Itchy plaques with associated comedonal openings and cysts

Abstract

A 55-year-old woman presented in 2016 with a slowly enlarging solitary itchy plaque on her left occipital hairline. It had become mildly tender and thickened over a 9-month period. The patient was otherwise well, and used only occasional salbutamol inhalers for asthma. Physical examination revealed an erythematous plaque 30 mm in size, within which were comedonal openings and small cysts, from which could be expressed a mucoid discharge (Fig. 1a). The lesion was initially biopsied, then subsequently excised due to diagnostic uncertainty, and healed well.The patient remained under annual dermatology follow-up with no new lesions until 3 years later in 2019, when she developed similar itchy lesions affecting her left temple and left postauricular areas (Fig. 1b-d). In the intervening time, the patient had been successfully treated for endometrial cancer with hysterectomy, with no other changes to her health. Further skin biopsies were taken from the lesions. The patient was subsequently diagnosed with polymyalgia rheumatica, for which a reducing dose of prednisolone was started. She had also noticed a new similar erythematous patch on her right forehead.