Unusual Facial "Acne": A Quiz.

A 31-year-old woman was investigated for multiple, slightly erythematous or flesh-coloured, firm, asymptomatic papu-les, a few mm in diameter, located exclusively on the chin and the lower part of both cheeks (Fig. 1a). These elements had gradually emerged over the 2 previous years and were initially considered and treated unsuccessfully as retentional acne. Physical examination was otherwise unremarkable and the general status of the patient was excellent. Histo-logical examination of a papule displayed a multi-nodular lymphocytic infiltrate of moderate density involving the upper and medium dermis that was well-limited laterally (Fig. 1b). Standard laboratory investigations and routine serologies, including serological diagnosis of Borrelia, were normal or negative. Computed tomography (CT) scan of the chest, abdomen and pelvis was unremarkable. What is your diagnosis? See next page for answer. Fig. 1. Clinical and histological features. (a) Multiple, small-sized papules of the lower part of the face with chronic evolution. (b) multi-nodular dermal infiltrate of moderate density involving the upper and medium dermis with reactive germinal centre-like structures (Haematoxylin-eosin ×5).