Multifaceted Spindle Cell/Sclerosing Rhabdomyosarcoma With Role of Immunohistochemistry in Avoiding Misdiagnosis: A Multi-Institutional Study of 45 Distinct Tumors.

Background. Spindle cell/sclerosing rhabdomyosarcoma is a rare neoplasm and has an aggressive clinical course. Because of its rarity, we performed a multi-institutional collaboration to comprehend the overarching clinical, histopathological, and immunohistochemical characteristics of a cohort of spindle cell/sclerosing rhabdomyosarcoma. Materials and Methods. Forty-five patients with spindle cell/sclerosing rhabdomyosarcoma were identified. Demographics, clinical, histopathological, and immunohistochemistry data were reviewed and recorded. Results. The patients' age ranged from 1 to 85 years with a male to female ratio of 1.2:1. There were 15 children/adolescents and 30 adults. Eighteen (40%) tumors were located in the head and neck region. Twenty-four (53%) tumors displayed a bimorphic cellular arrangement with hypercellular areas having short, long, and sweeping fascicular and herringbone pattern, and hypocellular areas with stromal sclerosis and associated hyalinized and/or chondromyxoid matrix. Histomorphological differentials considered were leiomyosarcoma, malignant peripheral nerve sheath tumor, fibrosarcoma, nodular fasciitis, liposarcoma, synovial sarcoma, sarcomatoid carcinoma, solitary fibrous tumor, dermatofibrosarcoma protuberans, and schwannoma. Six tumors exhibited marked stromal sclerosis. The myogenic nature was confirmed by immunohistochemistry. Positivity for at least one skeletal muscle-associated marker (MyoD1 and/or myogenin) was observed. Conclusion. Spindle cell/sclerosing rhabdomyosarcoma diagnosis can be challenging as a number of malignant spindle cell neoplasm mimic this entity. Thus a correct diagnosis requires immunohistochemical work up with a broad panel of antibodies. In view of rarity of this neoplasm, further studies on a large cohort of patients with clinical follow-up data are needed for a better understanding of this tumor.

Primary dura-based synovial sarcoma of the parafalcine region of brain.

Dura-based intracranial neoplasms include a wide range of primary and metastatic tumors, varying in their clinical, radiologic, morphologic, and immunophenotypic characteristics. At this anatomic location, sarcomas are rare, however, they exhibit close morphologic resemblances to meningioma. Herein we describe the third case of primary synovial sarcoma of the parafalcine region in a50-years-old female, who presented with left-sided hemiplegia. The radiologic survey revealed a 5.5cm×5.8cm contrast enhancing dura-based mass at the right parafalcine region with meningeal enhancement and edema in the surrounding areas. Morphologic evaluation exhibited a high-grade spindle cell neoplasm, with focal hemangiopericytomatous pattern. The tumor cells were diffusely immunoreactive for CD99, Bcl2, TLE-1, and vimentin. The Ki-67 proliferation index was 40%. Pancytokeratin was focally positive. Epithelial membrane antigen, progesterone receptor, CD34, S-100, and glial fibrillary acidic protein were negative. Fluorescence in situ hybridization confirmed tumor specific translocation t(X;18)(p11.2;q11.2). Hence, final diagnosis of synovial sarcoma was rendered. Primary meningeal synovial sarcoma should be considered in the differential of aggressive and high-grade dura-based tumors in view of their relative chemosensitivity and future prospect of a molecular target-based therapy. The index case highlights the importance of an extensive pathologic analysis of high-grade mesenchymal lesions of the meninges to arrive at a definitive diagnosis and differentiate such tumors from other usual dura-based tumors, which has important therapeutic and prognostic implications.

Uterine angioleiomyoma: A rare variant of uterine leiomyoma--A case report and literature review.

Uterine angioleiomyoma (AL) is an extremely rare variant of leiomyoma and only 15 cases have been reported till date. Herein we present a case of AL of the uterus in a 39-year-old multiparous female with polymenorrhagia and pain abdomen. A pelvic ultrasonogram showed a large heterogeneously hypoechoic intramural nodule in the posterior myometrium. The patient underwent a total abdominal hysterectomy. Histological examination of the nodule revealed a moderately cellular spindle cell tumor composed of interlacing fascicles of spindle to plump cells swirling around the thick walled vessels. No hypercellularity, pleomorphism, mitotic figures, or necrosis was identified. The spindle to plump cells showed strong and diffuse immunoreactivity for smooth muscle actin, desmin and progesterone receptor, focal and weak positivity for CD10 and estrogen receptor and were negative for CD34 and HMB-45. The Ki-67 labeling index was low (1%). A diagnosis of AL was offered. The patient is on follow up for over 10 months and is asymptomatic.