-off of ≥3 CNVs might represent the optimal trade-off between sensitivity and specificity in clinical practice to differentiate intermediate lesions from melanoma. [ABSTRACT FROM AUTHOR]

Purpose: To describe the clinical and histopathological features of a case of choroidal melanocytoma treated by local resection. Observations: A 73-year-old man was referred to our hospital with a clinical diagnosis of choroidal melanoma. His best corrected visual acuity at presentation was 20/20 OU. Ocular fundus examination of his right eye showed a pigmented intraocular tumor. Local resection of the tumor was performed under general anesthesia. Histopathological examination of the excised tumor showed proliferation of round to ovoid cells with abundant cytoplasm containing many melanosomes and uniform nuclei and these histopathological findings were compatible with a diagnosis of choroidal melanocytoma. Visual acuity of 20/200 OD has been maintained for over 4 years without local recurrence. Conclusions and Importance: Clinical diagnosis of choroidal melanocytoma, especially differentiation from melanoma, is difficult and challenging. Local resection of the tumor allowed study of the histopathological features of the choroidal melanocytoma and maintained tolerable vision in the current case.

The Oncept melanoma vaccine is xenogeneic DNA vaccine targeting tyrosinase. It is USDA approved for treatment of stage II to III canine oral melanoma and is also used off-label for melanomas arising in other locations and in other species. While the vaccine appears safe, the published data is mixed as to whether it provides a survival benefit, and the use of the vaccine is somewhat controversial in the veterinary oncology community. In this paper, the published literature describing the use of Oncept is reviewed and evaluated.

The “multidimensional” World Health Organization (WHO) classification 2018 of melanocytic tumors encompasses nine melanoma pathways (seven of which for cutaneous melanoma) according to a progression model in which morphologically intermediate melanocytic tumors are cosidered as simulators and/or precursors to melanoma. These “intermediates” can be subclassified into: i) a “classical” subgroup (superficial/thin compound: dysplastic nevus), which is placed within the morphologic and molecular progression spectrum of classical (Clark’s and McGovern’s) melanoma subtypes (superficial spreading and, possibly, nodular); and ii) a “non-classical” subgroup (thick compound/dermal: “melanocytomas”) whose genetic pathways diverge from classical melanoma subtypes. Such a progression model is aimed at giving a conceptual framework for a histopathological classification; however, routine clinicopathological practice strongly suggests that most melanomas arise de novo and that the vast majority of nevi are clinically stable or even involuting over time. Clinicopathological correlation can help identify some severely atypical but benign tumors (e.g.: sclerosing nevus with pseudomelanomatous features) as well as some deceptively bland melanomas (e.g.: lentiginous melanoma; nested melanoma), thereby addressing some ambiguous cases to a correct clinical management. The recently available adjuvant therapy regimens for melanoma raise the problem of a careful distinction between severely atypical (high grade) melanocytoma and “classical” melanoma: conventional morphology can guide an algorithmic approach based on an antibody panel (anti-mutated BRAF, BAP1, PRAME, ALK, TRKA, MET, HRAS-WT, ROS; beta catenin; R1alpha; p16; HMB45; Ki67), a first-line molecular study (identification of hot spot mutations of BRAF and NRAS) and an advanced molecular study (sequencing of NF1, KIT, BRAF, MAP2K1, GNAQ, GNA11, PLCB4, CYSLTR2, HRAS; fusions studies of BRAF, RET, MAP3K8, PRKCA); as a final step, next-generation sequencing can identify melanocytic tumors with rare genetic signatures and melanocytic tumors with a high tumor mutation burden which should be definitely ascribed to the category of classical melanoma with the respective therapeutic options.

The "multidimensional" World Health Organization (WHO) classification 2018 of melanocytic tumors encompasses nine melanoma pathways (seven of which for cutaneous melanoma) according to a progression model in which morphologically intermediate melanocytic tumors are cosidered as simulators and/or precursors to melanoma. These "intermediates" can be subclassified into: i) a "classical" subgroup (superficial/thin compound: dysplastic nevus), which is placed within the morphologic and molecular progression spectrum of classical (Clark's and McGovern's) melanoma subtypes (superficial spreading and, possibly, nodular); and ii) a "non-classical" subgroup (thick compound/dermal: "melanocytomas") whose genetic pathways diverge from classical melanoma subtypes. Such a progression model is aimed at giving a conceptual framework for a histopathological classification; however, routine clinicopathological practice strongly suggests that most melanomas arise de novo and that the vast majority of nevi are clinically stable or even involuting over time. Clinicopathological correlation can help identify some severely atypical but benign tumors (e.g. : sclerosing nevus with pseudomelanomatous features) as well as some deceptively bland melanomas (e.g. : lentiginous melanoma; nested melanoma), thereby addressing some ambiguous cases to a correct clinical management. The recently available adjuvant therapy regimens for melanoma raise the problem of a careful distinction between severely atypical (high grade) melanocytoma and "classical" melanoma: conventional morphology can guide an algorithmic approach based on an antibody panel (anti-mutated BRAF, BAP1, PRAME, ALK, TRKA, MET, HRAS-WT, ROS; beta catenin; R1alpha; p16; HMB45; Ki67), a first-line molecular study (identification of hot spot mutations of BRAF and NRAS) and an advanced molecular study (sequencing of NF1, KIT, BRAF, MAP2K1, GNAQ, GNA11, PLCB4, CYSLTR2, HRAS ; fusions studies of BRAF, RET, MAP3K8, PRKCA); as a final step, next-generation sequencing can identify melanocytic tumors with rare genetic signatures and melanocytic tumors with a high tumor mutation burden which should be definitely ascribed to the category of classical melanoma with the respective therapeutic options. [ABSTRACT FROM AUTHOR]

