(BMJ)—A 47-yo man presented w/ a 1-yr hx of a mildly pruritic penile rash. Exam: well circumscribed, red, desquamating lesion on glans penis. No lesions on scalp, trunk, extremities, oral mucosa, or nails. Rapid plasma reagin, treponema pallidum particle assay, and HIV all negative. Bx confirmed dx. What is it?
Balanitis xerotica obliterans
Psoriatic balanitis
Carcinoma in situ
Angiokeratoma
Lichen nitidus
You are correct. Histology revealed hyperkeratosis, parakeratosis, and neutrophilic clusters in the stratum corneum, consistent w/ psoriatic balanitis. About 63% of pts w/ psoriasis vulgaris have genital involvement, but only 2% to 5% have lesions limited to the genitals. Uniformly distributed dotted vessels on a pale red background may be visible on dermoscopy, but bx provides the definitive dx.

BMJ 2019;365:l2063