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Mammary myofibroblastoma (MFB) is a rare benign spindle cell neoplasm of the breast that can exhibit both epithelial and mesenchymal elements. The histomorphologic features of MFB mimic other potentially more aggressive neoplasms of the breast that may require more involved clinical management beyond a conservative local excision. We present the case of a 71-year-old male with a mammary MFB who underwent core needle biopsy (CNB) of a well-defined, bland spindle cell neoplasm with a subsequent local excision. The case highlights triage of MFB among a broad diagnostic differential at biopsy, particularly given its multipotent differentiation potential and highly variable presentation from the standpoint of both radiology and histopathology. We also discuss the role of RB1 deficiency in distinguishing MFB from other tumor types and non-neoplastic/reactive proliferations.

Schwannomas are benign tumors derived from the sheath of Schwann cells. Though it is common to see schwannomas in the head and neck region, auricular schwannomas are rare and only few cases have been reported. There are no distinguishing clinical findings or images; therefore, the histopathological diagnosis is mandatory. We describe a case of auricular schwannoma with clinical pictures and discuss the differential diagnoses according to histopathologic findings. [ABSTRACT FROM AUTHOR]

Background: While cutaneous melanoma is common in up to 2.6% of Caucasian population, it is far less common in the African American population, up to 0.1%. Additionally, anal melanoma in particular comprises less than 1% of all melanomas and roughly 4% of anal cancers, while Spindle-cell variants are even less common, suggesting an extremely low incidence in the African American population. Definitive diagnosis can be challenging due to lack of definitive mass or pigmentation at presentation. There is a lack of good long-term studies and treatment guidelines for this malignancy with significant variation in treatment approaches and patient outcomes. Case description: Here we present a case of an 63-year old African American gentleman with no significant past medical history and unremarkable colonoscopy 3 years prior, who presented with a mass in the anal canal that was found during a scheduled screening colonoscopy. The patient was completely asymptomatic at presentation. PET/CT scan showed hypermetabolic activity in the anal canal region. Patient underwent surgical excision with pathology revealing a 2.7 cm spindle cell type of malignant melanoma and promptly treated with adjuvant immunotherapy, resulting in extended progression-free survival before recurrence in the liver. Conclusion: The early diagnosis of spindle cell melanoma can prompt more aggressive surgical and systemic management options resulting in extended survival, however, late recurrences are common and often refractory to standard therapeutic options.

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm known to occur at various soft tissue and visceral locations. Kidney is one of the rare locations for these tumors with around 64 cases being available in the literature. Most of the renal SFTs are tan-white, solid, firm, unencapsulated, and lobulated masses. A predominantly cystic renal SFT has never been reported in the literature. Herein we describe a case of multicystic renal SFT in a 44-year-old male with the characteristic CD34 + /STAT6 + immunophenotype. A careful gross and microscopic examination is warranted while dealing with cystic spindle cell neoplasms of the kidney and SFT should always be considered in the differential diagnosis. STAT6 immunohistochemistry is quite specific for the diagnosis. Moreso, a detailed immunopanel is necessary to exclude other spindle cell neoplasms of the kidney because of significant therapeutic and prognostic implications. [ABSTRACT FROM AUTHOR]

Introduction: NTRK-rearranged spindled cell tumors have been increasingly recognized with the widespread use of molecular studies. We describe a pediatric spindle cell neoplasm with MTAP-RAF1 gene fusion that fits into this group. Case report: An 8-year-old girl presented with mandibular mass. Histopathologically, it was a moderate to increased cellular spindle cell tumor with mild-to-moderate nuclear pleomorphism, focal perivascular keloid-like collagen, that was positive for S-100 and CD34. MTAP-RAF1 fusion was detected by next generation sequencing, confirming a low-grade sarcoma with MTAP-RAF1 fusion that is presently included in the category of NTRK-rearranged spindled cell tumors. Discussion: MTAP-RAF1 fusion, in the spectrum of spindle cell neoplasms with kinase gene rearrangements, can occur in the pediatric age group. [ABSTRACT FROM AUTHOR]

