Endocrine Abstracts

Background: Granulomatous mastitis (GM) is a rare inflammatory condition of the breast typically affecting women during postpartum period. GM can mimic inflammatory breast cancer and only be reliably distinguished through histopathology. While there is no generally accepted treatment for GM, therapeutic options include - antibiotics, wide surgical excision, and corticosteroids.

Clinical Case: A 54-year-old female presented to her family physician with with a warm, erythematous lump on the right breast. She was prescribed a 7-day course of antibiotics and referred to the infectious disease clinic. A subsequent biopsy confirmed acute and chronic granulomatous inflammation and gram-positive cocci. She responded to the antibiotic therapy, but her symptoms recurred and was prescribed a 2-month course of doxycycline but her GM symptoms failed to resolve. She had an over 10-year history of hyperprolactinemia thought to be due to chronic opioid therapy and was referred to Endocrinology for further assessment. Serum prolactin (PRL) level had ranged between 63 to 81 µg/l (5-25 µg/l) and the sella MRI was normal. The patient declined to stop opioid therapy and considering the possibility of PRL-induced GM, she was prescribed cabergoline 0.5 mg once weekly. Her GM symptoms rapidly resolved and she has remained asymptomatic.

Discussion: This case represents a rare occurrence of acute on chronic GM in the setting of longstanding drug-induced hyperprolactinemia. A review of literature revealed three other cases of drug-induced hyperprolactinemia associated with GM and four cases were prolactinoma. The underlying etiological role of PRL in GM is not fully understood, but it is believed to have immunomodulatory effects, potentially triggering an inflammatory response in the breast tissue. This report emphasizes the importance of considering hyperprolactinemia in the diagnosis and treatment of GM, particularly in cases of recurrent GM.