Idiopathic plasma cell balanitis of Zoon in a 15-year-old boy.

Summary We report a 15-year-old boy with lesions mainly involving glans penis and prepuce, which appeared 4 years before. Histopathological study showed representative features of plasma cell balanitis of Zoon confirming this diagnosis. He presented a favorable outcome under topical tacrolimus 0.1%. The occurrence of this entity during childhood is extremely rare. Key words Zoon’s balanitis, plasma cells, childhood, tacrolimus. P lasma cell balanitis was first described by Zoon in 1950 (9). It is considered a chronic inflammatory benign mucositis. The majo-rity of the reported cases involved glans penis and/or prepuce of older uncircumcised men (8). We report a 15-year-old uncircumcised male who presented with idiopathic Zoon’s plasma cell ba-lanitis started 4 years before. This entity is extra-ordinarily rare in this age group. Case report A 15-year-old male patient was referred to the Department of Dermatology for evaluation of le-sions on his penis. He had no medical past histo-ry, and no previous treatments were reported. He stated they had appeared 4 years before, remai-ning completely asymptomatic. He denied any previous sexual contact and no other symptoms such as ulcer, fever or rash were acknowledged. On physical examination bright red, moist, non-palpable macular lesions were observed. Glans penis and prepuce were bilaterally and symmetrically involved in a mirror-like pattern (Fig. 1a). The lesions were also located near the preputial frenulum (Fig. 1b). No inguinal nodes were detected. Microbiological cultures were otherwise un-remarkable and a negative rapid plasma reagin (RPR) test excluded syphilis. Histopathological study showed a mild basal vacuolar alteration. Vascular proliferation was seen within the superficial and mid-dermis. A markedly dense, band-like, plasma cell-rich in-filtrate within superficial dermis (Fig. 2a, b) was observed. In addition, some lymphocytes were also noted.Immunostaining with primary antibody against