Parafollicular C-cell hyperplasia. Report of three cases in primary thyroid lymphomas.

Three cases of C-cell hyperplasia were observed in a series of 21 cases of primary thyroid lymphoma (PTL). The association is not well understood, since PTL is not included in the group of thyroid diseases which are known to cause C-cell hyperplasia. It may be interpreted as a compensatory reaction to diffuse and rapid destruction of most of the gland, or a "stimulation" related to the production of "bio-humoral" factors by neoplastic cells.