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Desmoplastic melanoma (DM), a type of spindle cell melanoma separated into pure desmoplastic melanoma (PDM) and mixed desmoplastic melanoma (MDM) subtypes, can be a diagnostic challenge and easily confused for dermal scar, especially PDM. We report a 65‐year‐old white man who received a left thumb amputation after an initial biopsy for melanoma, an unclassified type with epithelioid morphology. The amputation and sentinel lymph node specimens were significant for residual melanoma with epithelioid morphology, dermal scar, and a slightly expanded "scar‐like" capsular area in one of seven lymph nodes, which was diffusely positive for SOX10 on reflex sentinel lymph node immunohistochemical protocol. On re‐review of the amputation "scar" like area, a subsequent SOX10 stain confirmed the diagnosis of MDM in this area with epithelioid and spindle cell morphology, significantly upgrading the tumor stage. We share this case to highlight: (i) MDM, although exceptionally uncommon, can result in a pure spindle cell lymph node metastasis, (ii) to encourage increased utilization of SOX10 to assess sentinel lymph node biopsies, especially in the context of melanomas with a spindle cell component, and (iii) share an example of inattentional blindness which was fortunately identified by reflex sentinel lymph node immunohistochemical protocols. [ABSTRACT FROM AUTHOR]

Background: Perineuriomatous nevi are rare and diagnostically problematic. We report a series of eight perineuriomatous nevi to highlight the diagnostic features. Methods: Cases were retrospectively reviewed and characterized. Results: Median age was 42.5 years (range 25‐64), with equal sex distribution. Lesions occurred on the arm (n = 4), trunk (n = 2), and head/neck (n = 2). Median size was 7.5 mm (range 5‐12 mm). Clinical differential diagnoses included atypical nevus (3), blue nevus (1), neurofibroma (1), and dermatofibroma (1). Lesions were circumscribed, dome‐shaped (5/8), and biphasic (8/8) with nested epithelioid cells and wavy spindled cells arranged in whorled fascicles in a myxocollagenous stroma. When present, junctional growth was lentiginous (4/8). No cases displayed pleomorphism or mitotic figures. The perineuriomatous component stained positively for epithelial membrane antigen (8/8 focal to diffuse) and CD34 (4/5 focal to diffuse). SOX10 and S100 protein stained all nevoid cells and in some cases a subset of intermingled spindled cells in perineuriomatous areas, where other melanocytic markers were negative. p16 protein expression was uniformly retained (3/3), and p53 negative (0/2). Nevoid cells in most lesions were positive for BRAFV600E (5/7). Ki67 was mildly elevated (~5%) in 3/3 cases. Conclusions: Recognizing the histopathologic and immunophenotypic features in these unusual nevi helps avoid overdiagnosis. [ABSTRACT FROM AUTHOR]

The development of flat pigmented lesions on chronically sun‐damaged (CSD) skin of the face may represent the clinical manifestation of a wide variety of hyperplastic/neoplastic melanocytic proliferations. We report the exceptional case of an acquired pigmented patch occurring on CSD skin, histopathologically characterized by diffuse hyperplasia of dendritic/spindled melanocytes in the superficial dermis within a widened band of actinic elastosis. This lesion was associated with a small focus of early invasive lentigo maligna melanoma (LMM). We show the melanocytic nature of the population of dermal pigmented cells by means of single and double immunohistochemical staining for melanocytic and histiocytic markers. The biologic significance of the focus of LMM within the hyperpigmented lesion (whether random collision phenomenon or causally related occurrence), as well as the pathogenesis of the whole dermal lesion are difficult to elucidate. Our case emphasizes the need for a better understanding of the pathophysiology of so‐called dermal melanocytes. [ABSTRACT FROM AUTHOR]

