Prurigo Pigmentosa: A Case Report With Unusual Presentation.

Prurigo pigmentosa (PP) is an idiopathic cutaneous inflammatory disorder. Here we report a 50-year-old healthy male of Arabic descent who presented with a six-month history of very itchy persistent skin lesions on his back. Skin examination revealed multiple brownish non-scaly excoriated papules and patches in the midline of his lower back. The differential diagnosis includes lichen planus (LP), confluent and reticulated papillomatosis (CARP), and PP. Skin biopsy revealed acanthosis, spongiosis, and dyskeratotic keratinocytes in the epidermis. The dermis showed mild perivascular lymphocytic infiltrate. Based on the previous clinicopathological findings, the patient was diagnosed with PP. He was prescribed doxycycline 100 mg once daily (OD) for two months. Two months after treatment, all lesions disappeared completely. After one year at the follow-up, he presented with a recurrence of the same skin lesions at the same site. We restarted him on doxycycline treatment.