Papillary and follicular thyroid carcinomas with an insular component

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• Papillary (PC) and follicular (FC) thyroid carcinomas can exhibit an insular component (IC).
• The prognostic significance of the extent of IC in these tumors remains unclear.

Purpose of the Study:

• To correlate the histologic behavior and extent of the insular component (IC) in papillary and follicular thyroid carcinomas.
• To evaluate the impact of IC on tumor stage, disease progression, and patient outcomes.

Main Methods:

• Review of 41 thyroid carcinomas with focal or predominant IC (17 follicular variants of PC, 24 FC).
• Histological analysis including nuclear features, vascular invasion, necrosis, and stroma.
• Immunohistochemical staining for carcinoembryonic antigen, thyroglobulin, and calcitonin.
• DNA ploidy analysis on 18 tumors.
• Correlation of IC extent with clinical data using Fisher's exact test.

Main Results:

• No tumor was purely insular; IC was minor in 16 and predominant in 25 cases.
• Vascular invasion, necrosis, and sclerotic stroma were common findings.
• Tumor stage varied, with regional spread in 13 and distant metastases in 9 cases.
• No correlation was found between the quantity of IC and tumor stage, follow-up status, or ploidy.

Conclusions:

• The presence and extent of an insular component (IC) within papillary and follicular thyroid carcinomas do not adversely affect prognosis.
• IC does not appear to be a significant independent prognostic factor in these thyroid cancer subtypes.