Scalp infestation by Pthirus pubis in a 91-year-old woman: A rare cause of chronic scalp pruritus.

Pthirus pubis is an ectoparasite that typically infests pubic hair and is primarily transmitted through close sexual contact. Although extragenital involvement may occur, scalp infestation remains exceptionally uncommon. We report the case of a 91-year-old woman who presented with a two-month history of persistent scalp pruritus that failed to respond to oral terbinafine and ketoconazole shampoo. Dermatological examination revealed numerous adult lice and nits attached to scalp hairs, with additional involvement of the eyelashes, eyebrows, and pubic region. Microscopic examination confirmed Pthirus pubis infestation. Screening for sexually transmitted infections was negative. Treatment with topical permethrin combined with oral ivermectin led to complete clinical and parasitological resolution. This case highlights the importance of considering Pthirus pubis in the differential diagnosis of chronic scalp pruritus, even in very elderly patients. Careful examination of all hair-bearing areas is essential to establish an early diagnosis and avoid inappropriate treatment.