The spindle cell neoplasms include sinonasal tract angiofibroma (STA), glomangiopericytoma (GPC), and biphenotypic sinonasal sarcoma (BSNS). These entities share some clinical, histomorphologic, immunohistochemical, and even molecular characteristics. Nevertheless, there are features that are unique to each tumor type. STA shows heavily collagenized and vascular stroma, with apparent relationship to underlying hormonal changes. GPC consistently exhibits monomorphic, ovoid cytologic appearance with the constant feature of Beta-catenin nuclear accumulation by IHC. Lastly, BSNS is a deceptively bland and neural-like neoplasm featuring consistent co-expression of S100 and smooth muscle markers with specific genetic rearrangements serving to uniquely characterize this entity., Competing Interests: Disclosures The authors have nothing to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Myofibroma is a rare benign spindle cell neoplasm which occurs predominantly in infants and young children. It can occur as a solitary mass or as a multicentric lesion, consisting of myofibroblasts. In oral cavity, the sites most commonly involved are the mandible, tongue, lips and buccal mucosa however, it rarely involves the maxilla. It has aggressive clinical presentation mimicking malignancies. We report a case of a male child seven years of age presented with intraoral swelling on the left palatal aspect of the maxilla that extended from deciduous upper left second molar to the distal of upper permanent left first molar causing the mobility of these teeth. Radiologically, the lesion was osteolytic causing marked resorption of alveolar bone and displacement of permanent maxillary left second molar. A differential diagnosis of peripheral giant cell granuloma, central giant cell granuloma, fibroma, aggressive fibromatosis, nodular fasciitis, peripheral ossifying fibroma and spindle cell neoplasm was made. After the excluding malignant and vascular involvement, the surgical excision of the lesion was planned and was carried out under general anesthesia. Histologically, benign proliferation of spindle cells was seen giving the diagnosis of benign spindle cell neoplasm. Reports also showed positive immunoreactivity with vimentin and aSMA while non-responsive to desmin, validates the diagnosis of myofibroma. [ABSTRACT FROM AUTHOR]

Spontaneous intestinal perforations in the neonatal population are mostly associated with low birth weight, prematurity, and necrotizing enterocolitis. Spontaneous intestinal perforation in the absence of these risk factors is extremely rare and should raise clinical concern for an underlying bowel pathology. Here we present a unique case of a normal-weight, full-term girl with spontaneous intestinal perforation due to a spindle cell neoplasm with a novel BRAF mutation and infantile fibrosarcoma-like morphology. Though rare, malignancy should be considered in the differential diagnosis for bowel perforation in an otherwise healthy, term infant as complete surgical excision can be curative.

Gastrointestinal (GI) intestinal stromal tumors account for 60% of mesenchymal GI tract tumors commonly located in the stomach and small intestine, predominantly solid tumors that rarely undergo cystic degeneration. A 65-year-old patient with increasing upper abdominal swelling and a computed tomography scan abdomen showed a large unilocular 17 × 16 × 15 cm lesion. A colossal cystic swelling in the lesser omentum, anterior to the stomach, was found upon exploration. Histopathological examination showed a spindle cell tumor turned out to be CD117 positive and S100 negative on immunostains. The tumor was moderate risk gastric gastrointestinal intestinal stromal tumor (GIST) based on the site; Stomach, Size >10 cm; Mitosis <5/5 mm2 according to risk assessment of GIST, 2006. GISTs are predominantly solid tumors and rarely undergo cystic transformation. The primary differential diagnoses of spindle cell neoplasm are GISTs, Leiomyoma, Leiomyosarcoma and Schwannoma. These spindle cell neoplasms are differentiated by applying a panel of Immunohistochemical stains, CD117, SMA and S100. [ABSTRACT FROM AUTHOR]

Synovial sarcoma is a rare mesenchymal malignant neoplasm that presents a specific t(X;18) translocation forming SS18(SYT)-SSX chimera gene. It is most commonly seen in soft tissues of the extremities. The digestive tract is an exceptional site of involvement. We report a case of primary gastric synovial sarcoma in a 48-year-old female. Differential diagnosis of synovial sarcoma from other spindle cell, mesenchymal and cytokeratin-positive tumors is critical for the treatment and prognosis. Immunohistochemistry studies and molecular analysis are required to settle a proper diagnosis.

