Epithelioid Hemangioendothelioma Presenting as a Leg Mass: A Rare Vascular Tumor Presenting Diagnostic and Management Challenges

Abstract

Introduction: Epithelioid haemangioendothelioma (EHE) is a rare vascular neoplasm of endothelial origin with biological behaviour intermediate between benign haemangioma and malignant angiosarcoma. Owing to its rarity, variable clinical presentation, and histopathological overlap with other soft-tissue tumours, its diagnosis and management can be challenging. Current evidence is limited, with most available literature derived from case reports and small case series. Case Presentation: A 48-year-old woman presented with a slowly growing, painless soft-tissue mass over the posterior aspect of the left leg that had been present for seven months. Initial clinical assessment suggested a benign soft-tissue lesion; however, ultrasonography and magnetic resonance imaging raised suspicion of a soft-tissue sarcoma. Core biopsy demonstrated features suggestive of myxoid sarcoma. Further histopathological examination revealed a hypercellular neoplasm composed of cords, strands, and small nests of epithelioid cells within a myxohyaline stromal background, with occasional intracytoplasmic vacuoles. Immunohistochemical staining was positive for the endothelial markers CD31 and CD34, confirming the diagnosis of soft-tissue EHE. The patient underwent wide en bloc surgical excision with negative margins (R0 resection). The postoperative course was uneventful, and the wound healed completely. Surveillance contrast-enhanced computed tomography (CT) of the chest and abdomen demonstrated no evidence of metastatic disease. The patient was followed at three-month intervals for one year, with no evidence of local recurrence or distant metastasis. Discussion: Soft-tissue EHE is an uncommon vascular tumour with unpredictable biological behaviour, ranging from localised disease to metastatic presentation. Accurate diagnosis requires correlation among clinical, radiological, histopathological, and immunohistochemical findings. Differentiation from epithelioid angiosarcoma and epithelioid sarcoma is essential because their prognoses and treatments differ. For localised, unifocal EHE, complete surgical excision with adequate negative margins remains the mainstay of treatment. The role of adjuvant therapy remains unclear because of limited evidence. Conclusion: EHE should be considered in the differential diagnosis of soft-tissue masses with atypical clinical or radiological features. Complete surgical resection with negative margins can provide effective local control in localised disease; however, long-term surveillance is necessary because of the potential for recurrence and metastasis.