Definition
The is a high grade malignancy arising by dedifferentiation of a pre-existing papillary or follicular carcinoma. The dedifferentiation may occur within the primary tumour of may be found only in a metastasis4, sometimes years after the primary thyroid carcinoma has been treated.
The anaplastic component usually dominates, but sometimes may be a minor component of the tumours. The anaplastic tumour itself comprises a variable proportion of spindle, polyhedral and multinucleate giant cells. There may be foci of squamous differentiation, of osteoclast-like giant cells or corresponding mononuclear cells, foci resembling angiosarcoma or foci of osteoid.
The mononuclear polyhedral cells may contain rhabdoid eccentric hyaline inclusions, displacing the cell nuclei. [The inclusions are similar to those that have been reported in poorly differentiated follicular carcinoma of the thyroid2.]
The differentiated component may be papillary carcinoma (conventional, tall cell or follicular variants), follicular carcinoma or oncocytic carcinoma. Some cases arise against a background of adenomatous goitre or in the absence of thyroid pathology
|
11/111, 1/13 |
|||
|
Cytokeratin |
7/111, 1/13 |
||
|
0/111, 0/13 |
|||
|
0/13 |
|||
|
0/111 |
|||
|
1/13 |
|||
|
Sarcomeric actin |
1/13 |
||
|
0/13 |
|||
|
0/13 |
|||
The rhabdoid inclusions consist of paranuclear whorls of intermediate filaments. [They differ from thyroglobulin inclusion which are filled with granular electron-dense material.]
Molecular genetics
In come cases, RET/PTC rearrangements argue for origin from a papillary carcinoma3.
This is a high grade malignancy with a high mortality.
This page last revised 3.6.2007.
©SMUHT/PW Bishop