Aggressive fibromatosis is a rare, benign proliferative disease with unknown aetiology and high recurrence rate. To date, there are only eight reported cases affecting the larynx. Four were managed with total laryngectomy, whilst spontaneous regression happened in one case. Spindle cell carcinoma is a rare but highly aggressive biphasic tumour which often arises in the head and neck. Diagnosed with laryngeal fibromatosis more than 10 years ago, our patient had undergone six trans-oral laser debulking procedures. On this occasion, he presented with a two-week history of severe worsening dyspnoea and hoarseness of voice, requiring urgent debulking. Final pathology results revealed spindle cell carcinoma of the larynx. In this report, we describe the case of laryngeal fibromatosis which progressed to spindle cell carcinoma. To our knowledge, no such case has been described previously. This case highlights an important complication of laryngeal fibromatosis and emphasises the importance of regular follow-ups., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Dhunnoo et al.)

The laryngeal tumor type, location and disease extent are essential determinants in deciding the type of surgery and the potential voice and swallowing outcomes. The surgical options available are conservative laryngeal surgeries like transoral laser microsurgery (TLM) or open conservative laryngeal surgery and Total laryngectomy. We report an unusual case of low-grade Myofibroblastic sarcoma of vocal cord which was managed by TLM. [ABSTRACT FROM AUTHOR]

Solitary fibrous tumor (SFT) is a relatively uncommon spindle cell mesenchymal neoplasm that is most often based on the pleura but may rarely arise in extrapleural locations, including the skin. Herein, we describe three cases of cutaneous SFTs. SFT is characterized by epithelioid and spindle cells arranged in random patterns with focal prominent stromal collagen and pericytomatous vessels. Immunohistochemical evaluation is required for definitive distinction of SFT from other benign and malignant cutaneous spindle cell neoplasms. Although aggressive biologic behavior is uncommon, accurate diagnosis of it is required for prognostication and counseling. CD34, bcl‐2, and CD99 stains are positive in SFT, but not specific. STAT6 is the most sensitive and specific immunohistochemical marker to confirm diagnosis of SFT. [ABSTRACT FROM AUTHOR]

The spectrum of tumors with NTRK1/2/3 rearrangements has expanded with widespread use of next generation sequencing (NGS) technology. For many years it was known that a majority of infantile fibrosarcomas (IFS), and their counterpart in the kidney, cellular congenital mesoblastic nephroma, contain the recurrent ETV6-NTRK3 fusion. Sequencing RNA transcripts from IFS and their morphologically similar counterparts in older children and adults has shown rearrangements with other 5′ partners combined with NTRK1, NTRK2 , and NTRK3 can also occur. For those tumors occurring outside of the infant age group, this has resulted in a proposed new diagnostic entity of " NTRK -rearranged spindle cell neoplasm." The clinical behavior of NTRK rearranged soft tissue tumors varies, though most show localized disease with rare metastases. The pathology of NTRK rearranged tumors exists on a spectrum, with overlapping features of classic infantile fibrosarcoma, lipofibromatosis, and malignant peripheral nerve sheath tumor. In this tumor spectrum, clinical and pathologic predictive factors are largely still to be determined, with no clear association between histologic grade and severity of disease. Of critical importance is detection of the NTRK rearrangement in order to guide treatment in patients with unresectable and metastatic disease. While resection is the definitive treatment, these tumors do show response to targeted TRK kinase inhibitors. Multiple detection methods are available, including immunohistochemistry, FISH, and next generation sequencing, which each have their merits and potential pitfalls. We aim to review the clinical characteristics and histomorphology of mesenchymal tumors with NTRK rearrangements as well as discuss molecular detection methods and diagnostic algorithms specific for soft tissue tumors. [ABSTRACT FROM AUTHOR]

