Sporadic medullary thyroid carcinoma associated with toxic multinodular goitre.

First described in 1959, medullary thyroid carcinoma (MTC) arises from parafollicular C cells distributed throughout the thyroid, and may occur in one of two clinical forms, sporadic (80%) or familial. Familial MTC may present as a palpable thyroid nodule, but may also be diagnosed by screening relatives of an index case for a raised basal serum calcitonin or a rise in calcitonin following a stimulated pentagastric test. Both tests are highly sensitive for C-cell hyperplasia and MTC. Sporadic cases of MTC most commonly present as asymptomatic thyroid nodules with normal thyroid function tests. In this note, the history of a patient is presented in which a sporadic MTC was associated with goitre and both symptoms and biochemical evidence of thyrotoxicosis.