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Updated: Jul 27, 2026
An Orthotopic Mouse Model of Anaplastic Thyroid Carcinoma
Published on: April 17, 2013
Cytopathology of insular carcinoma of the thyroid
1Department of Laboratory Medicine and Pathology, University of Alberta Hospitals, Edmonton, Alberta, Canada. knguyen@cha.ab.ca
Insights
Fine-needle aspiration (FNA) of thyroid insular carcinoma (IC) shows abundant monomorphic cells. Definitive diagnosis of IC requires histologic examination of the excised tumor.
Area of Science:
- Endocrinology
- Oncology
- Cytopathology
Background:
- Thyroid carcinomas exhibit diverse cytomorphologic features.
- Insular carcinoma (IC) is a rare thyroid malignancy.
- Accurate preoperative diagnosis is crucial for patient management.
Purpose of the Study:
- To evaluate the cytologic findings of thyroid insular carcinoma (IC) on fine-needle aspiration (FNA).
- To determine the diagnostic accuracy of FNA for IC.
- To differentiate IC from other thyroid neoplasms.
Main Methods:
- Retrospective review of 5 thyroid tumors: 4 pure ICs and 1 IC with focal anaplastic carcinoma (AC).
- Cytologic evaluation of FNA samples.
- Histologic examination of excised tumors.
Main Results:
- FNA samples showed abundant monomorphic follicular cells in various arrangements (single, aggregates, clusters).
- Tumor cells had granular cytoplasm and oval nuclei with variable nucleoli.
- One case with focal AC showed large, pleomorphic malignant cells.
- No intact tumor cell nests (insulae) were identified in FNA specimens.
Conclusions:
- Thyroid IC may be suspected based on abundant cohesive and dyshesive monomorphic follicular cells in FNA.
- FNA findings can suggest IC, but a definitive diagnosis necessitates histologic examination of the excised tumor.
- Distinguishing IC from other follicular cell-derived thyroid tumors based solely on FNA can be challenging.
Abstract:
Four pure insular carcinomas (IC) and one IC with focal anaplastic carcinoma (AC) of the thyroid with cytologic evaluation by fine-needle aspiration (FNA) were reviewed. The needle aspirates from the four pure ICs revealed abundant monomorphic follicular cells present singly, in small, loose aggregates, and in cohesive trabecular and acinar clusters. Tumor cells showed fragile, ill-defined, granular cytoplasm and oval nuclei with conspicuous or inconspicuous nucleoli. The case of IC with focal AC yielded, in addition to the follicular cells as seen in the FNA of the 4 cases of pure IC, large pleomorphic malignant cells with prominent nucleoli that were characteristic for an AC, giant-cell type. No intact insulae of tumor cells were identified in any of the 5 cases. Thus, a thyroid IC may be suspected if abundant cohesive and dyshesive monomorphic follicular cells are present in the tumor FNA. However, a firm diagnosis of thyroid IC can only be made by histologic examination of the excised tumor.
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