AUTHOR=Kita Kanako , Kurokawa Ichiro , Hayashi Daisuke , Hashimoto Takashi 

TITLE=Prurigo pigmentosa clinically and immunologically mimicking autoimmune bullous disease: A case report

JOURNAL=Frontiers in Medicine

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1047870

DOI=10.3389/fmed.2022.1047870

ISSN=2296-858X

ABSTRACT=A 15-year-old Japanese male noticed brown macules on his back nine months previously. Initial examination revealed reticulated infiltrative erythema and pigmentation with blisters on the erythema of the back. Histopathology showed blisters with eosinophil infiltration in the epidermis, and direct immunofluorescence detected weak C3 deposition in the epidermal basement membrane zone. Immuno-serological tests revealed the presence of immunoglobulin G (IgG) antibodies against  BP180, linear IgA disease antigen 1 (LAD-1), and laminin 3. The autoimmune bullous disease was suspected, and prednisolone at a concentration of 20 mg/day (0.3 mg/kg/day) was started. When the prednisolone dose was reduced to 10 mg/day, erythema and blisters recurred. The patient was diagnosed with prurigo pigmentosa based on clinical features and was treated successfully with oral doxycycline hydrochloride hydrate and topical tacrolimus ointment. This is the first case of prurigo pigmentosa with blisters in which autoantibodies to the epidermal basement membrane zone were found, which might be secondary non-pathogenic antibodies.