Background: Positive staining for SOX10 and the S100 protein are often used in the evaluation of challenging melanocytic neoplasms including melanoma in patient samples. SOX-10 positivity of non-melanocytes in re-excision specimen could complicate the evaluation of invasive melanoma with an invasive desmoplastic component. Therefore, quantifiable data regarding the positivity of SOX-10 in scars will help dermatopathologists to better identify false positive staining. Methods: A retrospective analysis was performed on 50 re-excision specimens from 2013 to 2017, with a diagnosis of squamous cell carcinoma (SCC) or squamous cell carcinoma in situ (SCCIS). Blocks of re-excision specimens containing scars were stained for SOX-10; results were evaluated by a board-certified dermatopathologist. The sum of the five highest numbers of high-power field (HPF) counts as a proxy for “SOX-10 stain factor," and cell morphological features were analyzed. MART-1 and CD68 immunohistochemical staining was performed to study possible lineage of these SOX-10 positive cells. Results: All 50 specimens showed varying degrees of SOX-10 positivity for histiocytes. SOX-10 positive histiocytes were present in 86% of re-excision scar tissues, of which 71.3% had spindle-shaped or angulated nuclei, and 61.8% had nuclear sizes larger than typical lymphocytes (7 μm). Within the same area of scars, CD68 staining was floridly positive, where as MART-1 staining was overwhelmingly negative. Conclusions: This study illustrates a potential diagnostic pitfall of using SOX-10 to evaluate re-excision specimens of melanocytic neoplasms and also suggests a previously undescribed staining pattern in scars of SOX-10 positive cells that are not melanocytes. We postulate that such SOX-10 positive cells may represent a small fraction of histiocytes routinely found in scar tissue. [ABSTRACT FROM AUTHOR]

Objective To describe the epidemiological characteristics and survival of desmoplastic melanoma of the head and neck (DMHN) and discuss the factors influencing survival variation among DMHN, DM of other sites (DMnHN), and conventional melanoma of the head and neck (CMHN). Study Design Retrospective cohort study. Setting Surveillance, Epidemiology, and End Results (SEER) database (years 1992-2013). Subjects and Methods Incidence and survival data for 1095 patients with DMHN, 1139 patients with DMnHN, and 40,257 patients with CMHN were obtained. Kaplan-Meier and Cox proportional hazards regression models were used to calculate survival outcomes. Results Patients with DMHN were diagnosed at greater Breslow thickness ( P < .001), stage ( P < .001), and Clark's level ( P < .001) compared to DMnHN and CMHN. Kaplan-Meier survival analysis demonstrated disease-specific survival (DSS) at 5 and 10 years for DMHN to be 80.5% and 74.7%, respectively, compared with 89.1% and 86%, respectively, for DMnHN and 88.1% and 83%, respectively, for CMHN (log-rank test; P < .001). On multivariate Cox regression analysis, age at diagnosis ( P < .001), Breslow depth >4.00 mm ( P = .006), lymph node status ( P < .001), and presence of ulceration ( P < .001) were found to be independent predictors of DSS for DMHN. Conclusion The increasing incidence and poor survivability of DMHN compared to DMnHN and CMHN are parsimoniously explained by the later stage of disease and depth of invasion at diagnosis, highlighting the importance of improved diagnosis and awareness of DMHN. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma ( DM) and cutaneous malignant peripheral nerve sheath tumors ( MPNST) reveal histological and immunohistochemical similarities, including S100 positivity and negative staining for conventional melanocytic markers. We present 3 cases of cutaneous S100-positive spindle cell tumors in elderly patients, in which first findings led to initial misdiagnoses as cutaneous MPNST and benign peripheral sheath nerve tumor (neurofibroma). The identification of adjacent atypical melanocytic hyperplasia in the overlying skin along with tumor cell proliferation, also in the superficial dermis, the neurotropic component and the absence of any relationship between the tumor and a major nerve, pre-existing neural benign tumor or the existence of stigmata suggestive of neurofibromatosis raised consideration of a DM. Careful attention should be paid to the presence of a firm dermal nodule and atypical scar lesions especially in sun-exposed areas (mainly head and neck region) in elderly patients associated with S100-positive spindle cell proliferation, solar elastosis and adjacent atypical melanocytic proliferation. In such cases, the possibility of a DM should be excluded with caution, especially if the tumor reveals a paucicellular morphology resembling various non-melanocytic neoplasms including malignant or benign peripheral sheath nerve tumors. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma is an uncommon form of melanoma characterized by atypical spindled melanocytes and abundant collagen deposition. It typically presents in sun-damaged skin of the elderly as an amelanotic, indurated lesion. It has a higher tendency for local recurrence but lower risk of lymph node metastasis vs. conventional malignant melanoma. We report two cases in women aged 59 and 66 who presented with small scalp lesions clinically suggestive of alopecia. The differential diagnosis included alopecia areata, lupus erythematosus and lichen planopilaris. Biopsies performed according to alopecia protocol were reviewed at our institutions. Biopsies revealed atypical spindled and nested epithelioid melanocytes set in a sclerotic dermis with scattered lymphoid aggregates and immunohistochemical expression of S100 protein, features diagnostic of combined desmoplastic melanoma. Wide local excision with skin graft was performed on the older patient. Excision showed combined desmoplastic melanoma with a Breslow thickness of 8.5 mm with melanoma in situ identified in the adjacent epidermis. The other patient sought treatment elsewhere and was lost to follow up. These cases illustrate desmoplastic melanoma as an unusual etiology and dangerous clinical pitfall in patients with scar-like alopecia. To the authors' knowledge, these represent the second and third reported cases of desmoplastic melanoma presenting as primary alopecia neoplastica. [ABSTRACT FROM AUTHOR]

