La psoriasis es una enfermedad de la piel que se caracteriza por la presencia de lesiones papuloescamosas. Se presenta la historia clinica de una mujer de 38 anos de edad quien consulto por cuadro clinico de tres dias de evolucion, consistente en aparicion subita de lesiones tipo placas, eritematosas, descamativas, confluentes y generalizadas que llegaron a comprometer mas del 90% de la superficie corporal total. Estas lesiones eran de caracter pruriginoso y doloroso. La paciente presento signos de respuesta inflamatoria sistemica, dados por leucocitosis y taquipnea. Al revisar el caso, antecedentes, analisis y estudios de laboratorio de la paciente, se considero como impresiones clinicas: (A) psoriasis pustulosa de Von Zumbusch, (B) Sindrome de Steven Johnson secundario a ingesta de trimetropin-sulfametoxazol. La psoriasis pustulosa de Von Zumbusch es la variante de la psoriasis generalizada con mas riesgo de complicaciones severas. Rev. cienc.biomed. 2012;3(2):327-332 PALABRAS CLAVES Placas eritematosas; Psoriasis; Sindrome de Steven Johnson; Trimetropinsulfametoxazol. SUMMARY Psoriasis is a disease of the skin that is characterized by the presence of papular and scaly lesions. It is a clinical history of a woman of 38 years old who consulted for clinical manifestations of three days of evolution, consisting of sudden appearance of lesions such as erythematous, desquamative, confluents and widespread plaques that reached to compromise more than 90% of the total body surface. These lesions were of pruriginous and painful character. The patient had signs of systemic inflammatory response given by leukocytosis and tachypnea. To check the case, medical record, analysis and laboratory exams of the patient, it was considered as Clinical- Impressions: (A) Pustular psoriasis of Von Zumbusch. (B) Steven Johnson Syndrome secondary to an ingestion of Trimethoprim-sulfamethoxazole. Pustular psoriasis of Von Zumbusch is the variant of generalized psoriasis with more risk of severe consequences. Rev.cienc. biomed. 2012;3(2):327-332 KEYWORDS Erythematous plaque-like lesions; Psoriasis, Steven Johnson syndrome; Trimethoprimsulfamethoxazole.