Abstract Introduction Abrupt onset of papular lesions, with ulcero necrotic evolution could refers to many dermatitis. Febrile ulceronecrotic Mucha-Habermann disease is an unusual severe form of pitiriasis lichenoides and varioliform acuta (PLEVA) characterized with ulceronecrotic eruption potentially associated with high fever and systemic symptoms leading to death. Lymphomatoid papulosis is a recurrent papulonodular eruption with an initial presentation close to PLEVA. While this disorder usually has a bening course, about 10% of the patients develop lymphoproliferative disorders such as CD30+ lymphoma. Exegesis The authors reported an acute form of PLEVA in a young man hospitalized in internal medicine unit with fever and ulcero-necrotic papulo-vesicular lesions. Treatment with tetracycline was successful. They also report a case of lymphomatoïd pustulosis that occurred in a 34 years old woman with an extensive nodulo-pustular eruption characterized by central necrosis and ulceration. Histopathological examination revealed CD30 lymphocytic infiltration leading to diagnosis. Conclusion Theses two dermotosis, uncommun and clinically similar, are both characterized with an unpredictable evolution that to be known by internist.