"Cutaneous melanocytic tumor with CRTC1‐TRIM11 fusion" (CMTCT) is a newly described, potentially novel entity that typically presents as a dermal nodule on the head and neck, extremities, and trunk of adults. Histopathologically, it is reported as a nodular or multinodular tumor composed of epithelioid and spindle cells that are variably immunoreactive for S100‐protein, SOX10, and MITF along with more specific melanocytic markers such as MelanA and HMB45. With only 11 cases reported in the English literature so far, the neoplasm appears to behave in a relatively indolent fashion. Nevertheless, in one case, local recurrence and synchronous distant metastasis were evident after 13 years. Additional cases with longer follow‐up are essential to determine the neoplasm's biologic behavior with more accuracy. Herein, two cases of CMTCT, one arising on the lower back of a 65‐year‐old female and the other on the arm of a 33‐year‐old female in addition to a comprehensive literature review are reported. [ABSTRACT FROM AUTHOR]

The recent WHO classification of skin tumors has underscored the importance of acknowledging intermediate grade melanocytic proliferations. A multistep acquisition of oncogenic events drives the progressive transformation of nevi into melanomas. The various pathways described are modulated by the initial oncogenic drivers that define the common, blue, and Spitz nevi groups. Intermediate lesions are most often the result of a clonal evolution within such nevi. Based on this established classification, we have suggested for each pathway a practical diagnostic approach, benefiting from the recently developed molecular tools, both in the setting of general pathology labs and expert centers. Moreover, recommendations regarding the re-excision and clinical follow-up are given to support decision-making in multidisciplinary tumor boards. [ABSTRACT FROM AUTHOR]

Background: Intramedullary melanocytomas are exceedingly rare and their management is largely based on case reports and small clinical series. They have characteristic imaging and histologic findings that can aid in their diagnosis. Genetic testing may be required for definitive diagnosis and management guidance in ambiguous cases. Case Description: We present the case of a thoracic intramedullary meningeal melanocytoma in a patient unable to undergo an MRI. Conclusion: This is the first reported S-100-negative case with genetic testing to support the diagnosis of a rare intramedullary melanocytoma. [ABSTRACT FROM AUTHOR]

Melanocytoma is a deeply pigmented variant of melanocytic nevus that classically occurs in the optic disk, sometimes with contiguous involvement of the adjacent retina or choroid. Historically, this tumor was often confused with malignant melanoma both clinically and histopathologically. Today, however, it is generally recognized by its typical clinical features that differ from most melanomas and erroneous enucleation is rarely done. Histopathologically, melanocytoma is composed of intensely pigmented round to oval nevus cells with benign features. Although traditionally believed to be a relatively stationary lesion, it is now known to exhibit minor enlargement in 10--15% of cases and can cause minor visual loss by a variety of mechanisms. In rare instance, it can induce severe visual loss due to spontaneous necrosis of the lesion or compressive optic neuropathy. More importantly, it can exhibit malignant transformation into melanoma in 1--2% of cases. Ophthalmologists should be familiar with melanocytoma of the optic disk and affected patients should be followed periodically.

