Idiopathic / Chronic Granulomatous Mastitis (IGM) Quick Review

  • Idiopathic (Chronic) Granulomatous Mastitis:
    • Is a rare, benign, chronic, inflammatory breast disease:
      • First described in 1972 by Kessler and Wolloch
    • Patients presenting with symptomatic idiopathic granulomatous mastitis:
      • Are young, usually non-white women (hispanics and African Americans) of reproductive age, typically with a recent pregnancy within the last five years
    • It is characterized histologically by:
      • Non-caseating granuloma formation within the breast lobules
      • Neutrophilic micro abscesses
  • The most common presenting symptom is:
    • A unilateral, firm, and discrete breast mass:
      • Which may be accompanied by:
        • Overlying skin changes and / or possible lymph node involvement:
          • With idiopathic granulomatous mastitis
    • The lesion may occur in any quadrant of the breast:
      • But often extends radially from the retro-areolar region
    • The average duration of symptoms was:
      • 3.9 months
    • The most common signs and symptoms include:
      • Discrete mass:
        • Usually unilateral
        • Firm
      • Tenderness to palpation
      • Erythema
      • Swelling
      • The pain could be out of proportion to findings:
        • Suggestive of a localized ischemic etiology:
          • The pain was the motivating factor in prompting all symptomatic patients to seek consultation
  • Possible etiology:
    • Extravasated lactation secretions:
      • May be responsible for eliciting a granulomatous inflammatory response in the lobular connective tissue
    • Local trauma, autoimmune processes, or chemical agents, such as oral contraceptive drugs and smoking:
      • May cause extravasations of luminal content:
        • With induced ductal epithelial damage
  • The disease often presents in:
    • Women of childbearing age:
      • Mean age in some studies is around 31.7
        • With a recent history of pregnancy or ongoing lactation
  • Typical mammographic and ultrasonographic findings of granulomatous mastitis include:
    • Segmental masses with ill-defined margins:
      • With tubular structures extending from the mass:
        • Which is heterogeneously hypoechoic
  • Mammographic findings of idiopathic granulomatous mastitis have ranged from:
    • Ill-defined mass to an asymmetric density without specific margins
    • It is usually not accompanied by:
      • Micro-calcifications or architectural distortion
    • Mammography in young patients:
      • Can be highly unspecific and misleading:
        • Due to the dense nature of the breasts
    • On the other hand:
      • A dense, spiculated mass causing asymmetry:
        • Raises concern for malignancy
  • Ultrasound may be useful to help differentiate between benign versus malignant etiology:
    • Ultrasound findings of idiopathic granulomatous mastitis include:
      • A hypoechoic heterogeneous mass with internal hypoechoic tubular structures:
        • Where tubular structures may be clustered, separate or contiguous:
          • The latter is consistent with inflamed ducts
          • Altogether, these are highly suggestive of the diagnosis, but also suggestive of abscess formation
  • The presence of associated imaging features such as:
    • A radial scar, micro-calcifications, or intra-ductal papilloma:
      • Steer the direction of further workup to favor biopsy:
        • Since these entertain the possibility of malignancy
  • Cultures sent and / or acid fast staining of mass aspirate has revealed:
    • Corynebacterium species:
      • There is evidence to suggest a link to Corynebacterium kroppenstedtii infection or colo- nization.
    • Propionibacterium acnesdall skin flora
  • Because surgical biopsy is more invasive and leaves a scar on the breast:
    • It is usually considered as the last choice after FNAB or CNB has failed
  • First line treatment:
    • Trial of antibiotics:
      • Most commonly with a short (two week) course of beta-lactamase resistant penicillin:
        • Assuming the more common mastitis at initial presentation
      • First-line therapy with doxycycline:
        • 100 mg twice daily:
          • Was successful as a first-line therapy:
            • With complete response in 50% of patients
  • Second line therapy:
    • Corticosteroids
    • Methotrexate appeared to be a successful second-line therapy:
      • In patients with disease that was refractory to doxycycline (complete response in 50%)
  • The overlap of presenting symptoms with other disease processes such:
    • As malignancy, acute or chronic infections, and chronic inflammatory dis- eases:
      • Makes definitive diagnosis difficult
  • Because the differential diagnosis may include malignancy:
    • The patient may experience significant anxiety during the evaluation
  • The broad differential differential and the lack of pathognomonic features:
    • Make definitive diagnosis difficult:
      • Often resting as a diagnosis of exclusion on a clinical basis:
        • Because diagnosis is difficult, patients typically have received:
          • Prolonged courses of antibiotics, frequent biopsies, or surgical procedures
  • Once the diagnosis is made:
    • Treatment strategies are not clearly delineated but are often supportive
  • IGM occurs predominantly in:
    • Hispanic women of childbearing age
  • IGM has major implications for quality of life:
    • With a high prevalence of pain and scarring
  • Although surgical therapy for IGM has been suggested in the literature:
    • Adequate medical management may alleviate the need for surgical intervention in some cases

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