URTICARIA PIGMENTOSA: A CASE OF PEDIATRIC RARE CUTANEOUS MACULOPAPULAR MASTOCYTOSIS

Abstract

Mastocytosis in children is a rare disorder characterized by an abnormal accumulation of mast cells in the skin and/or different organs Based on the site of mast cell accumulation, pediatric mastocytosis can be classified into two categories: cutaneous mastocytosis and systemic mastocytosis. The World Health Organization classification system differentiates three clinical variants of cutaneous mastocytosis: mastocytoma, urticaria pigmentosa also known as maculopapular cutaneous mastocytosis, and diffuse cutaneous mastocytosis. We present a clinical case of urticaria pigmentosa in an infant.

In January 2025, a five-month-old infant was referred to the University Clinic for Dermatology, due to the presence of multiple brownish macules disseminated across the trunk and upper extremities, accompanied by a mild degree of pruritus. The infant was generally healthy, born from an uncomplicated pregnancy, with no family history of dermatological diseases. The lesions were not present at birth. The first signs of pigmentation were noticed by the parents approximately three months prior, with a gradual increase in both the number and size. The dermatological status revealed the presence of more than 20 pigmented macules, each approximately 1 cm in diameter, localized on the trunk and upper extremities. A diagnosis of urticaria pigmentosa was established based on the clinical appearance and presence of positive Darier's sign, whereas a skin biopsy was unnecessary. The treatment regimen for the infant included only oral antihistamines. Long-term follow-up of this patient is needed, as the child has not yet reached puberty, in order to assess the severity and prognosis of the disease.