Discussion:
GM is diagnosed histologically by confirming the presence of non-necrotizing granuloma formation, without any evidence of microorganisms such as Mycobacterium or fungi.2 Its etiology is uncertain, and imaging findings are not specific. GM occurs in female breasts and accounts for 1.8% of benign breast disorders proven by biopsy.3 It mainly affects females of reproductive age. The mean age at presentation is 33–38 years.1,4,5 Hormonal disruption and autoimmune responses have been suggested as the possible etiological factors.6
GM is rarely observed in males. To the best of our knowledge, there are only 16 reported cases of GM in male patients.1,2,4-15The reported cases have been summarized in Table 1. We analyzed 12 cases of patients whose characteristics and clinical courses were described.2,6-15 The median age of the patients at the time of presentation was 46 years (range: 17–60 years). Eight patients (73%) had GM in the right breast, while two (17%) presented with bilateral involvement. The median size of the masses was 20 mm (range: 5–72 mm). All patients had a breast mass with or without pain, while two (17%) had ulcerations. Nipple discharge was observed in only one patient (8%). A definitive diagnosis of GM was obtained by core needle biopsy in eight patients (67%), by fine needle aspiration in one patient (8%), and by excisional biopsy in three patients (25%). The baseline characteristics of female GM patients have been described as follows: mean age of 36 years, lesion measuring approximately 50 mm, and nipple discharge observed in 30% patients.16
One possible reason for rarity in males is the absence of mammary lobules, which are usually affected during this disease. It has been reported that estrogen stimulation causes the development of acini and lobules in male breasts2 and might be responsible for the development of GM. Of the 12 cases, four patients had gynecomastia10,14,15,16 and one was a transgender (male to female transition, receiving estrogen therapy for six years).2 This supports the fact that GM in males might be associated with abnormal hormonal conditions such as gynecomastia and estrogen therapy. This may also be responsible for the higher age of affected male patients compared to female patients, since the ratio of androgen to estrogen in males lowers with age.18However, hormonal involvement was not detected in the remaining seven cases and our case. Therefore, it can be concluded that the etiology of GM in males remains unclear.
The optimal treatment strategy for GM remains controversial. Treatment approaches include observation, oral corticosteroid administration, and surgical excision. Incision and drainage may be a treatment option for bacterial infection cases. Oral corticosteroids have been used as the first-line treatment in some studies and reported to be effective in decreasing the size of GM.4 However, observation without any therapeutic intervention could be considered for asymptomatic cases. Some studies have reported that GM patients who underwent observation without any medication achieved resolution in 7–14.5 months.19,20
Of the 11 reported male cases in which treatment was mentioned, four patients underwent surgical excision. Core needle biopsy was not attempted in these four cases, and the lesion was surgically excised in toto as an excisional biopsy. Of the remaining seven patients, four who received oral corticosteroid therapy were symptomatic, whereas two who underwent observation did not have any symptoms other than the breast mass. In one patient who was treated with bromocriptine for pituitary tumor, the breast tumor disappeared after the treatment. None of the patients experienced recurrence during their clinical course, but the follow-up periods were not sufficient to determine the long-term outcomes. In our case, since the patient was asymptomatic and diagnosis of GM was confirmed histologically, we decided to observe the lesion.
In contrast to other reported cases, the tumor in our case appeared during the clinical course of follicular lymphoma treatment. Although not histologically proven, one possible explanation for the occurrence of GM in our case may be the autoimmune response toward the extranodal lesion of lymphoma in the breast.
To summarize, we presented a rare case of GM in a male patient. Observation may be a viable option in the asymptomatic cases. However, further studies including a larger number of patients and longer observation period are needed for reliable long-term outcomes.