Cutaneous leiomyomas, benign tumors from smooth muscle fibers, constitute about 5 % of all leiomyomas. They exhibit diverse inheritance patterns and can be linked to systemic malignancies. Gastrointestinal stromal tumors (GISTs), arising from the interstitial cells of Cajal, are the most common mesenchymal tumors in the gastrointestinal tract. Despite their prevalence, simultaneous occurrences of cutaneous leiomyomas and GISTs are rare, necessitating exploration of their potential relationship. A 25-year-old male with no significant medical history presented with multiple painful erythematous nodules on his chest, upper back, and arms. Histopathological analysis diagnosed these as multiple cutaneous piloleiomyomatosis. Despite recommendations for surgical intervention, the patient chose medical management and experienced significant pain relief with nifedipine. Later, the development of abdominal symptoms led to the discovery of multiple gastric lesions, diagnosed as benign spindle cell neoplasms, necessitating partial gastrectomy. The differential diagnosis of cutaneous leiomyomas includes various soft tissue tumors, requiring histopathological confirmation. Genetic mutations affecting proteins critical to cellular energy production and tumor suppression underlie these conditions. Treatment options include pharmacological management and surgical excision. The discovery of GISTs in this patient aligns with rare literature reports, emphasizing the need for vigilant evaluation of systemic malignancies in patients with leiomyomatosis. This case highlights the potential of cutaneous leiomyomas to indicate deeper malignancies like GISTs, stressing the importance of interdisciplinary collaboration in diagnosis and treatment. It underscores the interconnectedness of benign dermatological conditions and internal malignancies, advocating for comprehensive evaluation in patients with leiomyomatosis. This case report meticulously follows the SCARE 2023 guidelines: updating consensus Surgical Case Report guidelines (Sohrabi et al., 2023 [ 1 ]). These guidelines ensure high-quality reporting in surgical case reports. The report details the evaluation, diagnosis, and a comprehensive review of the literature pertaining to a patient with multiple leiomyoma cutis associated with gastrointestinal stromal tumors. By employing a multidisciplinary approach, this report achieves a thorough and standardized presentation of the case, serving as an additional tool for raising awareness regarding such rare conditions. • A unique case of a young man with cutaneous leiomyomatosis and concurrent gastrointestinal stromal tumors. • The case illuminates genetic aspects of leiomyomatosis, emphasizing the role of fumarate hydratase mutations in disease manifestation. • Emphasis on management choices for leiomyoma cutis and Gastrointestinal Stromal Tumors. • Demonstrates the importance of a multidisciplinary approach in diagnosing and managing patients with leiomyomatosis and potential associated malignancies. [ABSTRACT FROM AUTHOR]

A solitary infantile myofibroma tumor arises as a hard, painless cutaneous or subcutaneous nodule and is defined as an uncommon soft tissue neoplasm that is usually seen in childhood. A nine-month-old female infant presented with a solid mass that appeared one month ago. The mass gradually increased in size within the right posterior triangle of the neck, without any local or systemic accompanying symptoms. Laboratory tests were normal. Ultrasonography revealed a homogeneous tissue mass measuring 1.5 × 3 cm, with blood flow within it. Multislice CT scan accurately localized the isolated tumor. The mass was surgically excised and found within the sternocleidomastoid muscle, without any adhesions to adjacent tissues. Histological examination of the tumor and immunohistochemical tests confirmed infantile myofibroma. IM is one of the most common soft tissue tumors in children and mainly consists of myofibroblasts. 90 % of IM cases are diagnosed before the age of two years. Possible therapeutic measures for this tumor include conservative management, surgical resection, chemotherapy, radiation therapy, and steroid injections into the tumor. Surgical removal of the tumor is often performed, and if it is single and completely removed, the prognosis is good with a recurrence rate of less than 10 %. Infantile myofibroma is considered a benign tumor, but it may be fatal in some cases. Each case is treated individually according to the number (single or multicentric), size, location, symptoms, and visceral involvement. Surgical resection remains the therapeutic procedure of choice in most cases. • Infantile myofibroma (IM) is a rare benign tumor that typically occurs before the age of two years. • An isolated myofibroma accounts for 70% of IM cases, and in one-third of cases, it is located in the head, neck, or trunk. • Complete surgical resection is the preferred treatment. • A biphasic growth pattern is the descriptive histological feature of IM. [ABSTRACT FROM AUTHOR]

We report a case of multiple bilateral pulmonary myofibromas in an asymptomatic 76-year-old man, who was referred to our institution for investiagtion of incidentally discovered pulmonary nodules, orginially suspected to represent pulmonary metastases. Myofibromas are unusual benign neoplasms, infrequent in adults, and rarely affecting the lungs. Pulmonary myofibromas can mimic lung metastases and their diagnosis requires histopathological assessment.