To examine, in a prospective fashion, the utilization and efficacy of adjuvant radiation therapy ( RT) in patients with resected desmoplastic melanoma ( DM). Adult patients with resected, margin-negative, and nonmetastatic DM were eligible for this single-arm prospective phase II study. Patients were to receive postoperative RT, 30 Gy in five fractions, to the operative bed with 2- to 3-cm margins (depending on the tumor location). Nodal basin RT was not allowed. The primary study endpoint was the 2-year local recurrence rate ( LRR). Secondary endpoints included the incidence of regional and distant metastatic disease, progression-free survival, overall survival ( OS), and treatment-related toxicity. Twenty patients with a single de novo DM lesion meeting trial eligibility criteria were enrolled and treated. The 2-year LRR was 10%, with two patients demonstrating a LR within 2 years of completion of protocol therapy. No regional or distant failures occurred. OS at 2 and 5 years was 95 and 77%, respectively. There were no grade 3 or higher acute or late adverse events that were related to the protocol therapy. Adjuvant RT after wide local excision ( WLE) for DM is efficacious and well tolerated. It should be considered for DM patients after margin-negative WLE. Additional study is needed to further refine low-risk patient populations that can potentially have adjuvant RT omitted as part of the treatment plan. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma ( DM) is histologically characterized by a proliferation of spindle melanocytes dispersed in a collagenous stroma that can be mistaken for a variety of neoplasms. The purpose of this study was to analyze 40 cases of DM with a comprehensive panel of immunohistochemical markers ( KBA.62, p16, Ezrin, WT-1, MITF-1, SOX-10, CD117, SOX-2, nestin, PNL2, p75, MART-1, gp100 and S100p) to obtain a more complete understanding of the potential use of these antibodies in the diagnosis of DM. We found that all cases of DM expressed p16, WT-1, SOX-10, nestin and S100p and 95% of cases expressed p75. There was variable expression with Ezrin, SOX-2, KBA.62, MART-1 and HMB-45. Most DMs did not express MITF-1, PNL2 and CD117. Conditions that may enter in the histologic differential diagnosis of DM, including dermal scars, fibromatosis and dermatofibromas were also studied. Nearly all control cases also stained positive for p16 but were negative for WT1, SOX10, nestin, p75 and S-100p, as well as for most of the other markers tested. We conclude that a panel of S-100p, WT1, SOX10, p75 and nestin may constitute the optimal panel with the most sensitive and specific combination of immunostain available for the diagnosis of DM. [ABSTRACT FROM AUTHOR]

BACKGROUND In the current study, the authors sought to evaluate outcomes, specifically with respect to adjuvant radiotherapy (RT), for patients with desmoplastic melanoma. METHODS The records of 130 consecutive patients who presented between 1985 and 2009 with nonmetastatic desmoplastic melanoma and were treated curatively with either surgery alone (59 patients; 45%) or surgery and postoperative RT (71 patients; 55%) were retrospectively reviewed. Ages ranged from 21 years to 97 years (median age, 66 years). The location of the primary tumor was in the head and neck region in 62% of patients. Only 5 patients (4%) had lymph node involvement at the time of presentation. RESULTS The median follow-up was 6.6 years (range, 11 months-24 years). Overall survival rates at 5 years and 10 years were 69% and 53%, respectively. Disease-specific survival rates were 84% and 80%, respectively, at 5 years and 10 years. The actuarial rate of local recurrence was 17% at 5 years and beyond. Of the patients who underwent surgery without receiving postoperative RT, 14 (24%) experienced local recurrence. Of the 71 patients treated with surgery and postoperative RT, 5 (7%) experienced local recurrence. In a Cox multivariate regression model, improved local control was significantly associated with the receipt of postoperative RT ( P = .009). CONCLUSIONS Surgery followed by postoperative RT appears to provide superior local control compared with surgery alone for patients with desmoplastic melanoma. Cancer 2014;120:1361-1368. © 2013 American Cancer Society. [ABSTRACT FROM AUTHOR]

