A Knee Pain Referred to a Dermatologist

A painful lesion on the skin can arise from any of the cutaneous structures. A 51-year-old man presented with left knee pain of 1-year duration that got aggravated by contact with clothing or light touch. His symptoms failed to improve despite multiple visits to orthopedics and neurologists. On examination, a 1 cm × 2 cm tender nodular lesion was present on the left knee with surface scaling. Dermoscopy showed peripheral scaling with a rich vascular network interlaced with structureless white areas. The lesion was excised, and histopathology showed fibrocollagenous tissue along with a well-circumscribed encapsulated tumor composed of islands and nests of monomorphic cells with round centrally placed nuclei, reported as a glomus tumor. Post excision, the patient was asymptomatic, and no recurrence was observed. Glomus tumors are classically described to arise from fingertips or extremities. Atypical sites can also be involved, with very few cases reported in the literature.