Biphenotypic sinonasal sarcoma (BSNS) is a rare recently described distinct spindle cell sarcoma which arises exclusively in the sinonasal region and is characterized by concomitant neural and myogenic differentiation. Before this neoplasm was characterized, most were classified as other entities including adult fibrosarcoma, monophasic synovial sarcoma and malignant peripheral nerve sheath tumor. By immunohistochemistry, these tumors characteristically express S100 and smooth muscle actin (SMA) and/or muscle specific actin (MSA). Most cases harbor rearrangements of PAX3 (paired box gene 3), and the most frequent translocation partner is MAML3 (mastermind like transcriptional coactivator 3). Herein, we described three cases of BSNS involving the nasal cavity with or without paranasal sinus involvement. We also did a literature review of the clinical features, histologic and immunophenotypic findings, cytogenetics, pathogenesis and behavior of this rare entity.

Leiomyoma is a benign smooth muscle tumor that frequently occurs in the uterine myometrium of the uterus and gastrointestinal tract rarely but seldom encountered in the oral cavity, particularly in children. Its occurrence in the oral cavity is considered rare probably because of the scarcity of smooth muscle tissue in the oral cavity. The frequently affected anatomical areas intraorally are lips, palate and tongue. The purpose of this case report is to put forth a rare case of oral leiomyoma in a 10-year-old girl child involving the retromolar region. [ABSTRACT FROM AUTHOR]

GI stromal tumors (GISTs) are the most common mesenchymal neoplasms in the GI tract. GISTs are malignancies that typically originate in the digestive system, most often in the stomach and small intestine. Histopathological classification identifies three types of GISTs: spindle cell, epithelioid, and mixed. We present a case of a huge intra-abdominal retroperitoneal mass in a 23-year-old female with no notable medical or surgical history. She experienced dysphagia and early satiety for one year but did not seek medical attention until presenting at our clinic. Her abdomen was distended, soft, and firm, with a huge non-tender mass. Abdominal CT revealed a substantial left retroperitoneal soft tissue lesion measuring 17 × 12 × 21 cm, causing a significant mass effect. An exploratory laparotomy via a thoracoabdominal approach was performed. A definitive diagnosis required surgical intervention or tissue biopsy. This case highlights the rarity of spindle cell neoplasms and underscores the importance of maintaining a high index of suspicion for such tumors in young adults., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Elgeyoushy et al.)

Myofibroma is a benign, soft tissue neoplasm that predominantly affects infants and young children. Most occur in the skin or subcutaneous tissues, with a predilection for the head and neck regions. We describe the magnetic resonance (MR) imaging and histophathologic findings of a rare case of intramuscular myofibroma of the right deltoid in a healthy 30-year-old male. MR imaging revealed a well-circumscribed intramuscular mass, with isointense signal on T1-weighted images, hyperintense signal on T2-weighed images, and a "target-sign" with peripheral rim enhancement after gadolinium administration. The lesion was surgically excised with no complications, and the histopathologic analysis revealed the typical morphologic and histochemical markers of a myofibroma. We conclude that, although rare, myofibroma can be considered in the differential diagnosis of adults with lesions the above signal characteristics. • Benign neoplasms of soft tissues with myofibroblastic differentiation • Historically a pediatric illness, peak before age 2; adult cases solitary and benign • Mostly sporadic; some congenital cases linked to PDGFR-beta and NOTCH3 genes. • Intramuscular myofibromas rare; common locations skin/subcutaneous and head & neck • Enhancing iso- to slightly hyperintense on T1 and hyperintense on T2; "target sign" [ABSTRACT FROM AUTHOR]

