Cutaneous nocardiosis: A great imitator.

Nocardiosis is caused by Gram-positive aerobic bacilli of the Nocardia genus, which are saprophytes living in the soil. It is a rare and opportunist disease with a localized or disseminated infection. When occurring in patients who are immunocompromised, involvement is usually systemic, most commonly represented by pulmonary disease. It can also be acquired through direct inoculation, entailing primary skin and subcutaneous tissue infections, frequently presenting as a localized nodular process. Cutaneous nocardiosis can manifest as a lymphocutaneous infection, actinomycetoma, superficial skin infection, or secondary infection from hematogenic dissemination. Diagnosis is made by identification of the organism in the culture of a clinical sample. Staining for acid-alcohol-resistant bacteria and, especially, Gram staining, is particularly relevant to obtain a rapid and presumptive diagnosis, while awaiting culture results. First-line medication is sulfamethoxazole-trimethoprim, which may be used with other antimicrobials, if necessary. Nocardiosis may be considered a major mimicker of several cutaneous diseases that present difficult, and often, delayed diagnoses.