Medullary thyroid carcinoma. Rare cytologic findings

Area of Science:

• Cytopathology
• Endocrinology
• Oncology

Background:

• Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor arising from parafollicular C cells.
• Accurate cytologic diagnosis of MTC is crucial for timely management and patient outcomes.
• Certain cytologic features of MTC are well-established, but rare findings require further characterization.

Purpose of the Study:

• To describe and illustrate uncommon cytologic findings observed in medullary thyroid carcinoma.
• To enhance the recognition of rare diagnostic clues in fine needle aspiration (FNA) smears of MTC.

Main Methods:

• Retrospective review of FNA smears from 15 histologically confirmed MTC cases.
• Analysis of patient demographics (age, sex) and MTC subtypes (sporadic, familial).
• Detailed examination of cytologic features, including cell morphology, nuclear characteristics, and extracellular material.

Main Results:

• MTC cases were categorized into pleomorphic (8 cases) and monomorphic (7 cases) cell types.
• Observed cytologic features included varied cell shapes, intracytoplasmic red granules, intranuclear inclusions, amyloid, multinucleated cells, and granular chromatin.
• Rare findings such as grape cells, cytoplasmic nippling, elongated cytoplasmic processes, carrot-shaped nuclei, nuclear buddings, mast cell-like cells, and a Burkitt's lymphoma-like appearance were noted.

Conclusions:

• The study identified and described several rare cytologic findings in medullary thyroid carcinoma.
• These rare features, including 'grape cells' and 'carrot-shaped nuclei', can aid in the diagnosis of MTC.
• Increased awareness of these uncommon cytologic presentations can improve diagnostic sensitivity for MTC.