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Co-existent anaplastic and well differentiated thyroid carcinomas: a nuclear DNA study
G Wallin1, M Bäckdahl, E Tallroth-Ekman
1Department of Surgery, Karolinska Hospital, Stockholm, Sweden.
Summary
Anaplastic thyroid carcinomas rarely arise from well-differentiated tumors. Most anaplastic thyroid cancers (ATCs) with co-existing differentiated components show aneuploid DNA, indicating a poor prognosis, suggesting de novo origin for most ATCs.
Area of Science:
- Oncology
- Pathology
- Genetics
Background:
- Anaplastic thyroid carcinoma (ATC) is an aggressive malignancy.
- The origin of ATC, particularly its relationship with well-differentiated thyroid carcinomas (WDTCs), remains incompletely understood.
- Clonal transformation of WDTCs is a proposed mechanism for ATC development.
Purpose of the Study:
- To investigate the incidence of WDTC foci within ATCs.
- To evaluate the ploidy status of co-existing anaplastic and well-differentiated tumor cells.
- To determine the potential role of clonal transformation in ATC pathogenesis.
Main Methods:
- Histological examination of 126 anaplastic (giant cell) carcinoma cases.
- Identification of well-differentiated tumor foci within or adjacent to anaplastic tumors.
- Cytophotometric DNA analysis (Feulgen staining) on 11 cases to assess ploidy.
Main Results:
- 13.5% of ATCs (17/126) contained foci of WDTCs, predominantly papillary.
- All 11 analyzed ATCs exhibited an aneuploid DNA pattern, correlating with poor prognosis (7/11 died within 6 months).
- Co-existing WDTCs were mostly diploid (6/7), with only one-third showing aneuploidy.
Conclusions:
- The co-existence of ATC and WDTC is rare.
- Aneuploidy in ATCs is common, while associated WDTCs are typically diploid.
- These findings suggest that most ATCs likely arise de novo rather than through clonal transformation of WDTCs.