Melanocytes are pigment-producing cells that reside in the skin, eyes, ears, heart, and central nervous system meninges of mammals. Schwann cells are glial cells, which closely associate with peripheral nerves, myelinating, and sheathing them. Melanocytes and Schwann cells both arise from the neural crest during development, and some melanocytes arise directly from Schwann cell precursors lining developing spinal nerves. In this review, we explore the connections between melanocytes and Schwann cells in development and transformation. [ABSTRACT FROM AUTHOR]

doi: 10.1111/j.1741-2358.2011.00482.x Oral desmoplastic melanoma mimicking inflammatory hyperplasia Introduction: Desmoplastic melanoma (DM) arising in the oral cavity is a rare neoplasm that may be confused with a variety of non-melanocytic benign or malignant lesions. Objectives: To present a case of DM in the oral mucosa mimicking fibrous inflammatory hyperplasia, discusses the difficulties involved in the diagnosis and offers a literature review on the clinicopathologic and immunohistochemincal aspects of this neoplasm. Case report: A 62-year-old white male, smoker, was referred with a chief complaint of pain and swelling in the palate. The oral examination revealed multiple brown-to-black patches and a non-pigmented sessile nodule located on the mucosa of the hard palate. The clinical diagnosis of the pigmented lesions was either oral melanosis or melanoma. The nodular lesion was clinically diagnosed as fibrous inflammatory hyperplasia. Incisional biopsy was performed on the pigmented lesion and the microscopic sections revealed a melanotic macule. The nodular lesions histologically revealed an amelanotic desmoplastic melanoma. Conclusions: Reactive lesions close to a pigmented area should be investigated with great care. [ABSTRACT FROM AUTHOR]

We have observed 'fingerprint' immunopositivity in association with perineurioma and neurofibroma. A fingerprint consists of delicate, elongated areas of positive labeling that fall between collagen bundles, thereby creating a whorled configuration that is reminiscent of a human fingerprint. At present, the differential diagnosis between early desmoplastic melanoma and neurofibroma remains challenging in a subset of cases because of overlapping histopathological and immunohistochemical features. To assess whether fingerprint CD34 reactivity could be contributory in this context, we stained 50 desmoplastic melanomas and 50 neurofibromas with CD34. Fingerprint CD34 labeling was present in greater than 30% of the proliferation in 96% (n = 48) of neurofibromas and in only 4% (n = 2) of desmoplastic melanomas. Over two-thirds of the neurofibromas exhibited a CD34 fingerprint involving more than 60% of their surface area. In the two cases of desmoplastic melanoma that showed CD34 fingerprint positivity, the staining was patchy and involved less than 60% of the tumor. In partially staining neurofibromas, areas without a CD34 fingerprint tended to occur in central lobular areas.We conclude that CD34 fingerprint immunoreactivity is useful in distinguishing neurofibroma from early desmoplastic melanoma, especially if the fingerprint involves more than 60% of a tumor's cross-sectional area. [ABSTRACT FROM AUTHOR]

Background: Desmoplastic melanoma (DM) represents a relatively rare malignancy. The aim of this study was to describe the incidence and survival of DM in the United States. Methods: Incidence and survival data were obtained from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program, 1992-2007. Kaplan-Meier and Cox proportional hazards regression methods were used to calculate the survival rates and hazard ratios for DM-specific death. Results: We identified 1129 DM patients from SEER 13 registries, with 64% in men, 37% in women and most (96.8%) occurring in White populations. The incidence rates per 1,000,000 were 1.3 (female), 3.0 (male) and 2.0 (both). The annual percentage change for incidence was 4.6 (95% confidence interval: 2.9-6.5) from 1992 to 2007. The 5-year and 10-year DM-specific survival rates from SEER 17 registries were 84.8 and 79.2%. The 5-year DM-specific survival rates by stage ranged from 90.9% (local) to 51.5% (distant). Independent predictors of mortality from DM included age, anatomic site, thickness, ulceration, lymph node and surgery. Conclusions: The incidence of DM has been increasing steadily over the past 15 years. Older age, anatomic site of the head and neck, tumor thickness >2 mm, ulceration, lymph node involvement and non-receipt of surgery are associated with lower survival. [ABSTRACT FROM AUTHOR]

