Case history:
A 63-year-old male patient with history of chemotherapy for follicular lymphoma presented with a left breast mass detected on a periodic computed tomography (CT) scan. He was diagnosed with follicular lymphoma five years ago and treated with six cycles of a combination of rituximab and bendamustine, followed by treatment with rituximab for two years as maintenance therapy. Recurrence of lymphoma was detected at the cervical and axillary lymph nodes after two years of an uneventful post-therapeutic course. Lenalidomide and rituximab were administered as treatment for recurrence. A CT scan performed at the end of chemotherapy showed disappearance of all target lesions, but appearance of a new mass in his left breast. The patient was referred to our department for further evaluation. On physical examination, a mass measuring approximately 1 cm in diameter was palpable in the subareolar area of his left breast, while no swollen lymph nodes were detected in the ipsilateral axillary region. Laboratory tests including tumor marker analyses were all within normal levels (white blood cell, 2840 /µl; C-reactive protein, 0.032 mg/dl; carcinoembryonic antigen, 3.8 ng/ml; cancer antigen 15-3, 17 U/ml; sIL-2R, 385 U/ml). CT scan confirmed the presence of a lesion measuring 13.9 × 12.9 × 6.1 mm in the subareolar portion of the left breast (Fig. 1). Breast ultrasonography revealed an ill-defined hypoechoic irregular mass with peripheral vascularity in the subareolar portion (Fig. 2). Ultrasound-guided core needle biopsy was performed, and histological examination showed a granulomatous structure comprising mononuclear inflammatory cell infiltration accompanied by foam cells without any evidence of caseous necrosis (Fig. 3). No specific pathogen or foreign bodies were detected. These findings confirmed the diagnosis of GM.
Since there was no suspicion of malignancy and the patient was asymptomatic, he was admitted for observation. Ultrasonography performed after three months revealed that the size of the tumor was 7.9 × 5.5 × 5.2 mm (Fig. 4), which was smaller compared to the initial diagnosis. The patient is currently under observation.