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