Comparative findings of lymphocytic thyroiditis and thyroid lymphoma.

OBJECTIVE

To compare the cytologic features of histologically proven lymphocytic (Hashimoto's) thyroiditis (Hashimoto's thyroitidis) and primary thyroid lymphomas (TL).

STUDY DESIGN

Clinical histories, smears (stained with Diff-Quik, Papanicolaou stain or hematoxylin and eosin [HE]) and surgical specimens (HE slides) were reviewed in 25 cases of lymphocytic thyroiditis and 12 of thyroid lymphomas.

RESULTS

Surgical specimens of thyroiditis were obtained for other medical reasons: goiter and compressive symptomatology in 21 cases and neoplasms in 4 (2 papillary carcinomas, 1 follicular carcinoma and 1 oncocytic adenoma). Seven cases were primary lymphomas, and 5 were secondary. Histologically there were 6 large B-cell lymphomas, 2 mantle cell lymphomas, 1 Burkitt lymphoma, 2 mucosal-associated lymphoid tissue lymphomas in blastic transformation and 1 of unknown type. Sensitivity for the diagnosis was 67.5% for HT and 92.3% for lymphoma.

CONCLUSION

A heterogeneous population of small and large lymphocytes was the most frequent pattern in both diseases. The presence of a monotonous population of large lymphocytes or, more rarely, of small cells indicates a probable TL. Plasma cells favor HT. Other techniques are mandatory for the differentiation of cases with inconclusive diagnoses.