DICER1 Mutation-Associated Follicular Thyroid Tumor With Bizarre and Pleomorphic Nuclei

Area of Science:

• Oncology
• Genetics
• Pathology

Background:

• Thyroid carcinomas present diverse subtypes with varying prognoses.
• DICER1 mutations are linked to various neoplasms, including thyroid tumors, suggesting a role in dedifferentiation.

Observation:

• A 31-year-old female presented with a large thyroid tumor.
• The tumor harbored a somatic DICER1 hotspot mutation (p.E1705K).
• Histopathology revealed predominantly follicular microarchitecture with bizarre, pleomorphic nuclear features, but lacked overt invasive or poorly differentiated characteristics and had low proliferation indices.

Findings:

• This case presents a unique morphology of a DICER1-mutated thyroid neoplasm.
• The observed features, particularly the combination of follicular architecture with significant nuclear atypia and low proliferation, have not been previously reported in DICER1-associated thyroid tumors.

Implications:

• This case expands the morphological spectrum of thyroid tumors associated with DICER1 mutations.
• It highlights the complex role of DICER1 in thyroid tumorigenesis and its influence on tumor morphology and behavior.
• Further research is needed to fully understand DICER1's impact on thyroid tumor dedifferentiation and progression.