Synovial sarcoma is a rare mesenchymal malignant neoplasm that presents a specific t(X;18) translocation forming SS18(SYT)-SSX chimera gene. It is most commonly seen in soft tissues of the extremities. The digestive tract is an exceptional site of involvement. We report a case of primary gastric synovial sarcoma in a 48-year-old female. Differential diagnosis of synovial sarcoma from other spindle cell, mesenchymal and cytokeratin-positive tumors is critical for the treatment and prognosis. Immunohistochemistry studies and molecular analysis are required to settle a proper diagnosis. [ABSTRACT FROM AUTHOR]

Retroperitoneal spindle cell neoplasms are diagnostically challenging. Malignant peripheral nerve sheath tumours (MPNSTs) can sometimes present as sporadic primary retroperitoneal tumours. MPNSTs are usually high-grade and highly aggressive tumours and are associated with a poor prognosis. Low-grade MPNSTs are very rarely described. This current case report describes a case of sporadic primary low-grade MPNST presenting as retroperitoneal spindle cell neoplasm. The diagnosis, imaging and immunohistopathological findings, as well as its successful surgical management, are presented., Competing Interests: Declaration of conflicting interestThe authors declare that there are no conflicts of interest.

“Spindle cell neoplasm” is a descriptive term and the differential diagnosis includes tumors that vary in morphology and immunohistochemistry. We present a ten-year-old female patient with a recurrent spindle cell neoplasm of the nasal sidewall that lacked the clinical and histological characteristics of well-known diagnostic entities. The patient underwent resection and paramedian forehead flap reconstruction. Decisions regarding reconstructive technique, timing, and surveillance were challenging given her age, the anatomic location, and infiltrative nature of the lesion. In this report, we review the uncommon spindle cell neoplasms of the head and neck and present a treatment plan to assist other clinicians.

An emerging group of spindle cell neoplasms harboring fusions involving NTRK or non-NTRK kinase genes often share characteristic S100 and/or CD34 expression; however, the diagnostic utility of immunohistochemical stains is not well established in this family owing to their lack of specificity. Recently, CD30 expression in spindle cell neoplasms with kinase gene fusions, such as NTRK, BRAF, RAF1, and RET, has been increasingly identified. We herein report a 10-year-old girl with high-grade spindle cell sarcoma of the neck. Prior to histopathological evaluation, flow cytometry (FCM) analysis and touch smear cytology of the tumor tissue revealed CD34+ and dimCD30+ spindle cell populations. Histopathologically, the case was characterized by monomorphic spindle-shaped cytomorphology with CD30, S100, and CD34 positivity and harbored close similarities with spindle cell neoplasms with NTRK or non-NTRK gene fusions. Subsequently, a comprehensive next-generation sequencing sarcoma panel identified a rare PLEKHH2::ALK fusion, and a diagnosis of ALK-rearranged spindle cell neoplasm was made. The patient showed significant tumor response to single-agent treatment with alectinib, an ALK-tyrosine kinase inhibitor. This case supports that CD30 is expressed in an ALK-rearranged mesenchymal neoplasm. The benefit of the early detection of CD30 expression by FCM for a prompt diagnosis and treatment is highlighted in the context of an aggressive clinical course. This case represents a learning experience regarding the need to the check the status of CD30 expression in these tumors and suggests the potential clinical benefits of CD30-targeted therapy., (© 2024 Wiley Periodicals LLC.)

