Thyroid Lymphoma

Susan L. Haley, MD

Key Facts

Clinical Issues

Generally associated with lymphocytic thyroiditis

Cytopathology

Hypercellular aspirate of noncohesive lymphoid cells
Lymphoglandular bodies are usually present
May see lymphoepithelial lesions or germinal centers
DLBCL: Large, round, immature lymphocytes
EMZBCL: Mix of small atypical lymphocytes

Ancillary Tests

CD20 and CD79-a confirm B-cell immunophenotype
Flow cytometry is helpful to characterize clonality
Cytogenetic and molecular features are less extensive than in other sites

Top Differential Diagnoses

Lymphocytic thyroiditis
Undifferentiated thyroid carcinoma
Melanoma

(A) At low magnification on Diff-Quik stain, this aspirate is hypercellular and composed of singly dispersed, round cells. (B) At high magnification, the lymphoid cells are large with irregular nuclear contours, prominent nucleoli, and scant blue cytoplasm. Lymphoglandular bodies are present in the background. (C) On this Pap-stained slide, the aspirate is also cellular and dyshesive. (D) At medium magnification, there are no epithelial clusters or colloid to suggest a thyroid epithelial lesion.

TERMINOLOGY