Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) originated from parafollicular C cells of the thyroid gland is a rare histological type of malignancy. Common sites of metastases are liver, lungs and bones, while metastases in other sites are extremely rare. Breast metastases from MTC are reported in 20 cases, and only in women.

Case report: A 67-year-old man was presented after thyroidectomy for further evaluation and treatment. Histology was positive for MTC with extrathyroidal extension and bilateral cervical lymph node metastases. Postoperative calcitonin was 613.6 pg/ml (normal range <10 pg/ml) and RET protooncogene was found negative for multiple endocrine neoplasia. Computed tomography and bone scan revealed metastases to lung and bone. Administration of tyrosine kinase inhibitor (vandetanib) was decided which was soon stopped due to serious adverse events (thrombocytopenia, bleeding, and impaired renal function). Antimotility agents and somatostatin analogues (octreotide LAR 20 mg) were used to control diarrhea. Seven months later he presented a painful swelling of right breast. Breast ultrasound revealed the presence of multiple, solid masses in the right breast and mammography was suspicious of malignancy. Core needle biopsy was positive for metastases from the known MTC. Palliative external beam irradiation was decided with mild relief of pain. The patient succumbed 1 month later. A literature search was conducted. No other cases of breast metastases from MTC in men were found.

Conclusion: This is the first reported case of breast metastasis from MTC in men. Breast masses in the course of MTC should be evaluated for metastases since the therapeutic approach is different from that of primary breast carcinoma. Palliative external radiation therapy should be considered for metastatic and lesion causing pain.