Non-functional C-cell adenoma in aged horses.

The research investigates thyroid tumours in older horses, suggesting that they are primarily derived from parafollicular cells, or C cells. These tumours, termed C-cell adenomas, are non-functional and do not appear to contribute to diseases related to calcitonin overproduction.

Investigation Approach

• The researchers examined thyroid glands from 38 horses between the ages of 10 and 29 years.
• All tissue samples were studied in three ways: histologically (looking microscopic tissues), immunohistochemically (identifying cells in tissues), and ultrastructurally (observing the structure within the cells).

Findings

• The team discovered nodular tumour masses in the thyroid glands of 12 out of 38 horses older than 10 years (31.6%) and in nine of 12 horses older than 20 years (75.0%). This observation had no connection with the sex or breed of the horses.
• The nodules were made up of solid proliferations of polygonal cells with eosinophilic (acid-loving), granular cytoplasm.
• Immunohistochemical analysis showed that the tumour cells tested positive for calcitonin and neuron-specific enolase, but not for thyroglobulin (a protein produced and used by the thyroid gland).
• Upon ultrastructural examination, they found very few (if any) secretion granules within the tumour cells.

Conclusions

• Considering these results, the research team concluded that the nodular lesions in question were C-cell adenomas, not follicular adenomas as previously thought.
• They suspected that the C-cell adenomas were non-functional i.e., they did not actively secrete hormones or cause a functional imbalance, leading them to believe that these adenomas are unlikely to cause diseases related to the overproduction of calcitonin.