Psoriasiform Keratosis is a rare clinic entity. The etiopathogenesis remains unknown and the disease is characterized by a solitary, scaly or keratotic papule, or plaque mainly located on the extremities. Histopathological features closely resemble those of psoriasis. We report the case of a 70-year-old woman presenting a solitary and asymptomatic keratotic plaque, located on the back of the left leg, unresponsive to topical corticosteroids. We performed an excisional biopsy and histopathology was consistent with psoriasiform keratosis.

O Pioderma gangrenoso é uma doença inflamatória rara, crônica e recorrente, de etiopatogenia desconhecida, caracterizada por uma ulceração não-infecciosa, necrotizante e dolorosa da pele. Geralmente, afeta adultos na faixa de 25 a 54 anos e raramente crianças (menos de 4%), nestes acomete preferencialmente cabeça e face, nádegas, região perianal e genital. Apresenta rápida resposta à corticoterapia sistêmica. Relata-se um caso de recém-nascida com lesões ulceradas de pioderma gangrenoso de fundo hemorrágico e necrótico distribuídas em abdômen, região genital e glútea com resposta rápida e efetiva à prednisona oral.

Pyoderma gangrenosum is a rare, inflammatory, chronic and recurrent disease of unknown etiology, characterized by noninfectious, necrotizing and painful cutaneous ulcers. Usually it affects adults aged between 25 and 54 years old and rarely children (less than 4%), in which it mainly affects the head, face, buttocks, genital and perianal region. The disease presents a quick response to systemic corticosteroids. We report a case of a newborn with hemorrhagic and necrotic ulcers, distributed in the abdomen, buttocks and genital region with rapid and effective response to oral prednisone.