Idiopathic granulomatous mastitis

Specialty: Gynecology and breast.

• Lobular granulomatous mastitis
• granulomatous inflammation of the breast
• chronic inflammatory breast disease

Why it occurs

• Localized autoimmune pathology of unknown basis (associated with hypersensitivity reaction to protein ductal secretions)
• Undetected chronic infection by Corynebacterium Kroppenstedtii or other atypical mycobacteria
• Persistent subclinical hyperprolactinemia
• Previous use of oral contraceptives in genetically predisposed patients

Initial workup

Bilateral mammography and high-resolution breast ultrasound (usually show masses with very irregular contours with confluent microabscesses and active fistulas, BI-RADS 4). The absolute confirmatory diagnosis is histological and requires core needle biopsy (CNB) or incisional biopsy that demonstrates non-caseating granulomatous inflammation centered on the breast lobes, after systematically ruling out breast tuberculosis (negative Ziehl-Neelsen stain and Löwenstein-Jensen culture) and fungal infections.

Standard management

• Prednisone starting with 0.5-0.8 mg/kg/day orally for 2 to 4 weeks, followed by a very slow and gradual tapering regimen over several months to avoid recurrences
• Methotrexate 10-15 mg orally once a week associated with folic acid 5 mg/week in cases refractory to corticosteroids or with contraindication for its use
• Cabergoline 0.5 mg/week if there is associated hyperprolactinemia (note: surgery should be reserved exclusively for the drainage of frank abscesses, since wide surgical resection is associated with a high rate of delayed healing and persistent fistulas).