Ostraceous psoriasis is a rare form of psoriasis, characterized by lesions with firmly adhered thick scales, in various colors, with surfaces resembling oysters shells. The protracted course of clinical presentation allied with peculiar lesions and histopathological examination permit the diagnosis. Lesions are usually resistant to topical medications, requiring systemic treatment. It is important that dermatologists are able to diagnose the unusual forms of psoriasis to avoid iatrogeny. We report the case of a patient with ostraceous psoriasis treated with methotrexate.

Schistosomiasis is best known in its visceral form but it can attack the skin, its ectopic cutaneous manifestation being rare and clinically difficult to diagnose. It is characterized by isolated or coalescent papules, erythematous, pruritic or asymptomatic, with zosteriform distribution, often located on the trunk. The authors report a case of a 28-year-old female patient with lesions on the abdomen, with positive stool results for Schistosoma and absence of active symptoms of visceral disease. The case reveals rare exuberant cutaneous manifestation and the importance of the diagnosis of this entity in patients from endemic regions.