Histology Course S X 8 Department of Pathology, University of Zurich Histology Course

S X 8 undifferentiated thyroid carcinoma  HE  
  ICD-10: C73.9; ICD-O: 8020/3

74-year-old male, goitre for many years; a mobile palpable nodule on the hand side for many years; no increase in size. The nodule started growing 2 months ago and has now become fixed; the patient has developed difficulty breathing and a hoarse voice.

Fine needle biopsy: cells of a poorly differentiated polymorphous tumour.
Partial thyroidectomy: The thyroid gland is difficult to separate from the trachea since the recurrent laryngeal nerve is surrounded by the thyroid.
Macroscopically: the cut surface appears grey, with a partly haemorrhagic node, the capsule is partially destroyed.

- Remaining thyroid tissue (only seen on some specimen)
- Solid, partially necrotic tumour with infiltrative, destructive growth
- Invasion into striated muscle
- No recognisable follicles or papilla
- High-grade cell and nuclear polymorphism, sarcomatous aspect
- Numerous, partly atypical mitoses
Many undifferentiated thyroid carcinomas develop from follicular carcinoma. The prognosis is poor.