Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) commonly metastasizes to cervical lymph nodes, liver, lungs and bone. Metastatic lesions in the breast have been previously reported but they are extremely rare and to our knowledge, this is the first case in literature described on a male patient. We report a case of a 49-year-old man with a 23-year history of sporadic MTC with bone, liver and lung metastases treated with somatostatin analogues for 6 years, who developed a painful breast metastasis.

Case report: A 49 year-old man was diagnosed in 1985 of a MTC. Total thyroidectomy was performed and from then onwards he has been followed up in our hospital for this purpose. In 1992 he received external radiotherapy for a neck mass. In 1994 he presented bone and lung metastases. In 2002 as Calcitonin levels increased (55 000 pg/ml) he started with incoercible diarrhea. Treatment with Lanreotide was initiated and a marked control of the diarrhea was achieved. Since 2004, when liver metastases appeared, he has had a stable control of the disease, until last year, when he presented painful bilateral gynecomastia and a 1 cm left breast mass on ultrasonography. Fine needle aspiration biopsy revealed a metastatic MCT. Although his disease was widely spread, because of the pain, he underwent left mastectomy. The pathologic examination of the specimen revealed metastatic MTC with positive immunologic staining for Calcitonin.

Conclusions: (1) This case illustrates a rare site for thyroid metastases and differs form other cases reported, in the patients gender. Breast metastases should be considered a diagnostic possibility in patients with MTC presenting with breast lesions.

(2) Cytological features and a positive immunocytochemistry for Calcitonin can be useful to confirm the diagnosis of metastatic MTC.

(3) Somatostatin analogues have played an important role on controlling the diarrhea and the course of our patient’s disease.