Surgical management of idiopathic granulomatous mastitis; a single-center experience

Authors

Abstract

Aim
Idiopathic granulomatous mastitis (IGM) is a rare nonspecific inflammatory disease of the breast. Although IGM is completely benign, it can be confused with breast cancer because of breast mass and nipple retraction. This study aimed to investigate the clinical characteristics of 36 patients diagnosed with IGM, treatment options, and prognosis.
Methods
The study included 45 IGM patients with an average age of 36 years who were treated in our hospital from January 2012 to December 2020. Data were retrospectively collected from records. The relationship between categorical variables was analyzed using Pearson’s χ² test.
Results
All of our cases were premenopausal, and 14% had a smoking habit. The most common presentation was focal asymmetrical density on mammography and irregular hypoechoic mass on ultrasound. The mean size of the lesions was 5 cm. All cases had unilateral mass, and 58% of cases had right breast involvement. The most common localization was retroareolar/central location, with a rate of 42%. The presence of disease according to lesion localization differed significantly in favor of retroareolar/central localization in the chi-square analysis (p=0.001). Surgical excision was performed in 80% of patients.
Conclusion
Because of its similarity to malignant processes, it is crucial to confirm the definitive diagnosis by the presence of chronic lobular inflammatory process and non-caseating granulomatous inflammation on frozen sections. Our analysis determined that IGM was associated with the retroareolar/central localization of the main ducts. This likely supports the immune response secondary to ductal injury. Surgical excision and close follow-up were our preferred methods.

Keywords

Introduction

Idiopathic granulomatous mastitis (IGM) was first reported by Kessler and Wolloch in 1972 as 5 cases of mastitis clinically simulating carcinoma.¹ IGM can mimic breast cancer clinically and radiologically. Therefore, the awareness of surgeons, pathologists, and radiologists is vital to avoid unnecessary mastectomies.² IGM usually occurs in young women with a history of breastfeeding. In the absence of appropriate treatment, it becomes chronic with a high risk of recurrence.
Although the etiology of IGM remains unclear, it is generally considered to be idiopathic, although some etiologic causes have been suggested. These include immune system response, foreign body reaction, an unidentified infectious agent, smoking, α1-antitrypsin deficiency, breast trauma, and racial characteristics. The fact that it accompanies conditions such as pregnancy, lactation period, galactorrhea with high prolactin level, and oral contraceptive use suggests that a hormonal irregularity may also contribute.^3,4,5 The main mechanisms in etiology include hypersensitivity to extravasated lactational product, local breast trauma, subclinical infection, and autoimmune conditions.⁶
Definitive diagnosis is based on histological examination of excisional biopsy specimens. Histopathologically, granuloma formation is often noted. IGM is characterized by the presence of epithelioid and multinucleated giant cell granulomas. Diagnosis is made only after exclusion of infective causes such as inflammatory breast carcinoma, tuberculosis, parasitic and fungal infections, and non-infective causes such as sarcoidosis, Wegener’s granulomatosis, giant cell arteritis, polyarteritis nodosum, and foreign body reaction.⁶ As the etiology of IGM, the treatment method is still controversial. Therapeutic options range from observation to various medical treatments such as steroids, immunosuppressants, and antibiotics, and surgical intervention, especially if secondarily infected.^7,8 Although the disease can be locally aggressive, recurrence rates (16-50%) are still high after treatment.² Therefore, surgical management and follow-up of the disease are essential.
In this study, we discussed the clinicopathological features and surgical experience of patients treated with the diagnosis of IGM in our clinic in light of current literature.

Materials and Methods

In this retrospective study, 45 female patients over the age of 18 who were treated with the diagnosis of IGM at Ankara University Surgical Oncology Clinic between January 2012 and December 2020 were included. Demographic information and clinicopathological features of 36 patients who were followed up were recorded from hospital electronic records. The diagnosis of IGM was confirmed histopathologically from biopsy specimens. All pathology preparations were stained with special dyes such as hematoxylin-eosin, Ziehl-Neelsen (for tuberculosis), and periodic acid-Schiff (for fungal infection).
Our study protocol was reviewed and approved by the medical faculty ethics committee (Decision no: İ2-124-21).
Antibiotic treatment was administered to patients with microabscesses, which allowed them to shrink or merge into a single abscess. In patients whose abscesses developed into a single large abscess, the abscess was excised and drained, followed by extended resection after contraction of the lesion.
Statistical analysis was performed using SPSS version 24.0 by the biomedical informatics team. Descriptive analyzes of all data were performed, and data were presented as mean ± standard deviation (SD) values. Comparisons between categorical variables were made using Pearson’s χ2 test or Fisher’s exact test. A p-value of < 0.05 was considered statistically significant.

