Problems in the cytologic diagnosis of the "cold' thyroid nodule in patients with lymphocytic thyroiditis.

The cytologic diagnosis of the coexistence of lymphocytic thyroiditis (LT) and thyroid neoplasms presented certain problems. Fine needle aspirations of 117 "cold' nodules were reviewed because they were or should have been diagnosed as LT. Of five cases of LT plus lymphoma, two were correctly diagnosed and three were diagnosed as LT only. All seven cases of LT plus papillary carcinoma were correctly identified, as were four of those in patients operated upon for LT plus a cellular neoplasm. From a total of 1,600 biopsies, 7 "probable' and 5 "possible' cancers were LT at operation. The causes of diagnostic error were identified as: (1) similarity of epithelial cell nuclear atypia in LT and cellular neoplasm, (2) inexperience and (3) inadequate sampling. The presence of diffuse thyroid abnormality, of significant titers of antithyroglobulin and antimicrosomal antibodies and of chemical evidence of thyroid insufficiency should alert the examiner to the possibility of LT. Large needle biopsy may clarify difficult cases.