Hormone receptor-positive male breast cancer: spontaneous regression after biopsy and mastectomy

What happened, in summary

A 58-year-old man came to a surgical clinic with a palpable lump behind the left nipple, nipple retraction, and intermittent pain for 2 months. Ultrasound showed a solid retroareolar lesion, and biopsy confirmed invasive breast carcinoma that was estrogen receptor-positive, progesterone receptor-positive, and HER2-negative, at least grade 2. Staging CT showed a 2.2 cm left breast lesion with no clear liver, kidney, abdominal, pelvic, bone, mediastinal, or hilar spread. A lung nodule initially raised concern, but comparison with later PET-CT showed it had disappeared, supporting infection rather than metastasis. The prostate was enlarged and FDG-avid, so urology evaluation was arranged separately. A multidisciplinary team recommended upfront surgery because there was no confirmed metastatic disease and the cancer was hormone receptor-positive. About 3 months later, he underwent left mastectomy with axillary clearance. During surgery, no breast mass was felt, although multiple enlarged axillary nodes were removed. Microscopic examination of the breast and 25 lymph nodes showed no residual invasive carcinoma and no carcinoma in situ. Instead, the specimen contained a benign cystic lesion with hemorrhagic or regressive changes, scar-like fibrosis, chronic inflammation, and benign breast tissue. Margins were clear, and the pathologist reported spontaneous regression of the tumor. He recovered well and started tamoxifen 20 mg once daily because the original biopsy had proven ER/PR-positive invasive disease. Follow-up continued every 3 months with breast ultrasound, while the prostate finding was managed by urology. His other medical conditions included ischemic heart disease, dyslipidemia, and type 2 diabetes, all controlled with oral medication, which made a coordinated surgical plan especially important.