Cribriform Morular Thyroid Carcinoma: Unreported Cytological Features With Histologic Correlation and Diagnostic...

Area of Science:

• Endocrinology
• Oncology
• Cytopathology

Background:

• Cribriform morular thyroid carcinoma (CMTC) is a rare thyroid neoplasm with diagnostic challenges due to its rarity and cytomorphological overlap with papillary thyroid carcinoma (PTC).
• Distinguishing CMTC from PTC is critical, as misdiagnosis can lead to inappropriate treatment.
• Cases of CMTC lacking morules present particular diagnostic difficulties in fine-needle aspiration cytology.

Purpose of the Study:

• To identify and describe key cytomorphological features of CMTC, especially in cases lacking morules.
• To correlate cytological findings with histopathological diagnoses.
• To improve the accuracy of cytological diagnosis for rare thyroid neoplasms like CMTC.

Main Methods:

• Case presentation of a 29-year-old woman with a solitary thyroid nodule.
• Analysis of fine-needle aspiration cytology smears and cell block findings.
• Histopathological and immunohistochemical evaluation following total thyroidectomy.

Main Results:

• Cytology showed microfollicles, sheets, and papillary fragments with a "jigsaw pattern" mimicking cylindroma.
• Tumor cells exhibited nuclear elongation, crowding, and minimal irregularities, with absent colloid.
• Histopathology confirmed CMTC, despite the absence of morules; cytological patterns correlated with histological architectures.

Conclusions:

• Awareness of complex architectural patterns, such as the "jigsaw pattern," is vital for diagnosing CMTC.
• Key cytological features include absent/subtle nuclear features of PTC and absent colloid.
• Accurate cytological diagnosis of CMTC requires recognizing these specific patterns to differentiate it from PTC.