40-year-old female, surgery due to a solitary thyroid nodule left, cold node, chronic diarrhoea for several months, plasma CEA (carcino-embryonic- antigen): 365 ug/l (N:0-5), serum calcitonin:850 pmol /l (N:<29;8-55)
- Extensive destruction of thyroid parenchyma by partly cell-poor, partly cell-rich nodular tumour tissue.
- Infiltrative destructive growth, poorly demarcated, invasion of vessels.
- The tumour cells are arranged in groups/plates/strands, and are partly spindle-cell-shaped with an elongated nucleus.
- Moderate to extensive cell and nuclear polymorphism
- Several mitoses
- The cell-poor areas contain cloudy masses with a varying degree of eosinophilic stains (amyloid)
- The amyloid consists here of por-calcitonin (and possibly amylin as in insulinoma)
Comment: The medullary thyroid carcinoma can be associated with multiple endocrine neoplasia (MEN) 2a or 2b.