Trichoblastic carcinosarcoma: A case report and literature review.

Trichoblastic carcinosarcoma is a rare biphasic adnexal neoplasm. This case report chronicals the eighth occurrence of this tumor published in the English literature and provides a review of the prior publications. Clinically, this tumor presents as an isolated, rapidly growing lesion in elderly patients and is usually cured by complete surgical excision, with no evidence of recurrence or metastasis at follow-up (7/8 cases). Histopathologically, trichoblastic carcinosarcoma is dermal-based, with an epithelial component of basal cells and a mesenchymal component of spindle cells, both of which display malignant features. In addition to a morphologic description of trichoblastic carcinosarcoma, a discussion of the differential diagnoses, including other biphasic neoplasms, is also included. The small number of cases of trichoblastic carcinosarcoma is most likely secondary to under-recognition and underreporting and a larger case volume is needed to more accurately assess the clinical course and treatment strategies.

Epithelioid Hyalinizing Sarcoma With MGA-NUTM1 Fusion.

OBJECTIVES: Soft tissue sarcomas are a group of tumors derived from the mesenchymal origin. Historically, they have been classified according to morphologic and immunohistochemical characteristics. The advent of multiplexed next-generation sequencing (NGS), specifically RNA sequencing, has modified the classification of such tumors and others by determining categorization based on molecular alterations. The NUTM1 rearrangement, previously thought to be present only in carcinomas, has recently been reported in poorly differentiated high-grade sarcomas of the soft tissue. We present the first reported case of an epithelioid hyalinizing sarcoma harboring the MGA-NUTM1 fusion in an acral site. METHODS: Histopathologic, immunohistochemical, and molecular testing were performed on resection tissue. RESULTS: Histologically, the tumor showed an epithelioid morphology with prominent background hyalinization. Immunohistochemically, the tumor expressed CD99 and nuclear NUT-1. By NGS the tumor harbors MGA-NUTM1 fusion. CONCLUSIONS: Our findings support more extensive use of NGS for accurate sarcoma classification and identification of potential therapeutic targets. Furthermore, they corroborate the fact that NUTM1-rearranged soft tissue tumors represent a spectrum of heterogeneous morphologic entities. This case also highlights the utility of NUT-1 immunohistochemical study as a possible screening tool for NUTM1-fused sarcomas.