Follicular dendritic cells (FDC) are nonlymphoid, nonphagocytic accessory cells in the immune system. They have major roles in antigen presentation and regulation of germinal center reaction. FDC sarcoma is a rare and under-recognized malignancy. Most of the cases are reported in the lymph nodes. The typical morphology is syncytial aggregates of oval/spindly cells with vesicular bland nuclei and small nucleoli. Focal whorling and storiform pattern, multinucleate giant cells, and the presence of small lymphocytes in the background give additional clues for the diagnosis. As spindle cell tumors are rare in the lymph nodes, FDC sarcoma comes under the differential diagnosis of spindle cell neoplasms of the node and an accurate diagnosis is often rendered. However, when the neoplasm occurs in extranodal sites, the diagnosis is often missed because the FDC markers are not routinely used in the immunopanel for undifferentiated neoplasms. Because of its rarity, the extranodal FDC sarcomas pose a great diagnostic challenge and often misdiagnosed initially. Herein, we report a case of FDC sarcoma of the tonsil in a 36-year-old female patient. Biopsy of the lesion showed oval to spindly cells in syncytial sheets and focally in whorled pattern. The individual cells were having plump vesicular nuclei and small nucleoli. Occasional multinucleate cells and sprinkling of lymphocytes within the tumor were also noted. The tumor cells were positive for CD23 and CD35. A diagnosis of FDC sarcoma was given. Greater awareness of the morphologic spectrum of FDC sarcoma and appropriate immunostains for FDC differentiation will help in recognition of this rare neoplasm. [ABSTRACT FROM AUTHOR]

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm that originates from dendritic cells of lymphoid follicles and shows low to intermediate malignant potential. It most commonly arises from lymph nodes, but may originate from a variety of extranodal sites. FDCS of appendix is exceptionally rare, and only a single case has been reported. Herein, we describe the clincopathological features of a case of FDCS originating from appendix with emphasis on being able to recognize this rare neoplasm in the context of the differential diagnosis of more common intraabdominal spindle cell tumors. [ABSTRACT FROM AUTHOR]

A 10-year-old female koi subspecies ( Cyprinus carpio ) was presented with bilateral, asymmetric, sessile masses of the periventiductal tissue. The owner had first observed the masses for approximately 1 year before seeking a veterinary evaluation of the fish. Over the past year, the sessile masses continued to grow and develop in size. An incisional biopsy was performed under general anesthesia to further assess the abnormal tissue structures. Based on the histologic evaluation of the submitted biopsy sample, the growth was determined to be a benign spindle cell neoplasm. The koi also was diagnosed with a concurrent genital tract infection based on cytological examination of the reproductive tract fluid. Following transport to the Veterinary Medical Teaching Hospital for further evaluation, a coelomic ultrasound revealed local infiltration of the tissue to the surrounding tissue. To decrease the risks of recurrence following surgical debulking, chemotherapy was recommended to treat the tissue adjacent to the tumor. Cultures obtained from the genital pore resulted in the isolation of Aeromonas spp. susceptible to ceftiofur, which was elected as a preemptive antibiotic. Surgical debulking of the mass was performed, and bleomycin was administered intralesionally and at the periphery of the surgical site. The koi recovered successfully from anesthesia and was discharged later the same day and prescribed an analgesic regimen of meloxicam. After further histological examination of the submitted tissue samples from the periventiductal growths, the tumor was identified as a leiomyoma. No recurrence of the mass was detected 6 months following the surgical procedure and chemotherapy. [ABSTRACT FROM AUTHOR]

ABSTRACT: Vaginal spindle cell neoplasm is a very rare tumour .It consists of mesmchymal & epithelial components. The presence of glandular structures and pattern of immunostaining, help in differentiating tomour from other vaginal neoplasm. It usually presents with slowly enlarging nodule in vagina. Reoccurrence is very rare

NTRK-rearranged spindle cell neoplasms (NTRK-RSCNs) represent an emerging group of rare tumours defined using molecular means. To the best of our knowledge, there have been no large series of reports about this tumour in the Chinese population in English full-text articles. Herein, we present 13 NTRK-RSCNs with peculiar characteristics. Ten of the 13 (77%) patients were children without sex differences. The tumour locations included six trunks, four extremities, two recta, and one small bowel. The histological morphology included four lipofibromatosis-like neural tumour (LPF-NT)-like, eight malignant peripheral nerve sheath tumours (MPNST)/fibrosarcoma-like, and one extremely rare myxofibrosarcoma-like pattern. Immunohistochemically, all cases were CD34, pan-TRK and TRK-A positive, SOX-10 negative, and H3K27me3 intact. S-100 protein expression was identified in 11 of 13 (85%) cases. Genetically, NTRK1 rearrangements were considered positive (7/13, 54%) or suspicious for positivity (6/13, 46%) by fluorescence in situ hybridisation. Next-generation sequencing and Sanger sequencing confirmed NTRK1 fusions with a variety of partner genes, including five LMNA, three TPM3, one SQSTM1, three novel CPSF6, IGR (downstream PMVK), and GAS2L1 genes. Interestingly, the last tumour concurrently harboured a second EWSR1-PBX1 fusion, which has never been reported. Four patients developed local recurrence and two of them suffered metastasis. In our study, NTRK-RSCNs had peculiar fusions that displayed unusual or complicated clinicopathological features. Histological clues and IHC helped streamline a small subset of potential candidates. Although FISH is a powerful technology for identifying NTRK rearrangements, RNA-/DNA-based NGS is recommended for highly suspected cases in which FISH signal patterns are not discernible as classic positive patterns, particularly if targeted therapy is considered., (Copyright © 2022 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.)

