Granulomatous mastitis, erythema nodosum, and polyarthritis: a case report

Granulomatous mastitis is a rare inflammatory disease of the breast, typically seen in woman of child-bearing age. No definitive etiology has been described. In rare instances, this condition has been reported to be associated with extramammary manifestations such as erythema nodosum and arthritis. We describe this rare condition in an adolescent female. A 16-year-old, Hispanic female presented with right-sided painful breast swelling, polyarthritis, and erythema nodosum on bilateral shins and lower thighs. Physical examination was negative for lymphadenopathy and pulmonary, gastrointestinal, and cardiovascular findings. Ophthalmologic examination for uveitis and serologic tests for autoimmune diseases were negative. Diagnosis of idiopathic granulomatous mastitis was made by exclusion of other etiologies and conditions. Confirmation was made by histopathologic examination demonstrating noncaseating granuloma within breast lobules with neutrophils and microabscess formation. After wide local excision and a short course of trimethoprim-sulfamethoxazole, our patient was placed on naproxen and prednisone, the latter being tapered off over 3 months, with steady and complete resolution of all symptoms. This is the first reported case of idiopathic granulomatous mastitis in a pediatric patient who also had extramammary manifestations, including erythema nodosum and polyarthritis. In this case-based review, we summarize the phenotype, risk factors, prognosis, and treatment options of this rare condition, chiefly to make the readers cognizant of such a diagnostic possibility in similar clinical presentation in the future.