Femoral Pseudomyogenic Hemangioendothelioma in 14-Year-Old Male - Case Report

Document Type

Conference Proceeding

Publication Date

11-2025

Publication Title

American Journal of Clinical Pathology

Abstract

Introduction/Objective: Pseudomyogenic hemangioendothelioma (PMHE) is a rare, locally aggressive vascular tumor that typically affects young adults’ soft tissue or bone and demonstrates limited metastatic potential. We report such a case in a 14-year-old male with detailed clinical history and pathologic correlations. Methods/Case Report: The patient initially presented with a pathological fracture of the left femur following a month-long history of hip pain. Imaging revealed multiple suspicious lytic lesions through - out the proximal femur, concerning for a neoplastic process. Open biopsy confirmed PMHE based on characteristic histopathology, including sheets of epithelioid and spindled cells with eosinophilic cytoplasm, and immunophenotype positive for keratin AE1/3, ERG, CD31, and FOSB, with negative CD34 and desmin stain. Despite initial surgical intervention with open reduction and pinning, the patient experienced significant local progression, requiring radical resection and reconstruction of the left proximal femur. Pathological analysis of the resected specimen confirmed a 7.5 cm tumor involving the bone and soft tissue, with a positive lateral soft tissue margin. NGS Sarcoma Fusion Panel confirmed an ACTB::FOSB fusion, thus supporting the diagnosis of PMHE. Results: NA Conclusion: This case underscores the diagnostic challenge and aggressive nature of PMHE, highlighting the importance of immuno- histochemistry and molecular testing for FOSB rearrangements in confirming the diagnosis.

Volume

164

Issue

Suppl 1

First Page

S4

Comments

American Society for Clinical Pathology (ASCP) Annual Meeting, November 17-20, 2025, Atlanta, GA

Last Page

S4

DOI

10.1093/ajcp/aqaf121.010

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