Bullous pemphigoid with neurofibroma-like histopathological change in two patients without neurofibromatosis type 1: Coincidence or association?

The author reports two cases of Bullous pemphigoid (BP) with neurofibroma (NF)-like histopathological change. The two patients without neurofibromatosis type 1 (NF1) presented with several bullae on their trunk. Based on the results of positivity for anti-BP180 antibody, direct immunofluorescence, and histopathological findings, they were diagnosed with BP. Histologically, another lesion in the dermis, which was composed of spindle cells with wavy nuclei, collagen fibers, and mast cells, was located close to the bulla. Immunohistochemically, the spindle cells were diffusely positive for S-100 protein and CD34, and weakly positive for epithelial membrane antigen in certain foci. These findings were considered to be "NF-like" histopathological change. This is the first two cases of BP with NF-like histopathological change in patients without NF1.