The association and coexistence of plaque psoriasis and bullous pemphigoid is a rare clinical variant. It predominates in the male sex, after 60 years old. In general, patients already have a history of psoriasis and then bullous disease is added, with an average interval of 20 years. Although the pathogenesis is not yet fully established, it identifies triggers such as PUVA, drugs, and infections. Therapeutic options consist of monotherapy or combination regimens of systemic corticosteroids and other immunosuppressants such as methotrexate, with favorable evolution in most cases.

We present the case of a 52-year-old male patient with 3-year history of vulgar psoriasis and recent appearance of bullous pemphigoid of two months of evolution. The dermatological evaluation revealed a generalized dermatosis, with predominance of limbs, abdomen and trunk, which spared mucous membranes and genitalia; consisting of multiple scaly erythematous plaques, the scales were whitish, thick, adherent,  and settled on an erythematous and pruritic base. These lesions were surrounded by numerous tense blisters, with serous content, some of them unroofed and covered by a serohematic crust. Nikolski's sign was negative. Complementary tests were requested and normal. Histopathological study showed marked regular acanthosis, parakeratosis, predominantly neutrophilic inflammatory infiltrate, with deroofing of the epidermis.  In the immunofluorescence (IFD), immune deposits could be observed in the basement membrane area of C3 and IGA in a linear and continuous manner. The clinical and the anatomopathological findings and the immunohistochemistry, allowed us to arrive at the diagnosis of bullous pemphigoid, associated with psoriasis vulgaris. Treatment was started with corticosteroids at doses of 1 mg/kg combined with Methotrexate 15 mg/week for two months, then after two years, he continues with methotrexate monotherapy without complications or recurrences.