Image Description
Morphologically, the most common subtype of thyroid lymphoma is diffuse large B-cell lymphoma (DLBCL) accounting for 60-90% of cases. The second most common subtype is MALT lymphoma (10-30% of cases). Many of the DLBCL cases arise by transformation of underlying MALT lymphoma. Less than 10% of thyroid lymphomas are follicular lymphoma, Burkitt lymphoma, or peripheral T-cell lymphoma subtype.
Most MALT lymphomas of thyroid arise in a background of Hashimoto thyroiditis. The native thyroid architecture is obliterated by marginal zone B-cells arranged in diffuse sheets as seen here. A cluster of small atrophic thyroid follicles is seen at the lower right corner of the image. Some cases have nodular or follicular architecture mimicking follicular lymphomas due to colonization of reactive lymphoid follicles by neoplastic cells.
Macroscopically, the gland is diffusely enlarged and firm (but not hard). The cut surface is pink-tan or it may be pale, grey-white, and fibrotic with nodular or micronodular pattern.
Most MALT lymphomas of thyroid arise in a background of Hashimoto thyroiditis. The native thyroid architecture is obliterated by marginal zone B-cells arranged in diffuse sheets as seen here. A cluster of small atrophic thyroid follicles is seen at the lower right corner of the image. Some cases have nodular or follicular architecture mimicking follicular lymphomas due to colonization of reactive lymphoid follicles by neoplastic cells.
Macroscopically, the gland is diffusely enlarged and firm (but not hard). The cut surface is pink-tan or it may be pale, grey-white, and fibrotic with nodular or micronodular pattern.