Thyroid Gland - C Cell Hyperplasia

Image of C cell hyperplasia in the thyroid gland from a female F344/N rat in a chronic study
Thyroid gland, C cell - Hyperplasia in a treated female F344 rat from a chronic study. Aggregates and small nests of C cells have replaced follicles in this thyroid gland.
Figure 1 of 4
Image of C cell hyperplasia in the thyroid gland from a female F344/N rat in a chronic study
Thyroid gland, C cell - Hyperplasia in a treated female F344 rat from a chronic study. Higher magnification of Figure 1 shows the contiguous nests of C cells surrounding small follicles.
Figure 2 of 4
Image of C cell hyperplasia in the thyroid gland from a male F344/N rat in a chronic study
Thyroid gland, C cell - Hyperplasia in a control male F344 rat from a chronic study. A focal proliferation of C cells is present in this thyroid gland (arrow).
Figure 3 of 4
Image of C cell hyperplasia in the thyroid gland from a male F344/N rat in a chronic study
Thyroid gland, C cell - Hyperplasia in a control male F344 rat from a chronic study. Higher magnification of Figure 3 shows illustrates the high nuclear-to-cytoplasmic ratio in this focal proliferation of C cells.
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comment:

C-cell hyperplasia is a common finding in chronic rat studies and can be diffuse ( Figure 1image opens in a pop-up window and Figure 2image opens in a pop-up window ), focal ( Figure 3image opens in a pop-up window and Figure 4image opens in a pop-up window ), or multifocal. C-cell hyperplasia is distinguished from C-cell adenoma based on the size of any given focal proliferation. The generally accepted criteria for C-cell hyperplasia is a focal C-cell cluster less than five average follicular diameters or similarly small-sized clusters of C cells scattered in interfollicular spaces. In contrast to C-cell adenomas, C-cell hyperplasia is not associated with significant compression of adjacent parenchyma. C-cell hyperplasias may contain individual trapped follicles ( Figure 1image opens in a pop-up window and Figure 2image opens in a pop-up window ). C-cell hyperplasia generally consists of round to polyhedral cells with abundant eosinophilic cytoplasm ( Figure 2image opens in a pop-up window ); in some cases there is a higher than typical nuclear-to-cytoplasmic ratio ( Figure 4image opens in a pop-up window ).

recommendation:

C-cell hyperplasia should be diagnosed when present, given a severity grade. If bilateral it should be indicated in the diagnosis with a severity grade based on the more severely affected thyroid gland.

references:

Capen CC, Martin SL. 1989. The effects of xenobiotics on the structure and function of thyroid follicular and C-cells. Toxicol Pathol 17:266-293.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/2675279

Capen CC, DeLellis RA, Yarrington JT. 2002. Endocrine system. In: Handbook of Toxicologic Pathology, Vol 2 (Haschek WM, Rousseaux CG, Wallig MA, eds). Academic Press, New York, 681–783.
Abstract: http://www.sciencedirect.com/science/book/9780123302151

Chandra S, Hoenerhoff MJ, Peterson R. 2013. Endocrine glands. In: Toxicologic Pathology: Nonclinical Safety Assessment (Sahota PS, Popp JA, Hardisty JF, Gopinath G, eds). CRC Press, Boca Raton, FL, 655-716.
Abstract: http://www.crcpress.com/product/isbn/9781439872109

Collins WT, Capen CC, Kasza L, Carter C, Dailey RE. 1977. Effect of polychlorinated biphenyl (PCB) on the thyroid gland of rats. Ultrastructural and biochemical investigations. Am J Pathol 89:119-136.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/199066

Greaves P. 2007. Histopathology of Preclinical Toxicity Studies: Interpretation and Relevance in Drug Safety Evaluation, 3rd ed. Academic Press, Amsterdam, 819-839.
Abstract: http://www.sciencedirect.com/science/book/9780444527714

Hardisty JF, Boorman GA. 1990. Thyroid gland. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 519–536.
Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563