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Myofibroma and myofibromatosis is a well-recognized spindle cell neoplasm that occurs predominantly in infants and young children. They have been described under different names since 1951. These lesions are a benign fibroblast and myofibroblast proliferation containing a biphasic presentation of spindle shaped cells surrounding a central zone of less differentiated cells focally arranged in a hemangiopericytoma like pattern. Classically these lesions are described in children younger than two, with 2/3rd present at birth and rarely in adults. Controversy exists as to an autosomal dominant or recessive inheritance or to a sporadic occurrence. Presented here is a unique case of myofibroma involving the mandible in a 11 year-old male patient. Clinically it mimicked more like a beningn tumor and not exhibiting any of its classical signs. The diagnosis could be established only after complete excision of the lesion and histopathological examination. There was no recurrence after a follow up period of 4 months. [ABSTRACT FROM AUTHOR]

BACKGROUND Fine-needle aspiration biopsy of spindled mesenchymal lesions, including schwannomas, are challenging because of overlapping cytomorphological features. The objective of the current study was to identify key diagnostic cytological criteria for the diagnosis of schwannoma and to distinguish it from its common mimics. METHODS A total of 58 schwannomas were evaluated and compared with 98 benign and low-grade spindle cell lesions, including 17 gastrointestinal stromal tumors and 20 fibromatosis cases. Biopsy confirmation was available for all cases. The authors semiquantitatively evaluated cellularity, quality of stroma (fibrous and fibrillar), the presence of single cells with bipolar cytoplasmic processes, and marked nuclear pleomorphism (in the absence of other features of malignancy). Nuclear features evaluated included fishhook-type nuclei, intranuclear inclusions, chromatin pattern, and nucleoli. RESULTS Schwannomas demonstrated cohesive tissue fragments with fibrillary and occasionally fibrous stroma. The presence of intranuclear inclusions and marked nuclear pleomorphism and the absence of single cells with bipolar cytoplasmic processes emerged as statistically significant differences between the schwannoma and the nonschwannoma groups. When 5 criteria were present (high numbers of clusters, few to no single cells, fibrillary stroma, nuclei with pointed tips, and anisonucleosis) the sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of schwannoma were 22%, 97%, 81%, and 68%, respectively. CONCLUSIONS Cohesive tissue fragments with fibrillary/fibrous stroma, intranuclear inclusions, marked nuclear pleomorphism, and the absence of spindled cells with bipolar cytoplasmic processes are strongly suggestive of schwannoma and assist in excluding potential mimics. Cancer (Cancer Cytopathol) 2015. © 2015 American Cancer Society. Cancer (Cancer Cytopathol) 2015;123:171-179. © 2014 American Cancer Society. [ABSTRACT FROM AUTHOR]

Prostatic stromal sarcoma is a rare neoplasm, and we present a case of high-grade stromal sarcoma in a 50-year-old male with initial clinical presentation of difficulty in micturition. After initial evaluation by core needle biopsy, diagnosis was established on radical cystoprostatectomy specimen based on morphology and immunohistochemistry. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 17-year-old female with enlarging lesion on the posterior neck and mentions the medallion-like dermal dendrocyte hamartoma. Topics discussed include plaque-like CD34-positive dermal fibroma, dermal proliferation of spindled cells occupying the reticular dermis and proliferation of dermal dendritic cells.