Sex-related C cell hyperplasia in the normal human thyroid: a quantitative autopsy study

We report a prospective quantitative image analysis study of C cells in 57 normal autopsy thyroid glands, serially sectioned and wholly embedded in paraffin; all slides were immunohistochemically stained for calcitonin. Computerized quantitative image analysis was performed on 47 cases to measure C cell surface area and parenchymatous surface area after immunoperoxidase staining for calcitonin. The method was time-effective, with a good reproducibility. C cells were mainly found in the middle third of each lobe. Important inter-individual variations were observed; the maximum C cell surface area in a section (Amax) ranged from 28 x 10(3) to 470 x 10(3) microns2 (mean, 167 x 10(3) microns2) among 42 adults. Of particular interest was the important difference observed between sexes; Amax was twice as high in men (mean, 201 x 10(3) microns2) as in women (mean, 91 x 10(3) microns2; P = 0.0009). Moreover, 14 (33%) adult subjects [2 women (15%) and 12 men (41%)] fulfilled C cell hyperplasia criteria, i.e. at least 3 fields at x 100 magnification containing more than 50 C cells, suggesting that a substantial part of the normal adult population could have C cell hyperplasia.