Related Experiment Videos
Poorly differentiated forms of papillary thyroid carcinoma: distinctive entities or morphological patterns?
S Pilotti1, P Collini, A Manzari
1Division of Anatomic Pathology and Cytology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milano, Italy.
Seminars in Diagnostic Pathology
|August 1, 1995
Summary
Poorly differentiated carcinomas (PDCs) in the thyroid gland, specifically papillary carcinoma-related PDCs (pPDCs), are distinct entities, not just variants. These pPDCs show a stronger correlation with adverse prognostic factors and higher recurrence rates than conventional papillary carcinomas (PCs).
Area of Science:
- Thyroid Pathology
- Surgical Oncology
- Endocrinology
Background:
- Poorly differentiated carcinomas (PDCs) are recognized as intermediate in the spectrum of follicular cell-derived thyroid carcinomas.
- Papillary carcinoma (PC) and follicular carcinoma (FC) represent distinct well-differentiated entities.
- The classification of papillary carcinoma-related PDCs (pPDCs) as a distinct entity versus a histologic variant requires further investigation.
Purpose of the Study:
- To determine if papillary carcinoma-related poorly differentiated carcinomas (pPDCs) are a distinct pathologic entity or a histologic variant of papillary carcinoma (PC).
- To evaluate the association between pPDC morphology and prognostic factors in thyroid cancer.
Main Methods:
- Reclassification of 227 consecutive papillary carcinomas (PCs) according to current World Health Organization (WHO) criteria.
- Statistical analysis using odds ratio to evaluate the association between pPDC patterns and prognostic factors (gender, age, pTNM).
- Comparison of clinicopathologic features between pPDCs and other PC variants.
Main Results:
- Of 227 PCs, 183 were classified as conventional variants (NOS, microcarcinoma, encapsulated, follicular) and 44 as pPDCs (tall cell, columnar cell, mixed).
- pPDC morphology showed significant correlation with age over 40, extrathyroidal extension, and lower nodal involvement.
- Tumoral pattern consistent with pPDC was the strongest predictor of biological behavior, with 5-fold higher recurrence and 20-fold higher recurrence-related deaths compared to conventional PCs.
Conclusions:
- Papillary carcinoma-related poorly differentiated carcinomas (pPDCs) represent a distinct pathologic entity, not merely a histologic variant of papillary carcinoma (PC).
- pPDC morphology is a significant predictor of aggressive tumor behavior, including increased recurrence rates and mortality.
- These findings highlight the importance of accurate classification for predicting prognosis in thyroid cancer patients.