[Needle aspiration cytology of malignant lymphoma of the thyroid]

We have reviewed our experiences with needle aspiration cytology in five cases of malignant lymphoma of the thyroid. From the original cytologic reports, one case was correctly diagnosed as malignant lymphoma. Three were misdiagnosed as anaplastic carcinoma of the small-cell type, and two of these three were subsequently revised to malignant lymphoma at the second aspiration. Another patient was misdiagnosed as chronic thyroiditis at the first and second aspirations. Following the third aspiration, the condition was correctly diagnosed as malignant lymphoma. In the smears correctly diagnosed as malignant lymphoma, many malignant cells were distributed as isolated cells and showed monotonous features. Sometimes, cleaved cells or prominent nucleoli were visible.