Thyroid c cells in the digeorge anomaly: A quantitative study

The developmental field defect in the DiGeorge anomaly (DGA) principally affects derivatives of the third and fourth branchial pouches (areas containing a large population of cephalic neural crest cells), including the ultimobranchial body (UB), the reputed source of thyroid calcitonin-producing cells (C cells) in humans. To evaluate the content of C cells in children with DGA, sections of the thyroid in 16 cases of DGA (group I) (8 incomplete and 8 complete forms) and 16 age-matched controls (group II) were stained by immunoperoxidase for calcitonin and chromogranin. Eleven of 16 (69% cases in group I [4 of 8 (50% of the complete and 7 of 8 (88% of the incomplete cases] and 14 of 16 (88% of group II exhibited positive-staining cells for both markers, either individually or in small clusters within the follicular epithelial basement membrane. The average number of C cells per high-power field (HPF) (400 x) for group I was 1.6 ± 0.9 and for group II 4.9 ± 1.7 (P < 005). Although the percentage of positive incomplete DGA cases was the same as that of the control cases, the average number of C cells/HPF was 2.0 ± 1.1 and similar to that of complete DGA cases (1.2 ± 0.6). These results demonstrated that C cells are present in the thyroid of patients with DGA more frequently than expected, although in deficient numbers when compared quantitatively to age-matched controls showing a normal infantile pattern of thyroid C cell distribution. Although this observation confirms that there is deficiency of thyroid C cell development in DGA and is in keeping with the assumption that the cells are of neural crest origin, our data raise the possibility of an additional source of C cells, perhaps from thyroid endoderm, in a manner analogous to the endocrine cells of the gut and respiratory tract..