Results

Patient demographic and clinical variables are shown in Table 1.
The clinical appearance simulated malignity in half of the patients (n=18, 50%) at the diagnosis stage. Twenty (55%) patients were treated with antibiotics before referring to our clinic. Fistula formation was present in 15 (42) patients. A significant correlation was found between the probability of IGM and retro-areolar/central localization (p=0.001).
The characteristics of the diagnoses and treatment of IGM patients are shown in Table 2.
The radiological features of the patients are shown in Table 3 .
In the radiological evaluation: Parenchymal mixed echogenicity, focal asymmetric density, and mass enhancement were the most common findings on ultrasound, mammography and MRI, respectively.
In 24 patients (67%), core breast mass biopsy was performed and IGM was diagnosed in 16 patients. In other patients, tissue diagnosis was made by incisional biopsy performed during abscess drainage.
Thirty two (88%) patients underwent a surgical procedure. In 18 (50%) patients, breast mass excision with lumpectomy was performed, breast abscess drainage was performed in 12 (33%) patients, and 2 (5%) patients underwent a wide excision of the breast mass.
Oral prednisolone treatment, which was initiated before surgery, was continued for 4 weeks in 4 patients.
The mean follow-up period was 9 months (range 5-36). Recurrence developed in 9 (25%) patients. A recurrent breast mass developed in the same location at a mean of 8 (1-25) months after abscess drainage (n = 4) and lumpectomy (n = 3) in 7 patients, and fistula developed in 2 patients at 7 and 22 months after abscess drainage. All patients underwent a wide excision for recurrent breast mass and fistula. Patients were administered 20 mg oral prednisolone treatment daily for 2 weeks after excision. Three of the patients who developed recurrence (8%) had recurrence after 7.1 and 37 months. All three patients underwent re-excision for breast lesions.

Discussion

The mean age at onset of IGM is 34 years, which mimics breast cancer both clinically and mammographically.⁶ More than half of the cases reported in the literature are confused with breast cancer at the time of diagnosis. Therefore, it may cause unnecessary mastectomy.^9,10 Especially in young patients, the application of mastectomy based on triple evaluation (clinical, mammographic, and FNAC) is not considered a correct approach. Absolute accuracy of pathological diagnosis should be confirmed with frozen sections before performing mastectomy or breast-conserving surgery. The mean age of the patients in our study was 36 years. Similarly, since we experienced this dilemma in half of the patients, advanced surgical techniques were not used before the histopathological results of all patients were finalized. When necessary, the diagnosis was reinforced with frozen sections. Then, operations were planned for the diagnosis of IGM. Only two-thirds of patients who underwent core needle biopsy had a true histopathological diagnosis.
None of our patients were using oral contraceptives. Although various rates of oral contraceptive use are reported in the literature, there also are reports stating that there is no use.^6,10 All of our patients had unilateral involvement with right breast predominance (58%). Although the lesions are mostly centrally located, they have also been reported in all localizations. IGM is usually unilateral and can affect any quadrant of the breast.¹⁰ Our analysis determined that IGM was associated with the retroareolar/central localization of the main ducts. This likely supports the immune response secondary to ductal injury. Besides, smoking and fluctuations in prolactin levels during lactation are also blamed in the etiology. Smoking rate was 14%, and the rate of lactating women was 25% in the patients included in our study.
IGM diagnosis is exclusion and should be considered when all known infectious and non-infectious causes of granulomatous inflammation have been excluded.¹¹ Bacterial cultures of the lesions and positive serology may help make the diagnosis. In our study, we excluded infectious causes with the serological examinations requested at the diagnosis stage. A clinically painful, palpable mass-like lesion is the most common physical finding.⁴ The painful mass presentation rate was 69% in the patients included in our study. One-third of the patients were admitted with typical abscess symptomatology.
On ultrasound, hypoechoic tubular lesions in the breast tissue and/or the presence of a large mixed echogenicity suggest a diagnosis of IGM. In our study, these ultrasound findings were present in 83% of the patients. Along with this pattern, the presence of a focal asymmetric density on mammography further strengthens the diagnosis.³
However, for some patients, confirmation of the diagnosis by dynamic contrast MRI may be required.¹² We needed to confirm the diagnosis with MRI in 14% of the patients included in our study. Especially thanks to its cross-sectional imaging feature, it can clearly reveal fistula tracts.¹³ As a matter of fact, two of our patients who developed fistula were evaluated with MRI, and the extensions of the fistula tracts to the breast parenchyma were determined.
There is no ideal treatment for IGM; a meta-analysis report indicated no significant difference in recurrence rate between conservative treatment and surgical treatment.¹⁴ However, most surgeons, including our clinic, still adopt wide local excision with or without steroid therapy.^15,16 Thus, there is hope for a cure for this disease with a persistent mass or a strong propensity for recurrence.¹⁷ To minimize the side effects of steroid therapy and avoid surgery, some clinics focus on topical steroids and local injection.^8,18,19 However, our policy regarding steroids is limited to the continuation of treatment started only in recurrent cases or at the time of admission to our clinic.
Interestingly, 50% of patients relapse despite all treatments, and therefore, long-term close follow-up is required. Many authors still advocate complete resection whenever possible, given the difficulty of differential diagnosis from breast cancer.¹⁷ It has also been reported that the most important factor in the prevention of IGM recurrence is early diagnosis.²⁰ The recurrence rate in our study was 25%. All recurrences were managed with surgical excision and corticosteroid therapy. In one-third of the patients who developed recurrence, the management of relapses was provided by re-excision..

Limitations

Our study has limitations as it is retrospective. Only patients who underwent surgery were included in the study. Those who received conservative treatment were excluded from the study.

Conclusion

IGM clinically and histologically mimics an inflammatory carcinoma. An accurate approach that includes ultrasound, clinical and histological analysis can reliably identify a patient with this pathology. Our study supports secondary immune response in etiology.

Declarations

References

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About This Article

Received:

July 16, 2022

Accepted:

October 8, 2022

Published Online:

January 12, 2023

Printed:

February 1, 2023