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This report describes the clinicopathologic findings in 176 patients who presented with 178 tumors currently referred to as neurothekeomas. Our study group included 64 males and 112 females, ranging from 20 months to 85 years old at the time of their first surgical procedure (median age: 17 y). Twenty-four percent of patients were or=30 years of age at initial diagnosis. The patients typically presented with a solitary, superficial, slow-growing, and relatively asymptomatic mass in the 0.3 to 2.0 cm size range. One patient had multiple tumors. More than 75% of the lesions involved the head (n=63), upper extremities (n=44), and shoulder girdle (n=27) regions. The tumors were evident a few weeks to 4 years (median duration: approximately 7 mo) before surgical resection was sought. Histologically, the lesions involved the dermis and/or subcutis, and they formed multinodular masses with varying amounts of myxoid matrix and peripheral fibrosis. On the basis of the amount of myxoid matrix, the tumors were subclassified as cellular (n=63), mixed (n=67), or myxoid (n=48). All cases had spindled and epithelioid mononuclear neoplastic cells with relatively abundant cytoplasm and indistinct cell borders. The majority of cases also had occasional multinucleated tumor cells. The lesional cells had a strong tendency for whorled growth, and oftentimes, focal fascicular growth was also present. Nuclear atypia was minimal in 62 cases, mild in 73 cases, at least focally moderate in 41 cases, and focally marked in 2 cases. Mitotic activity ranged from 0 to 124 mitotic figures/25 wide-field high power fields (WHPFs) (median mitotic count: 4 mitotic figures/25WHPFs). Twenty-five lesions had >10 mitotic figures/25WHPFs. A total of 16 cases (9%) had atypical mitotic figures. Osteoclastlike giant cells were detected in 39% of cases. Immunoreactivity was typically present for vimentin, NKI/C3, CD10, microphthalmia transcription factor, and PGP9.5, and focal reactivity was sometimes noted for smooth muscle actin and CD68. All tumors tested were negative for S100 protein, glial fibrillary acidic protein, and Melan A. The overwhelming majority of cases had involvement of the tissue margins. A complete follow-up record is available for 71 patients (40.3%) with follow-up intervals ranging from 3 years 2 months to 34 years 9 months (median: 17 y 9 mo). Limited or incomplete follow-up information is also available for an additional 14 patients with follow-up intervals ranging from weeks to approximately 10 years (median: 5 mo). Regrowth of tumor after biopsy or local excision was reported in 13 patients, one of whom had 2 recurrences. However, because of the nature of our consultation practice and a tendency for clinicians to specifically send us cases with a complex clinical course, this is believed an overestimation of the true recurrence rate. Neurothekeomas are morphologically and immunohistochemically distinct from true nerve sheath myxomas. An origin from fibroblastic cells with the abili...

BACKGROUND. Aggressive angiomyxoma is an uncommon mesenchymal tumor

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Background. Extraskeletal osteosarcomas are rare malignancies that account for about 1% of all soft tissue sarcomas. Few large series have been reported. Methods. Clinical records and histologic slides of all patients with extraskeletal osteosarcomas treated at the Mayo Clinic between 1915 and 1988 were reviewed. Results. The study group consisted of 40 patients, most of whom presented in the sixth and seventh decades of life (mean age, 50.7 years). There was a male predominance (male‐to‐female ratio, 1.9:1). The lower limbs most commonly were involved (68%), usually the thigh and buttock regions. Ninety‐three percent of tumors presented as an enlarging soft tissue mass, with a history of trauma in nine patients. In nine patients, the lesions were initially interpreted histologically as benign, most commonly as myositis ossificans. Histologically, all were high grade osteosarcomas. Multiple local recurrences (45%) are a feature of this tumor. All recurrences occurred within 3 years. Distant metastasis (65%) is also common and is usually to the lungs (81%). Radical resections appear to be the best option for local control, with resection of the pulmonary metastasis occasionally producing a cure. By univariate analysis of Kaplan‐Meier survival curves, the patients with predominantly chondroblastic tumors fared better than those with predominantly osteoblastic tumors (P=0.03). Analysis of survival differences of the three main subtypes together (osteoblastic, chondroblastic, and fibroblastic) was not significant. A small‐sized initial lesion did not equate with better survival. Seventy‐three percent died of the disease, with a mean follow‐up of 5.9 years. Conclusion. Extraskeletal osteosarcoma is a high grade malignant tumor associated with a 5‐year survival rate of 37% (95% confidence interval, 28%–59%). Local recurrences and distant metastasis are common and usually occur by 3 years after excision. Patients with the chondroblastic subtype survive longer than those with the osteoblastic subtype. Cancer 1995; 76:2253–9.

