Bullous Prurigo Pigmentosa.

Prurigo pigmentosa (PP) is an inflammatory dermatosis with unknown etiology. The clinical presentations of PP varies according to the stages of the disease. Rarely, the formation of numerous vesicles and bullae upon erythematous infiltrative plaques can be found during the entire clinical course. In the present case, a 29-year-old Chinese woman presented with a 6-year history of relapsing pruritic erythematous plaques and bulla on her neck, chest and back. Physical examination revealed multiple erythematous plaques and vesicles in combination with mottled pigmentation in a symmetrical distribution and reticular pattern on the nape of her neck, chest and back. Histological examination of the biopsy specimen collected from the bullous area of her chest indicated a lichenoid reaction with intraepidermal bulla. This inflammatory region is characterized by recruitment of lymphocytes, spongiosis, and a perivascular lymphohistiocytic infiltrate in the upper dermis. Direct immunofluorescence analysis for IgG, IgA, IgM and C3 was negative. The diagnosis of bullous prurigo pigmentosa was verified based on the clinical manifestation and pathological findings. Minocycline hydrochloride therapy (100mg/d) was initiated, and 3 weeks later the rash had completely disappeared, which resulted in pigmentation of the entire area. No recurrence was observed during the 4 years follow-up.