Granulomatous mastitis with erythema nodosum: A breast cancer mimicking entity.

We present the case of a 42-year-old Hispanic patient who consulted with a left breast mass that showed clinical and imaging signs of breast cancer. During preprocedural examination before needle biopsy, the patient was found to have bilateral, purplish-brown skin lesions on her lower legs, suggestive of erythema nodosum. This clinical finding raised the diagnostic suspicion of granulomatous mastitis, which was later confirmed by histopathology. Granulomatous mastitis is a rare, nonmalignant entity that should be considered in patients of childbearing age who present with a breast mass. The coexistence with erythema nodosum contributes to the clinical suspicion of granulomatous mastitis; the mechanism of this association and the optimal treatment approach remain unknown.