Murali R, Zannino D, Synnott M, McCarthy S W, Thompson J F & Scolyer R A (2011) Histopathology , 886-895 Primary cutaneous desmoplastic melanoma (DM) may be entirely desmoplastic ['pure' DM (pDM)] or exhibit a desmoplastic component admixed with a non-desmoplastic component ['combined' DM (cDM)]. Our aim was to describe the histological features of metastases of primary DM and to determine whether they were predictive of outcome. The effect of clinicopathological parameters on overall survival (OS) was analysed, and the correlation between histological features of the primary melanoma and metastases was studied in patients with metastatic DM. Twenty-six patients (18 males; eight females) developed 50 metastases in sentinel nodes (13; 26.0%), regional nodes (10; 20.0%), skin (14; 28.0%), and distant sites (13; 26.0%). The cellular composition of metastases correlated with that of the corresponding primary tumours. Time to development of first non-sentinel lymph node metastasis was shorter in cDM than in pDM (median 11.2 versus 24.9 months, P = 0.075). The only independent predictors of poorer OS were cDM type [hazard ratio 6.17, 95% confidence interval (CI) 1.61-23.81, P = 0.008] and male sex (hazard ratio 5.98, 95% CI 1.34-26.66, P = 0.019). The cellular composition of primary DM correlates with that of metastatic DM and with outcome. It is important to consider the possibility of primary or metastatic DM when examining tumours composed of spindle cells. [ABSTRACT FROM AUTHOR]

The histopathologic distinction of desmoplastic melanomas from sclerosing (desmoplastic) melanocytic nevi can be difficult, especially when evaluating a partial or superficial biopsy. In the study reported herein, we applied and explored the use of a novel ancillary method, a four-probe fluorescence in situ hybridization (FISH) assay targeting RREB1, MYB, Cep6 and CCND1, to this diagnostic problem. Fifteen sclerosing melanocytic nevi, including desmoplastic Spitz nevi, conventional nevi with prominent stromal sclerosis and sclerotic blue nevi, as well as 15 examples of desmoplastic melanoma, were examined. None of the sclerosing melanocytic nevi showed a level of chromosomal aberrations that met FISH criteria for melanoma. Seven of the 15 desmoplastic melanomas were 'positive' (had documented chromosomal aberrations) by FISH. Thus, a positive FISH test strongly supports the diagnosis of melanoma in this context. However, in this setting a negative FISH test is of limited diagnostic value. Our findings suggest that prior reports about the high sensitivity of the FISH test for melanoma diagnosis need to be adjusted according to melanoma subtype. Gerami P, Beilfuss B, Haghighat Z, Fang Y, Jhanwar S, Busam KJ. Fluorescence in situ hybridization as an ancillary method for the distinction of desmoplastic melanomas from sclerosing melanocytic nevi. [ABSTRACT FROM AUTHOR]

The article focuses on a study which identified the prognostic factors in cutaneous desmoplastic melanoma (DM). The study included patients diagnosed with clinically localized primary cutaneous melanoma (PCM) containing desmoplastic component. The clinical and pathologic features of the patients' primary tumors were examined and correlated with DM type, sentinel lymph node (SLN) status and outcome. The study found that SLN-positive rate was lower in patients with DM compared to those with conventional melanoma.

