Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

Pseudomyogenic hemangioendothelioma (PHE) is a rare intermediate-grade vascular neoplasm that presents like a variety of clinicopathologically conditions. It more commonly affects adult males with approximately two-thirds of cases presenting as multifocal tumours that involve different tissue depths in the same anatomic region. We describe a rare case of widespread disseminated PHE. A 23-year-old male presented with a right arm papule which evolved over one month into multiple painful, erythematous lesions with associated myalgia but no other systemic symptoms. On examination, these were distributed in the upper and lower limbs, trunk, neck and face. PET/CT scan confirmed widespread hypermetabolic cutaneous and subcutaneous lesions, multiple intramuscular lesions, and destructive lytic lesions in the skull, axial and appendicular skeleton. MRI brain demonstrated a large lytic frontal bone lesion extending into the dura. Histology from right arm and knee skin punch biopsies showed an infiltrating undifferentiated epithelioid cell tumour. Immunohistochemistry demonstrated vascular differentiation with a pattern consistent with PHE. Diagnosis was confirmed by next generation sequencing molecular study identifying ACTB-FOSB fusion. There is currently no established standard of care for PHE. For multifocal involvement, systemic therapies have been described including cytotoxic chemotherapy, bone antiresorptive agents, mammalian target of rapamycin (mTOR) inhibitors, tyrosine kinase inhibitors (TKIs) and vascular endothelial growth factor (VEGF) inhibitors. Our patient was treated with combination sirolimus and zoledronic acid with resolution of symptoms and complete regression of several lesions, but ongoing fluctuating PET hypermetabolism in most lesions elsewhere. This case highlights the importance of distinguishing widespread disseminated PHE from high-grade malignancy.

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Karen Cheung