The thumb that wouldn’t heal: A diagnostic pitfall in subungual squamous cell carcinoma

Subungual squamous cell carcinoma (SSCC) is a rare malignant tumour arising from the nail bed, most commonly affecting middle-aged to older adults. Due to its indolent course and clinical resemblance to benign conditions such as chronic paronychia, onychomycosis and verruca vulgaris, diagnosis is often delayed. We report a 52-year-old male farmer with a 5-year history of a non-healing, painful lesion with recurrent pus discharge from the left thumb. The patient had undergone multiple nail avulsions and incision-drainage procedures without resolution. Imaging revealed cortical erosion of the distal phalanx, and histopathology confirmed SSCC. Positron emission tomography-computed tomography showed low-grade metabolic activity limited to the thumb, with reactive left axillary lymphadenopathy. The patient underwent distal phalanx disarticulation with local flap reconstruction. This case highlights the need for heightened clinical suspicion and early biopsy in chronic, treatment-resistant nail lesions to ensure timely and effective management.