Comparative immunohistochemical study of normal, hyperplastic and neoplastic C cells of the rat thyroid gland.
In rats, the frequency of spontaneous C-cell tumours is very high and is both age and gender dependent. The three specific stages of neoplastic progression can be distinguished into diffuse C-cell hyperplasia, focal C-cell hyperplasia and bona fide C-cell tumours. Based on this hypothetical model of human medullary thyroid carcinoma (MTC), we carried out an immunohistochemical study using different markers (calcitonin, calcitonin gene-related peptide, somatostatin and chromogranin) to verify the existence of any relationship between their expression and the successive steps of tumour development. We found a characteristic immunohistochemical staining pattern, particularly for calcitonin and somatostatin, which distinguishes C-cell tumours from both normal and hyperplastic C cells, with no differences related to the gender of the animals under study. Specifically, a considerable heterogeneity in calcitonin expression was only displayed by C-cell carcinomas, being less pronounced in C-cell adenomas. As for somatostatin, this regulatory peptide was found only in a minority of calcitonin-positive cells in normal and hyperplastic glands. However, in some C-cell adenomas and most C-cell carcinomas nearly all calcitonin-positive cells also coexpressed somatostatin. We conclude that rat C-cell neoplasms constitute a very particular tumour entity which shares many but not all immunohistochemical features with human MTC.
Departamento de Citología e Histología Normal y Patológica, Facultad de Medicina, Universidad de Sevilla, Av. Sánchez Pizjuan s/n., 41009 Seville, Spain. ilacave@us.es
I
I
Martín-Lacave
F
F
Rojas
R
R
Bernabé
J C
JC
Utrilla
J M
JM
Fernández-Santos
M
M
De Miguel
E
E
Conde
D000236:Adenoma / Q000473:pathology; D000818:Animals; D005260:Female; D006965:Hyperplasia; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D013961:Thyroid Gland / Q000166:cytology* / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology*