Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract are genetically different from nodular fasciitis and lack USP6, ROS1 and ETV6 gene rearrangements

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145266/1/his13526_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145266/2/his13526.pd

Autoamputating dermatofibrosarcoma protruberans

This case is a 31 year old healthy female who presented with a skin lesion of several years, slowly increasing in size that had spontaneously fallen off her back. Previously, an outside institution determined this was a keloid, but no biopsy was performed. On examination, there was a 2 • 2 cm circular wound with mild bleeding on her back with adjacent nodularity, but no surrounding erythema. The detached lesion was a 2 • 2 • 0.5 cm flesh colored cauliflower form mass with a clean base. The clinical impression was dermatofibroma, keloid or melanoma among others. Microscopically, the detached portion was a CD34-positive dermal spindle cell proliferation with a fascicular and storiform pattern and a positive deep margin, consistent with dermatofibromaprotuberans (DFSP). Due to the large size and indistinct clinical borders, Mohs micrographic surgery with three stages and a total of 51 sections was performed to ensure complete removal of the tumor. DFSP usually presents as a slow growing papule or nodule which can show necrosis, hemorrhage and accelerated growth, but autoamputation has not been described in the English literature

Autoamputation of Dermatofibrosarcoma Protuberans: A Novel and Rare Presentation of a Familiar Entity

Dermatofibrosarcoma protuberans (DFSP) is categorized as a fibrohistiocytic tumor of intermediate malignant potential. It has significant risk for local recurrence and, less commonly, local or distant metastasis. Initially, these tumors typically arise as a firm plaque on the skin that slowly progresses to a nodular and protuberant dermal lesion. DFSP can also exhibit ulceration, hemorrhage, and accelerated growth, but autoamputation has not been described in the English literature. In this article, we report a case of an asymptomatic classical DFSP on the upper back in which the protuberant portion spontaneously autoamputated. In this case, the residual lesion was treated with Mohs micrographic surgery. The presentation, features, and implications of this interesting mode of presentation are discussed

Head and neck low-grade fibromyxoid sarcoma: A clinicopathologic study of 15 cases

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon mesenchymal tumor usually arising in the lower extremities and trunk. Only rare examples in the head and neck region have been reported. Fifteen cases of head and neck LGFMS were retrieved. MUC4 was performed on all cases. Results for smooth muscle actins, β-catenin, desmin, S100 protein, Epithelial membrane antigen (EMA) and STAT6 immunohistochemistry, as well as FUS rearrangement status, were recorded when available. Sites included neck (8), supraclavicular region (4) and orbit (1), parapharyngeal space (1) and lower lip (1). The age of the patients ranged from 3 to 97 years (median, 26 years). Tumors displayed classical morphologic features of LGFMS, as described. All cases (15/15) were positive for MUC4, and all cases tested (4/4) harbored FUS rearrangement. Variable positivity for EMA was identified in one case. Follow-up was available in 11 patients, ranging from 2 to 240 months (mean 71.4 months; median, 44 months). Three tumors recurred locally; none metastasized. In conclusion, although distinctly uncommon, LGFMS may arise in the head and neck region and should be distinguished from other more common spindle cell tumors in these locations. The morphologic, immunohistochemical and molecular genetic features of head/neck LGFMS are identical to those occurring elsewhere. The long-term metastatic risk of LGFMS in these locations remains to be fully elucidated

Revisiting the cytologic features of autoimmune pancreatitis: An institutional experience

