A swollen, discoloured thumb.

Abstract

A woman aged in her 40s presented to Shanxi Provincial People's Hospital (Taiyuan, Shanxi, China) in January, 2020, with a 1-year history of a slowly swollen, discoloured, painful left distal thumb. No history of trauma or potentially systemic symptoms (eg, fever, cough, weight loss, or night sweats) was elicited. Physical examination showed a bulging thumbnail, clubbed fingertip, and a round, firm, immobile mass on palpation. There was abnormal 3 × 4 mm blue-black pigmentation at the lateral nail folds (figure, A). Joint mobilisation, skin temperature, and laboratory tests were normal. Radiograph showed a slightly expansile, ill-defined osteolytic lesion on the distal phalanx with cortical destruction and without matrix calcification or bony septae (figure, B).