Idiopathic Granulomatous Mastitis

Idiopathic granulomatous mastitis (IGM):
- Is a rare benign inflammatory breast disease first described in 1972 by Kessler and Wolloch
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 average duration of symptoms is around 3.9 months with:
    - The most common signs and symptoms including discrete mass, tenderness to palpation, erythema, and swelling
    - The pain could be out of proportion to findings:
      - Suggestive of a localized ischemic etiology
    - The pain could be a motivating factor in prompting all symptomatic patients to seek consultation
- The lesion may occur in any quadrant of the breast:
  - But often extends radially from the retroareolar region
The disease often presents in women:
- Of childbearing age with a recent history of pregnancy or ongoing lactation:
  - The mean age of diagnosis is around 31.7 years and all within reproductive years
  - The high majority of women are Hispanic or African / African-American ancestry
  - A history of previous granulomatous disease (tuberculosis, sarcoidosis, autoimmune disease, or granulomatous disease) is very rare
The overlap of presenting symptoms with other disease processes such as:
- Malignancy, acute or chronic infections, and chronic inflammatory diseases:
  - Makes definitive diagnosis difficult
Because the differential may include malignancy:
- The patient may experience significant anxiety during the evaluation
In addition, the broad differential and the lack of pathognomonic features make definitive diagnosis difficult:
- Often resting as a diagnosis of exclusion on a clinical basis
The typical mammographic and ultrasonographic findings of granulomatous mastitis are:
- Mammogram:
  - Ill-defined mass to an asymmetric density without specific margins
  - It is usually not accompanied by microcalcifications or architectural distortion
Ultrasound:
- Heterogeneously hypoechoic lesion
- Segmental masses with ill-defined margins, with tubular structures extending from the mass:
  - The tubular structures may be clustered, separate or contiguous
Malignant features or findings:
- Suspicious microcalcifications, architectural distortion, or intra-ductal mass:
  - Would warrant appropriate histologic diagnosis and subsequent management
If the findings clinically and radiographically indicate an abscess:
- They warrant treatment with antibiotics along with drainage by aspiration or incision, if the abscess is larger
Idiopathic granulomatous mastitis is usually regarded as a sterile process:
- However, there is evidence to suggest a link to Corynebacterium kroppenstedtii infection or colonization:
  - This would then mandate routine cultures
- One-third of the patients with granulomatous mastitis who are evaluated:
  - Have findings suggestive of an abscess
Because diagnosis is difficult, patients typically have received:
- Prolonged courses of antibiotics, frequent biopsies, or surgical procedures
With a lack of pathognomonic imaging findings associated with granulomatous mastitis:
- Histopathology is key to confirming a diagnosis
Histologically:
- The disease has been described as non-caseating granulomas among epithelioid histiocytes and multinucleated giant cells surrounded by lymphocytes and plasma cells
- Histologic differentials begin with the use of:
  - Hematoxylin and eosin stains, gram stain, and may also include acid fast stains and Grocott’s methenamine silver to evaluate for the possibility of sarcoidosis or mycobacterium infection
Once the diagnosis is made, treatment strategies are not clearly delineated but are often supportive
Steroid treatment has been shown to decrease the extent of involvement, and enable complete resection with removal of less breast tissue should resection be pursued
- However, lower doses have also proven to be efficacious and help to avoid adverse effects of weight gain, hyperglycemia, and Cushingoid symptoms
- Regimens of 16 mg of prednisone twice a day for two weeks with a slow taper over a two-month period are described in the literature, as is prednisolone 30 mg/day for eight weeks, with taper
If symptoms do not improve, a course of methotrexate could be utilized:
- Since there is a contingent who feel that this disease is an abnormal immune response
- Success with methotrexate, including administration in steroid refractory cases:
  - Is limited to small studies of 3 to 5 patients
- In consideration of the duration of symptoms patients experienced, along with the lack of durable evidence favoring treatment with methotrexate, our institution favors proceeding directly to surgery in steroid-refractory cases
We recommend the surgical options of:
- Wide local excision for focal involvement and
- Total mastectomy with the option of reconstruction for diffuse involvement
- A 15% to 20% recurrence rate has been reported for surgery alone:
  - And inversely proportional to negative surgical margins
- In light of the fact that these masses are painful and may lead to fistula formation and deformity:
  - Intervention may be the preferred path to avoid progression or static disease
  - Our experience allowed for a trial of “conservative” medical management for two months:
    - Followed by treatment escalation for lack of progress
A course of methotrexate may be entertained in patients who desire continued attempts at medical management, to help preserve breast tissue
- However, it is not included in the first line of conservative management