Symptomatic C-cell hyperplasia associated with chronic lymphocytic thyroiditis.

A 58-year-old euthyroid man with episodic flushing and a 2-year history of progressive wheezing was found to have a hypoechoic lesion in one lobe of his thyroid and hypercalcitoninemia in response to pentagastrin stimulation. Thyroidectomy revealed bilateral C-cell hyperplasia unexpectedly associated with chronic lymphocytic thyroiditis. The C-cells exhibited positive immunohistochemical staining for calcitonin and polyclonal carcinoembryonic antigen (CEA). Postoperatively, the wheezing and flushing subsided and the serum calcitonin level was not elevated with pentagastrin stimulation. The substance or substances responsible for the wheezing and flushing were not specifically identified. Nine other specimens of chronic lymphocytic thyroiditis were examined for C-cell hyperplasia and two had small hyperplastic foci, but of a lesser degree than the index case. These patients did not exhibit wheezing and flushing. The development of C-cell hyperplasia in chronic lymphocytic thyroiditis is uncommon and the mechanism for its occurrence is unexplained. This patient appears to be the first reported case of symptomatic C-cell hyperplasia associated with chronic lymphocytic thyroiditis. The substance or substances responsible for the clinical symptoms remain to be identified.