Intraosseous epidermoid cyst mimicking psoriasis.

Sir, We describe a patient with an intraosseous epidermoid cyst of her left little finger, which clinically mimicked psoriasis and radiologically raised concerns as regards a malignant bone tumour. A 24‐year‐old woman presented with a 7‐month history of a warty lesion on the tip of her left little finger (non‐dominant hand). An initial red swelling of the end of the digit was followed by a warty lesion that had started to lift the nail up, but was causing only minimal discomfort. A diagnosis of a common wart was made by her general practitioner, and treated with liquid nitrogen cryotherapy. On review a few weeks later, the warty lesion had increased in size with more erythema and swelling of the terminal digit, which had become more painful and with some limitation of movement. The patient was referred to the dermatology department. She had had two epidermoid cysts excised from her scalp previously. There was no other medical history of note and she was not taking any systemic medication. She gave a history of her mother and maternal aunt having psoriasis.