A Rare Presentation of Photodistributed and Flexural Hyperpigmentation in Galli-Galli Disease

Summary: Galli-Galli disease (GGD) is a rare autosomal-dominant genodermatosis and an acantholytic variant of Dowling-Degos disease (DDD). It is characterized by progressive reticulated hyperpigmentation, primarily in flexural areas, with histopathological evidence of suprabasal acantholysis. We report the case of a 45-year-old Brazilian female with a 15-year history of worsening photodistributed hyperpigmentation involving her chest, back, neck, and extremities, associated with pruritus and burning post-showering. Physical examination revealed reticular hyperpigmented macules with scattered erythematous keratotic papules, involving flexural and non-flexural regions. Histopathological analysis of punch biopsies demonstrated basket weave keratosis, mild epidermal hyperplasia, basal keratinocytic pigmentation, and suprabasal acantholysis, consistent with GGD. The patient’s symptoms were managed with topical triamcinolone and emollients, achieving partial symptomatic relief. This case highlights an unusual photodistributed presentation of GGD, broadening the clinical spectrum of this rare disorder. Accurate diagnosis relies on clinical suspicion, histopathological confirmation, and, where available, genetic testing for KRT5 or POGLUT1 mutations. Although standardized treatments are lacking, vitamin A derivatives and laser therapies may provide relief. This case emphasizes the importance of recognizing atypical presentations of GGD and integrating histological findings to differentiate it from closely related disorders such as DDD.