Nodular goiter: a histo-cytological study with some emphasis on pitfalls of fine-needle aspiration cytology.

A comprehensive comparative histo-cytological study of 48 nodular goiters from an endemic goiter region was undertaken. Practically all features observed on the biopsies were identified, although with less frequency, on the smears. In agreement with previous observations, characteristic components of nodular goiter (NG) in aspirates included small to medium size epithelial cells with regular round nuclei, honeycomb pattern, large follicles, papillae showing the previously mentioned epithelial features, oxyphilic cells, and moderate to abundant background colloid material and thyroid phagocytes (macrophages). All eight features occurred together in only 2% of the studied cases, seven in 6 (12.5%), six in 4 (8%), five in 6 (12.5%), four in 12 (25%), three in 6 (12.5%), two in 11 (23%), and one in 2 (4%) cases, respectively. Regardless of the number and combination of features present, specific identification of NG on the smears may not always be possible and diagnostic pitfalls include thyroid cyst, Hashimoto's thyroiditis, granulomatous lesions, and, more frequently, follicular neoplasia. Our findings suggest that thyroid aspirates should be analysed with critical clinico-pathological approach and surgery considered only for nodules that are clinically suspicious or unresponsive to hormonotherapy when a diagnosis of follicular neoplasia is made.

Parenchymatous thyroid nodules: a histocytological study of 31 cases from a goitrous area.

AIMS: To analyse the benefits and limitations of fine needle aspiration in the cytological differentiation of parenchymatous nodular goitres from follicular tumours in an endemic area. METHODS: Cytological smears of fine needle aspirates from 31 parenchymatous nodular goitres were studied. A sample from the punctured nodules was fixed in formalin and stained with haematoxylin and eosin for histological analysis. RESULTS: All nodules occurred in a multinodular gland, were well circumscribed, did not compress surrounding thyroid tissue, and for the most part, were unencapsulated. Two cases showed cytological features of nodular goitre, two of colloid cysts; the remaining 27 were cytologically indistinguishable from follicular lesions. CONCLUSIONS: Most of the parenchymatous nodules studied had features suggestive of follicular lesions or neoplasia, but surgical treatment should only be considered after hormone treatment has proved unsuccessful, and when they are not suspected as malignant clinically. Fine needle aspiration is useful as a diagnostic and screening aid, but the results should be interpreted with caution to prevent unnecessary surgery.

Occult papillary microcarcinoma of the thyroid--a potential pitfall of fine needle aspiration cytology?

The use of fine needle aspiration cytology detected papillary carcinoma in two patients with multinodular goitre measuring 0.7 cm and 0.9 cm in diameter, respectively. Like most of the cases from previous large series, the tumours progressed slowly as shown by absence of enlarged glands on surgical exploration and no clinical signs of metastasis after two and five years of follow up. This study shows that aspiration cytology can detect a virtually harmless occult papillary carcinoma that will oblige patients to have surgery. This very occasional "pitfall" of fine needle aspiration should not preclude this well known beneficial method from being used in the management of thyroid disease.

Cytopathology of follicular tumours of the thyroid with clear cell change.

A retrospective cytological study of nine follicular tumours of the thyroid with clear cell change was undertaken. In five clear cell adenomas and one moderately differentiated clear cell follicular carcinoma the epithelial cells occurred singly or in sheets and clusters; they sometimes assumed a trabecular or follicular pattern. The cells usually had pale diffusely vacuolated cytoplasm with ill-defined boundaries, a variable degree of anisonucleosis, nucleolar enlargement, and nuclear overlapping. Smears from a signet-ring cell adenoma contained in addition a few cells with large cytoplasmic vacuoles and compressed eccentric nuclei. In these cases a cytological diagnosis of 'follicular lesion' (or follicular neoplasia), clear cell type or signet-ring cell type, was given. A cytodiagnosis of 'carcinoma' was made only in the poorly differentiated follicular carcinoma-clear cell variant studied which showed unequivocal features of malignancy. Features suggestive of thyroid cyst, nodular goitre, Hashimoto's thyroiditis, and cell hyperactivity (marginal vacuoles, 'fire flare') were also found in the aspirated specimens of these cases of clear cell tumour of the thyroid.

Thyroid carcinoma and thyroiditis in an endemic goitre region before and after iodine prophylaxis.

Iodine prophylaxis was introduced to the moderately severe goitre endemic area in Salta, Argentina, in 1963. All thyroidectomies from a 20 year period were reviewed, and 148 thyroid malignancies carefully studied. The period from 5 to 15 years after iodization was associated with a lower frequency of follicular carcinomas and a higher frequency of papillary carcinomas than the period before and up to 5 years after prophylaxis. Lymphoid infiltration in the non-tumorous thyroid was relatively infrequent before iodine prophylaxis: it was much higher in each of the post-prophylaxis periods. These results, in agreement with other studies, support the view that an increased iodine intake is associated with an increased incidence of papillary carcinoma of the thyroid and thyroiditis.