Purple plaques on the shin

While being investigated for tonsillar malignancy, this woman in her 60s was found to have a purple plaque on her right shin (fig 1, left) and multiple small, tender, bluish subcutaneous nodules that had arisen on both legs over the preceding two weeks (fig 1, right). She had a mild sore throat but no fever, weight loss, or night sweats. Histology of the left tonsil after tonsillectomy and biopsy samples from the skin on both legs showed primary tonsillar diffuse large B cell lymphoma (DLBCL) with secondary cutaneous involvement. Differential diagnoses include Kaposi sarcoma, sarcoidosis, and leukaemia cutis, which were ruled out on the basis of histopathology and immunohistochemistry. DLBCL is the most common type of non-Hodgkin’s lymphoma.1 Primary cutaneous DLBCL on the leg tends to occur in older women.2 Secondary cutaneous involvement in DLBCL may occur with more extensive skin lesions and indicates poorer prognosis compared with primary cutaneous DLBCL.3 4