Cholesterol granuloma consists of fibrous granulation tissue containing cholesterol crystals with foreign body giant cells. Cholesterol granuloma occurs commonly in the mastoid region and in various organs such as the peritoneum, kidney, parotid gland, thyroglossal duct, lymph node, liver, and spleen. However, cholesterol granuloma of the breast is a very rare tumor-like lesion and has been rarely reported. We herein report a rare case of cholesterol granuloma of the breast. Cholesterol granuloma should be considered in the differential diagnosis of breast lesion suspected to be malignant. [1] [2] [3] [4] [5] [6]

A 56-year-old Japanese asymptomatic female was admitted to our hospital with a diagnosis of sigmoid colon cancer. Computed tomography (CT) scan of her chest and abdomen was done as a preoperative examination of her colon cancer, and showed a nodule in the left breast. (Figure 1) The patient had no family history of breast cancer, no history of mammary trauma or biopsy and no history of lipid metabolism abnormality.

On admission, physical examination revealed a 2.0x2.0 cm palpable nodule which was elastically firm and mobile in the upper external quadrant of the left breast with no associated skin findings. There was no axillary or supraclavicular lymphadenopathy, and no abnormal nipple discharge. Mammography showed a 2.0 cm in diameter high-density shadow lesion, which corresponded to the palpable mass, with partly ill-defined margins and without specula or microcalcification. (Figure 2) An ultrasonography of the left breast revealed a hypoechoic and relatively irregularly shaped mass with an ill-defined margin. (Figure 3) A core needle biopsy of the lesion showed fibrosis and a small granulomatous lesion infiltrated by lymphocytes and foamy histiocytes, and there was no evidence of malignancy. From the physical examination, CT scan, ultrasonographic findings, a diagnosis of breast cancer could not be ruled out, and an excisional biopsy was also done when the sigmoidectomy was performed.

The surgical specimen measured 2.4 cm in diameter and was a cystic and firm mass. The histological evaluation revealed a cystic mass surrounded by fibrous granulation tissue in which needle-like crystals were deposited and accompanied by giant cells. (Figure 4) These findings were compatible with cholesterol granuloma. Our follow-up, the patient was remained uneventful since 60 months.

We herein report a rare case of cholesterol granuloma of the breast. Cholesterol granuloma of the breast is composed of fibrous granulation tissue in which cholesterol crystals accompanied by giant cells are deposited. The pathogenesis of cholesterol granuloma is not fully understood. Physical and infectious factors have been considered and some reports postulate that they are caused by a reactive response to an unknown stimulus. In the breast, cholesterol granuloma is thought to represent a rare manifestation of duct ectasia. Lipid-rich material is normally found in ectatic ducts. It is postulated that leakage of cholesterol crystals from the ectatic ducts causes a foreign body giant cell reaction which results in granuloma formation. Mammary duct ectasia is a disorder of middle-aged women. Mammary duct ectasia is a frequent disorder of the breast that has a wide variety of clinical manifestations, and this disorder sometimes involves an extensive disruption of the dilated duct and is occasionally noticed as a palpable mass. In rare instances the mass, microscopically, contains cholesterol crystals. In the pathologic specimen in this case, a cystic lesion surrounded by fibrous granulation tissue, chronic inflammation, cholesterol crystals, and scattered multinucleated giant cells was observed. The lesion was considered to be cholesterol granuloma associated with duct ectasia. [1] [2] [3] [4] [5] [6]

The main concern with breast cholesterol granuloma is performing differential diagnosis. Clinically, it resembles breast cancer. The clinical and radiological features of cholesterol granuloma mimic those of a carcinoma of the breast. Thus, it is difficult to distinguish cholesterol granuloma from carcinoma of the breast based on the imaging results. The diagnosis of cholesterol granuloma is histologic. It is not difficult to distinguish between cholesterol granuloma and breast cancer histologically, and core needle biopsy is thought to be useful for differential diagnosis. However, it should be noted that breast cholesterol granuloma could be accompanied by cancer. Thus, cases in which malignancy cannot be ruled out clinically, a complete removal of the tumor helps in making a definitive diagnosis. [1] [2] [3] [4] [5] [6]

We here reported a rare case of breast cholesterol granuloma mimicking breast cancer. Reports on breast granuloma are rare. However, duct ectasia itself, which is related with cholesterol granuloma, is a very frequent disorder. To make an accurate diagnosis of this rare disorder and rule out the possibility of cancer, a histological examination is required.

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