Simultaneous medullary carcinoma, occult papillary carcinoma and lymphocytic thyroiditis

A 55-year-old female underwent total thyroidectomy for medullary carcinoma of the left lobe of the thyroid. The right lobe showed an incidental occult papillary carcinoma. There was also diffuse lymphocytic thyroiditis. Immunohistochemistry for calcitonin and thyroglobin confirmed the separate histogenesis for both carcinomas. The coexistence of medullarry and papillary carcinoma of the thyroid is rare and the literature usually documents mixed tumours with features of both carcinomas, rather than independent tumours, as in our case.