A 45 year old man with an ulcerated nodule on his right leg

A 48 year old man presented to our dermatology clinic because of an asymptomatic skin nodule on his right leg that had appeared several weeks earlier. He had no medical history of note. On further questioning, he mentioned that he had received an arthropod bite at that site during the previous summer. He was initially treated with a three week course of doxycycline 200 mg per day and topical mupirocin 2% as empirical treatment for Mediterranean spotted fever, which is endemic in our geographical area, pending the results of blood cell count, general biochemistry, and Borrelia burgdorferi serology. However, the main clinical symptoms of Mediterranean spotted fever—fever, weight loss, musculoskeletal pains, and neurological symptoms—were absent. On examination, chest, abdomen, and eye examinations were normal. The nodule on his anterior right leg was 4 cm in size, ulcerated, and indurated, with a raised border and central serous crust (fig 1⇓). Polarised non-contact dermoscopy of the nodule showed basal erythema, central ulceration, and hyperkeratosis with peripheral arborising telangiectasias, and peripheral “yellow tears” (fig 2⇓).