To evaluate the distribution of the PAX8 transcription factor protein in ocular tissues and to investigate if immunohistochemical stains for this biomarker are useful in the diagnosis of intraocular tumors. Observational case series. Excision and cytologic analysis specimens of 6 ciliary body epithelial neoplasms, 2 iris epithelial neoplasms, 3 retinal pigment epithelial neoplasms, 3 intraocular medulloepitheliomas, 15 uveal melanomas, and 5 uveal melanocytomas. Hematoxylin–eosin and PAX8 immunohistochemical stains were performed on all specimens. In appropriate cases, bleached preparations and other immunohistochemical stains, including AE1/AE3 cytokeratin, Lin28A, and CD45, were performed. Distribution of PAX8 expression in normal and neoplastic tissue. Strong nuclear PAX8 expression was observed in the normal corneal epithelium, iris sphincter pupillae muscle, iris pigment epithelium and dilator muscle complex, nonpigmented and pigmented epithelia of the ciliary body, lens epithelium, and a subset of retinal neurons. The normal retinal pigment epithelium and uveal melanocytes did not stain for PAX8. The ciliary body epithelial and neuroepithelial tumors (adenoma, adenocarcinoma, and medulloepithelioma) showed uniform strong nuclear PAX8 immunoreactivity. All melanocytic tumors (iris melanoma, ciliary–choroidal melanoma, and melanocytoma) and retinal pigment epithelial neoplasms showed negative results for PAX8. A subset of tumor-associated lymphocytes, most prominent in uveal melanoma, showed positive results for PAX8. The uniformity of the PAX8 staining was superior to the variable cytokeratin staining in the ciliary epithelial neoplasms and the variable Lin28A staining in malignant medulloepithelioma. The veracity of PAX8 staining was equally as robust on cytologic analysis and open-flap biopsy specimens of ciliary epithelial and iris epithelial neoplasms, melanocytoma, and melanoma. PAX8 has proven to be a very useful diagnostic marker in a select group of adult intraocular tumors, and we highly recommend its inclusion in diagnostic antibody panels of morphologically challenging intraocular neoplasms. [ABSTRACT FROM AUTHOR]

Melanocytomas of the central nervous system are rare benign or intermediate grade localized melanocytic tumors. Despite its benign nature, it can follow a locally aggressive course with propensity to recur. We present the case of a 29 years old female who presented with a recurrent lesion in cervical spine and rapidly progressing quadriparesis. On examination, there was loss of power in right-sided extremities and reduction in sensations in left-sided extremities. Magnetic resonance imaging spine revealed a homogeneously enhancing intradural extramedullary dumbbell-shaped mass lesion at C4/5 level with extension through right C4 neural foramina to the extraforamina space, causing severe spinal cord compression. Intraoperatively, bluish-colored tumor was identified along with underlying hematoma. Gross total excision of the tumor was done. Tumor was received in the histopathology department in multiple black-colored fragments. Microscopically, a heavily pigmented tumor was seen with the sheets and nodules of polygonal cells with large nuclei and prominent nucleoli. Differentials considered were meningeal melanocytoma and malignant melanoma. On immunohistochemistry, the tumor cells showed diffuse positivity for HMB 45 and S100. Ki 67 index was around 1%. On radiological review, the tumor was fairly well circumscribed and did not infiltrate the adjacent tissues. There was no evidence of any lesions elsewhere in the body. Considering these features, the tumor was diagnosed with meningeal melanocytoma. Postoperatively, there was significant immediate improvement in quadriparesis and patient could walk with minimal support. [ABSTRACT FROM AUTHOR]

Abstract Background Meningeal melanocytoma is a rare pigmented tumor arising from leptomeningeal melanocytes. Patients with this tumor might initially consult a dentist because a mass lesion in Meckel’s cave could manifest as dental pain and malocclusion, thereby mimicking temporomandibular disorder. The diagnostic approach, especially using imaging modalities, would be challenging in such cases unless an interdisciplinary approach is used. Case presentation Here, we report a case of a 39-year-old Japanese man who had a history of pain and numbness on the left side of his face and malocclusion for 3 months before the initial visit. The diagnosis was primary intracranial meningeal melanocytoma arising from Meckel’s cave. Conclusions The process by which the final diagnosis of meningeal melanocytoma was reached highlights the importance of collaboration between the medical and dental disciplines. This case also demonstrates that meningeal melanocytoma has a specific signal pattern on magnetic resonance imaging, including high signal intensity on T1-weighted images and low signal intensity on T2-weighted images.

Abstract Background Meningeal melanocytoma is considered a rare lesion arising from leptomeningeal melanocytes. Nearly two thirds of meningeal melanocytomas were reported in the intracranial compartment and the remaining one third in the spine. Spinal melanocytomas can be extradural or intradural, with extradural variant being more common, and the majority of cases have been single reports. Methods A 5-year-old male presented with a 4-month history of non-radiating low back pain persistent at rest, with otherwise non-remarkable medical history. The patient was neurologically intact with no deficits. Preoperatively, routine laboratory investigations were non-remarkable. MRI imaging was done and showed a lesion at the level of T11 to L4, hyperintense on T1 and hypointense on T2 with homogenous contrast enhancement. Intraoperatively, the lesion was hemorrhagic, brownish, and rubbery in consistency attached to the ventral dura. Microscopic picture revealed dense cytoplasmic brown melanin pigments, with no significant mitoses or nuclear atypia. What is unique about our case is the age of the patient (5 years). Results To the best of our knowledge, after reviewing the literature, this is the youngest case to be reported. Conclusions SMM is an extremely rare tumor with a benign course. Complete surgical excision should be attempted. Age of presentation may be as young as in our case and the diagnosis of such a tumor should never be excluded in this early age group with persistent low back ache.