Febrile ulceronecrotic Mucha–Habermann disease: proposed diagnostic criteria and therapeutic evaluation

Febrile ulceronecrotic Mucha–Habermann disease (FUMHD) is a rare severe variant of pityriasis lichenoides et varioliformis acuta characterized clinically by aggressive ulceronecrotic skin lesions associated with high fever and histologically by features typical of pityriasis lichenoides et varioliformis acuta. Despite the continuous addition of new case reports, no definite diagnostic criteria have been established, and an optimum treatment is still waiting. Herein, we review the different aspects of this rare entity, including pathogenesis, clinical and histopathological features, differential diagnosis, course, prognosis, and outcome. Different diagnostic and therapeutic challenges associated with FUMHD are also evaluated and discussed. We propose two sets of diagnostic criteria to define the disease more precisely and to avoid missing cases. The first comprises constant clinical and histopathological features that are always present in every case, the combination of which is necessary for diagnosis. The second set includes variable features that may be present in some cases and to which any emerging finding could be added. Although different therapeutic options have been used, there is no optimum therapy for FUMHD, and the disease still represents a therapeutic challenge.