Hemolymphangioma of the Knee: A Case Report of a Rare Vascular Malformation

Hemolymphangioma is a rare slow-flow combined vascular malformation composed of both lymphatic and blood vessels. This lesion has been documented in various anatomical locations, but its occurrence in the knee is exceedingly rare, with only one previously reported case. We present the case of a 28-year-old male with a 1-year history of progressive swelling in the medial right knee. Doppler ultrasound and magnetic resonance imaging suggested a vascular lesion. Surgical excision was performed and histopathological examination confirmed the diagnosis of hemolymphangioma, revealing dilated vascular spaces lined by endothelial cells, supported by immunohistochemistry positivity for CD34 and D2-40. The patient recovered well postoperatively with no recurrence at the 6-month follow-up. This case highlights the diagnostic challenges such rare lesions pose due to their nonspecific clinical and radiological features, often mimicking other more common knee pathologies. Consideration of vascular malformations in the differential diagnosis of knee mass is crucial for timely and effective management.