Patch-type granuloma annulare mimicking bruises in a 9-year-old girl: first pediatric case report and literature review

Patch-type granuloma annulare (PGA) is a rare subtype of granuloma annulare (GA) characterized by a polymorphic presentation of smooth, erythematous to brownish macules. PGA is typically a disease of middle-aged and elderly adults. 53 cases have been documented since the entity was first described in 2000. We describe the first pediatric case of PGA, and we synthesize the existing literature on pathogenesis, clinical clues, and evidence-based therapy for this entity. A 9-year-old girl developed multiple asymptomatic, violaceous-brown patches measuring 1–5 cm in diameter on her thighs over six months. Biopsy results demonstrated abundant histiocyte and lymphocyte infiltration in the dermis, with scattered multinucleated giant cells, which were consistent with PGA. Topical corticosteroids produced no discernible improvement; however, the guardians declined further treatment. PGA predominantly affects elderly adults (median age 60 years), with female patients accounting for 86.8% of cases. The thigh is the most commonly involved site, and histopathological findings are consistent with interstitial granuloma annulare. The potential association with systemic disease–particularly malignancy in adults–warrants thorough evaluation and longitudinal follow-up. When topical corticosteroid therapy fails, phototherapy or JAK inhibitors represent viable alternatives. However, current evidence regarding malignancy risk and treatment efficacy derives primarily from adult literature; the applicability of these data to pediatric patients remains to be established.