Cytogenetic tetraclonality in a rare spindle cell variant of an anaplastic carcinoma of the thyroid.

We report a case of an unusual anaplastic carcinoma with spindle cell differentiation in an 85-year-old patient. Although the tumor showed sarcoma-like features its occurrence in the thyroid of an elderly person supported the diagnosis of an anaplastic carcinoma. This diagnosis is also supported by the results of cytogenetic studies that revealed four independent clones. Of these, three clones showed complex chromosomal rearrangements including translocations, deletions and inversions while the remaining clone only showed two balanced translocations. The patient is still alive after 13 months.