Chronic lichenoid pityriasis in an adolescent

Ariana Tavares, Department of Pediatrics, Unidade Local de Saúde Gaia/ Espinho in Vila Nova de Gaia and Unidade Local de Saúde Entre Douro e Vouga, Santa Maria da Feira, Portugal
Inês Azevedo, Department of Pediatrics, Unidade Local de Saúde Entre Douro e Vouga, Santa Maria da Feira, Portugal
André Coelho, Department of Pathology, UNILABS, Porto, Portugal
Miguel Costa, Department of Pediatrics, Unidade Local de Saúde Entre Douro e Vouga, Santa Maria da Feira, Portugal
Diogo Teixeira, Department of Pediatrics, Unidade Local de Saúde Gaia/ Espinho in Vila Nova de Gaia and Unidade Local de Saúde Entre Douro e Vouga, Santa Maria da Feira, Portugal

Introduction: Pityriasis lichenoides chronica (PLC) is a rare inflammatory skin disease, considered a subtype of pityriasis lichenoides. Although the etiology remains unknown, studies suggest it may result from a hypersensitivity reaction to an infection or represent a primary lymphoproliferative disorder, typically affecting children and adolescents. Case report: We present the case of a 15-year-old male adolescent with a five-month history of a recurrent, asymptomatic, and generalized rash. Dermatological examination revealed erythematous scaly oval papules, some with mild erosion, predominantly distributed over the abdomen and proximal extremities. Based on the suspicion of pityriasis lichenoides, a skin biopsy was performed, which confirmed the diagnosis. Treatment with topical corticosteroids resulted in significant clinical improvement with no recurrence during the 12-month follow-up period. Discussion: PLC is an uncommon condition that can pose diagnostic challenges due to its non-specific clinical manifestations, requiring careful differential diagnosis from other papulosquamous disorders. Although typically benign, annual dermatological follow-up is recommended due to the rare but potential risk of progression to cutaneous T-cell lymphoma.

Keywords: Chronic lichenoid pityriasis. Pityriasis lichenoides. Adolescent. Follow-up studies.