Transitory pigmented purpuric dermatoses in a young Japanese female

We report a 23-year-old female patient with a 4-month history of transitory pigmented purpuric dermatoses (PPD). She was otherwise healthy and reported no history of previous medication intake and none of her family members had any disorders. Clinical examination revealed well-demarcated, brownish hyperpigmented, reticulated pigmentation with pinhead-sized purpura. The histopathological specimen was characterized by a mild epidermal hyperkeratosis, elongated rete ridges, papillomatosis and mild mononuclear cell infiltration in the superficial dermis with focal extravasations of red blood cells without siderophage. Despite prominent extravasations of red blood cells and edema both in the papillary dermis and the subpapillary layer, no definite capillaritis was seen. Based on these clinicohistopathological findings, the diagnosis of transitory PPD was considered to be most compatible. Clinicians should recognize the unique but rarely acknowledged disease as a subtype of pigmented purpuric dermatoses.