Giant glomus tumor of the knee mimicking soft-tissue sarcoma
Glomangiomas (glomus tumors) are benign vascular tumors commonly located at the distal extremities, are usually subungual lesions, and account for 2% of all soft-tissue tumors. Patients with digital glomus tumors present with hypersensitivity to cold, paroxysmal severe pain, and point tenderness. These tumors are infrequent in the knee area, and when seen are superficial, usually have a diameter of less than 1 cm, which make their radiological diagnosis arduous. We report a noteworthy, unusual case of a large glomus tumor in the popliteal fossa showing biceps femoris infiltration, in a 51-year-old female patient who experienced severe intermittent posterior knee pain for the past 2 years. Magnetic resonance imaging revealed a large popliteal inhomogeneous soft-tissue lesion with irregular margins insinuating the posterolateral musculature mimicking soft-tissue sarcoma. Histopathology revealed a glomus tumor.
Keywords: Glomus tumor, Soft-tissue sarcoma, Glomangioma, Knee
Glomus tumor is usually a benign neoplasm. It is a perivascular mesenchymal tumor arising from the glomus body which is a thermoregulatory apparatus within the dermis. It is most commonly seen in subungual region of the finger but may occur anywhere. It is one of the characteristic fingertip masses that can be diagnosed with magnetic resonance imaging (MRI). These lesions occur in adults aged 20–40 years with subungual lesions showing female predominance. These tumors are infrequent in the knee area, and when seen are superficial, usually subcentimetric.