BACKGROUND: Autoimmune pancreatitis (AIP) is a known mimicker of pancreatic ductal adenocarcinoma both clinically and radiologically. In this study, the authors present their institutional experience in diagnosing AIP on cytology and correlate results with the histologic findings. METHODS: A 14-year computerized search for patients who had histologically confirmed AIP with concurrent or prior cytology was performed. Clinical data, cytology findings, and surgical pathology results were reviewed for analysis. RESULTS: Eighteen patients were identified. The patients showed a male predominance, with a mean age of 59 years. Jaundice, weight loss, and abdominal pain were the most common clinical presentation. Five of 12 patients who were tested for serum immunoglobulin G4 had elevated levels. Cytologic findings of 16 cases that were available for review showed markedly inflamed fibrous stroma (54%) and cytologic atypia (50%). The final cytologic diagnoses were suspicious for adenocarcinoma (n = 1), atypical (n = 8), and benign/negative (n = 9). The corresponding surgical pathology diagnoses were classified as type 1 (n = 10), type 2 (n = 6), and AIP, not otherwise specified (n = 2). All type 2 AIP cases had at least atypical cytologic diagnoses, with one called suspicious for adenocarcinoma and another called adenocarcinoma at the time of rapid on-site evaluation. In contrast, eight of 10 type 1 AIP cases were negative/benign, and two of 10 were atypical. In these two atypical cases, the possibility of AIP was raised because of the presence of inflamed stroma. CONCLUSION: AIP is a pitfall in cytology because moderate-to-marked atypia can be present, especially in type 2 AIP. Because atypia can be severe, the presence of cellular fibrous stroma with lymphocytic stromal infiltrates and the integration of serum immunoglobulin G4 levels could be helpful in avoiding diagnostic overcall in AIP

Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma With Features Mimicking Spindle Cell Lipoma

Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) and spindle cell lipoma are lipomatous tumors with distinct clinical, molecular, and prognostic features. Although histological and immunophenotypic features can overlap between ALT/WDL and spindle cell lipoma, the oncogenesis and clinical behavior are markedly different. In borderline cases, molecular analysis for MDM2 or CDK4 amplification can aid in distinguishing ALT/WDL from spindle cell lipoma. Although dedifferentiated liposarcoma has been reported to harbor both MDM2 amplification and loss of the RB1 region, we are not aware of a reported RB1 loss in well-differentiated ALT/WDL. In this article, we present a 69-year-old woman with a lipomatous tumor in the gluteal region that histologically, immunohistochemically, and molecularly mimicked spindle cell lipoma (with positive immunohistochemical staining for CD34 and loss of the RB1 gene region), yet harbored amplification of MDM2 and CDK4 confirmed by fluorescence in situ hybridization, supporting classification as ALT/WDL. This case strengthens the argument that in atypical clinical contexts, molecular studies for MDM2/CDK4 should be considered in tumors resembling spindle cell lipoma

Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract are genetically different from nodular fasciitis and lack USP6, ROS1 and ETV6 gene rearrangements.

AIMS: Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract have a debatable relationship with inflammatory myofibroblastic tumour (generally lacking ALK rearrangement); however, they share several overlapping features with nodular fasciitis of soft tissue. As rearrangement of the USP6 gene has been recently recognised as a recurrent alteration in soft tissue nodular fasciitis, and several other alternative gene fusions have been recently recognised in inflammatory myofibroblastic tumour, the aim of this study was to investigate whether USP6, ROS1 or ETV6 rearrangements were present in these lesions (12 cases). METHODS AND RESULTS: Fluorescence in-situ hybridisation analysis was performed by the use of bacterial artificial chromosome-derived break-apart probes against USP6, ROS1, and ETV6. Two cases with adequate genetic material from recent paraffin tissue blocks were also tested by use of a solid tumour gene fusion detection assay via next-generation sequencing, targeting \u3e50 known genes involved in recurrent fusions. None of the genitourinary pseudosarcomatous myofibroblastic proliferations was found to harbour USP6 (0/12), ROS1 (0/8) or ETV6 (0/7) rearrangements, and no gene fusions were detected in two cases studied by sequencing. CONCLUSIONS: Despite overlap in histological and immunohistochemical features between pseudosarcomatous myofibroblastic proliferation and nodular fasciitis, these tumours lack the recently recognised USP6 rearrangements that occur in nodular fasciitis, as well as alternative fusions found in ALK-negative inflammatory myofibroblastic tumours. At present, this diagnosis remains based primarily on clinical, histological and immunohistochemical features