Primary Epithelioid Angiosarcoma of Finger Masquerading as Epithelioid Hemangioma: Report of a Case and Analysis of Mutational Pattern in Epithelioid Hemangiomas and Angiosarcomas by Next-generation Sequencing.

AIMS: We report an unusual case of epithelioid angiosarcoma (AS) mimicking an epithelioid hemangioma (EH) and analyze mutational patterns in EHs and ASs.

METHODS AND RESULTS: A 58-year-old woman presented with a finger lump and metastatic lung nodules. Initial needle biopsies showed an EH, with only focal atypical histologic features. The patient underwent finger amputation and resection of lung nodules. The amputation specimen and lung nodules revealed features of AS. Fluorescence in situ hybridization for FOS and FOSB gene rearrangements were negative in the primary tumor as well as in the lung metastasis. Intrigued by the unique morphologic features of an AS masquerading as an EH, we expanded our study by analyzing mutations in EHs versus ASs using a targeted next-generation sequencing of 50 cancer-related genes. Seven EHs and 6 ASs including the present case were subjected to mutation analysis using the Ion AmpliSeq Cancer Hotspot Panel v2 assay of 50 cancer-related genes. The present case lacked mutation. Novel somatic variants were detected in 2 of 7 EHs and 1 of 6 ASs. Sorting intolerant from tolerant and polymorphism phenotyping analysis revealed benign/tolerated and deleterious variants in both tumor types. Deleterious variants TP53 c.707T>C (p.Tyr236Cys), FLT3 c.1995C>T (p.Met665Ile), and SMO c.1919C>T (p.Thr640Ile) were detected in EH, while AS revealed deleterious variant PTPN11 c.226G>A (p.Glu76Lys).

CONCLUSIONS: We present an epithelioid AS mimicking EH. We report novel somatic variants in EHs and AS. Benign variants may not be associated with development of these tumors. Whereas, deleterious variants, especially PTPN11 c.226G>A, may be linked to tumorigenesis of AS.