Mast cell activation in Dowling–Degos disease

Dowling-Degos disease: a review

Dowling-Degos disease is a rare autosomal dominant genodermatosis. It is characterized by acquired reticulate hyperpigmentation over the flexures, comedone-like follicular papules, and pitted perioral scars that usually develop during adulthood. Mutations in genes affecting melanosome transfer, and melanocyte and keratinocyte differentiation have been implicated in the pathogenesis of this disease. These genes include KRT5, POFUT1, POGLUT1 and, most recently, PSENEN. Dowling-Degos disease can be found in isolation or with other associated findings, most notably hidradenitis suppurativa. This condition belongs to a spectrum of conditions that all result in reticulate hyperpigmentation that at times are hard to distinguish from each other. The most closely linked entity is Galli-Galli, which is clinically indistinguishable from Dowling-Degos disease and can only be distinguished by the presence of acantholysis on microscopy. Unfortunately, Dowling-Degos disease is generally progressive and recalcitrant to treatment.

Scrotal Dowling-Degos disease caused by a novel frameshift variant in gamma-secretase subunit presenile enhancer gene

We reported a Chinese pedigree with scrotal Dowling-Degos disease and evaluated the phenotypic and genotypic characteristics. In affected cases, pigmented macules were identified on the scrotum. The rashes increased, and the colour deepened progressively. No pain or pruritus were noticed, and no other skin folds were involved. Skin histopathology showed characteristic features of Dowling-Degos disease. A heterozygous PSENEN frameshift variant c.292delC（p.L98Wfs*47） was identified in affected cases. The variant was not found in dbSNP, 1000 Genomes project database and the ExAC Browser. The p.L98 and adjacent amino acids are highly conserved among species. Our cases expand the phenotypic and genotypic spectrum of PSENEN-related Dowling-Degos disease.