Sox10 transcription factor is expressed in Schwannian and melanocytic lineages and is important in their development and can be used as a marker for corresponding tumors. Additionally, it has been reported in subsets of myoepithelial/basal cell epithelial neoplasms, but its expression remains incompletely characterized. In this study, we examined Sox10 express-ion in 5134 human neoplasms spanning a wide spectrum of neuroectodermal, mesenchymal, lymphoid, and epithelial tumors. A new rabbit monoclonal antibody (clone EP268) and Leica Bond Max automation were used on multitumor block libraries containing 30–70 cases per slide. Sox10 was consistently expressed in benign Schwann cell tumors of soft tissue and the GI-tract and metastatic melanoma, and was variably present in malignant peripheral nerve sheath tumors. In contrast, Sox10 was absent in many potential mimics of nerve sheath tumors such as cellular neurothekeoma, meningioma, gastrointestinal stromal tumors, PEComa, and a variety of fibroblastic-myofibroblastic tumors. Sox10 was virtually absent in mesenchymal tumors but occasionally seen in alveolar rhabdomyosarcoma. In epithelial tumors of soft tissue, Sox10 was expressed only in myoepitheliomas, although often absent in malignant variants. Carcinomas, other than basal cell type breast cancers, were only rarely positive but included rare squamous carcinomas of head and neck and pulmonary small cell carcinomas. Furthermore, Sox10 was often focally expressed in embryonal carcinoma reflecting a primitive Sox10-positive phenotype or neuroectodermal differentiation. Expression of Sox10 in entrapped non-neoplastic Schwann cells or melanocytes in various neoplasms has to be considered in diagnosing Sox10-positive tumors. The Sox10 antibody belongs in a modern immunohistochemical panel for the diagnosis of soft tissue and epithelial tumors.

Ossifying fibromyxoid tumor (OFT) is a unique soft tissue tumor of uncertain histogenesis. The majority of reported cases (approximately 220) have pursued a benign clinical course. However, recent literature has emphasized the existence of morphologically atypical and clinically malignant examples of this tumor and proposed guidelines for assessment of biologic potential. In the present study, we evaluated 104 cases of OFT from the Armed Forces Institute of Pathology, accessioned between the years 1970 and 2007. Herein, OFT was strictly defined as a tumor with lobular architecture, predominantly epithelioid cell morphology, a low level of atypia, corded and trabecular growth patterns, moderate amounts of myxocollagenous matrix, and often, focal peripheral metaplastic bone formation. Tumors that lacked conventional morphology were excluded. The exclusion group included cutaneous mixed tumors, low-grade fibromyxoid sarcomas, and extraskeletal osteosarcomas. The OFTs occurred in 64 men and 40 women with a median age of 50 years (range, 21 to 81 y). The tumor size ranged from 0.7 to 17 cm (median, 3 cm). The mitotic rate varied from 0 to 41 mitotic figures per 50 HPFs (median, 2/50 HPFs). Tumor cell nuclei typically contained small, distinct nucleoli, and necrosis was infrequent (11/104). The great majority of tumors (67/71, 94%) were positive for S100 protein, whereas only occasional examples had (focal) positivity for desmin, glial fibrillary acidic protein, and an AE1/AE3 keratin cocktail. Local recurrences were documented in 9 of 41(22%) living patients, usually 10 or more years after primary surgery, but there were no metastases. A mitotic rate of >2 mitotic figures/50 HPFs was a risk factor for local recurrence, but necrosis, tumor size, the presence of satellite nodules, and positive margins were not. When OFT is strictly defined by the criteria noted above, there is potential for local recurrence, but there seems to be little or no risk for metastasis.

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