McKee P H (2010) Histopathology 56, 100–111 Clues to the diagnosis of atypical melanocytic lesions This review, based on a lecture given at the 2009 Update in Dermatopathology meeting held at the Institute of Dermatology (London, UK), discusses the problem of misdiagnosing atypical benign melanocytic lesions as melanoma and the alternative problem of interpreting naevoid melanoma as a banal naevus. Consequences are considered. Brief consideration of a range of other melanoma variants that may be a source of diagnostic difficulty is also included. [ABSTRACT FROM AUTHOR]

Background: Desmoplastic melanoma (DM) is a rare subtype of cutaneous malignant melanoma reported to have a high local recurrence rate with surgical excision alone. The incidence of regional and distant metastasis is considered to be lower than traditional cutaneous melanoma, warranting more aggressive treatment of local disease. We conducted a retrospective analysis of patients with DM treated through the Princess Alexandra Hospital Melanoma Clinic to address the role of radiotherapy in the local control of this tumour. Methods: A review of a clinical database identified 24 patients between January 1997 and March 2006 with histopathologically confirmed DM who had received surgical excision as initial treatment followed by postoperative radiotherapy. All histopathology reports and radiotherapy treatment plans were reviewed. The primary outcome measure was 3-year in-field relapse-free survival. Results: There were 24 patients with 22 having a DM in the head and neck region. The median tumour thickness was 5.2 mm. The histopathological margin was less than 10 mm in 17 (71%) of patients. The 3-year in-field relapse-free survival was 91% (95% confidence interval 68.1–97.6%), the 3-year relapse-free survival was 86% (95% confidence interval 63.2–95.4%) with a 3-year overall survival of 83% (95% confidence interval 54.9–94.3%). Conclusion: In a selected series of patients with DM with a high risk of local recurrence, adjuvant radiotherapy may have been effective in reducing the rate of local recurrence after surgical resection. A randomized trial is currently being developed to confirm this possible benefit. [ABSTRACT FROM AUTHOR]

The histological distinction of desmoplastic melanoma from cutaneous scar tissue, particularly in the context of re-excision specimens or possible recurrence, may be very difficult. Immunostaining for S100 protein is often used to discriminate although there are little data on S100 expression in scar tissue. The aim of this study was to assess whether S100-positive cells are present in dermal scars and, if so, their extent, distribution and nature. Twenty-two re-excision specimens of previously biopsied nonmelanocytic skin lesions were reviewed. Formalin-fixed paraffin-embedded sections containing dermal scars were stained by a standard ABC immunoperoxidase technique for S100 protein, CD1a and neurofilaments. The distribution and morphology of positive cells within the dermal scar tissue were documented. Cells expressing S100 protein were identified within the scars of 21 of the 22 cases. The number of S100-positive cells varied between cases but in four specimens was substantial. They displayed a variety of morphological appearances but the majority were spindle-shaped. A few showed mild cytological atypia. It is suggested that the majority represent Schwann cells with a minority of Langerhans cells and cells of uncertain lineage. S100-positive cells, including spindle cells showing mild atypia, are found in cutaneous scars. S100 staining of re-excision specimens or putative recurrences of desmoplastic melanoma should be interpreted with caution. [ABSTRACT FROM AUTHOR]

Aims:The staining pattern of the recently described antibody melan-A was compared with those of S100 protein and HMB-45 in a variety of melanocytic lesions to assess the specificity and sensitivity of these antibodies. Methods and results:Immunohistochemical staining of paraffin sections of a range of melanocytic lesions was carried out following a high temperature antigen retrieval technique. The pattern and intensity of staining was semiquantitatively scored. S100 remains the most sensitive marker of melanocytic differentiation being diffusely positive in all benign and all primary and secondary malignant lesions including naevoid melanomas, and in most desmoplastic/spindle cell melanomas. Of the two more specific melanocytic markers melan-A stains the majority of benign and malignant lesions diffusely but with occasional patchy positivity only in some secondary melanoma deposits and with little staining of desmoplastic/spindle cell melanomas. HMB-45 is the least sensitive of the three showing little positivity of benign mature naevus cells, only variable patchy positivity of primary and secondary melanoma cells and limited positivity in naevoid, desmoplastic and metastatic melanomas. Conclusions:Melan-A is a useful addition to antibody panels as it is apparently specific for melanocytic lesions and is more sensitive than HMB-45; however, it has less value than S100 in the detection of spindle cell and desmoplastic melanomas. [ABSTRACT FROM AUTHOR]

The article discusses cellular neurothekeomas which are distinctive benign cutaneous tumors of uncertain histogenesis. It notes two cases of this tumor wherein the prominent feature was the presence of perineural invasion that refers to cancer spreading to the space surrounding a nerve. It is also known as a pathologic process in which tumor cells will invade into nervous structures and spread along nerve sheat.