Hürthle cell and mitochondrion-rich papillary carcinomas of the thyroid gland: an ultrastructural and immunocytochemical study.

Of 52 consecutive papillary carcinomas of the thyroid, the following cases were included in this study: one Hürthle cell papillary carcinoma, one papillary carcinoma with foci of Hürthle cells, and 10 cases of papillary carcinoma with abundant mitochondria (volumetric density of mitochondria greater than or equal to 20%). All cases were studied by light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and immunocytochemistry. Our results showed that papillary carcinomas mainly or exclusively composed of Hürthle cells are very rare; that Hürthle cell papillary carcinomas of the thyroid share the biologic characteristics and blend insidiously with the so-called mitochondrion-rich papillary carcinomas; that TEM and SEM can provide useful evidence for achieving the differential diagnosis between Hürthle cell and so-called mitochondrion-rich papillary carcinomas; and that immunocytochemical studies are useless in the aforementioned differential diagnosis.

Hürthle-cell lesions of the thyroid: a combined study using transmission electron microscopy, scanning electron microscopy, and immunocytochemistry.

Hürthle cell transformation found in 2 nodular goiters, 2 cases of Hashimoto's thyroiditis, 4 follicular adenomas, 3 follicular carcinomas, 2 papillary carcinomas and 1 anaplastic carcinoma were studied by transmission electron microscopy, scanning electron microscopy and immunocytochemistry. Ultrastructural features of Hürthle cells were identical in non-neoplastic and neoplastic lesions. Cells crammed with mitochondria, showing abnormalities in size, shape and content were prominent in most cases. The presence of distinct smooth-surfaced cells interspersed with cells with many microvilli is almost a pathognomonic scanning electron microscopic feature of benign and malignant Hürthle cell lesions. Most Hürthle cells stained positively for thyroglobulin in all cases, but no immunoreactivity for CEA and calcitonin was found.

High relative frequency of thyroid papillary carcinoma in northern Portugal.

Two hundred and twelve papillary and 40 follicular carcinomas were found in 3002 thyroid glands examined from 1931 to 1975 in four Laboratories of Pathology that fairly cover northern Portugal. There was a striking preponderance of women both in papillary (female:male = 6.9:1) and follicular carcinoma (5.7:1). Sex-specific frequency of malignancy was significantly greater in men (13.3%) than in women (8.8%). The overall papillary/follicular ratio was 5.3:1 and did not significantly change throughout the study period. Papillary/follicular ratio was not significantly greater in litoral (5.5:1) than in regions with a low iodine intake and a relatively high prevalence of goiter (3.5:1). It is advanced that this high relative frequency of papillary carcinoma in northern Portugal, even in goiter areas, may reflect the existence of a racial factor since there is not enough evidence to support the influence of dietary iodine, previous irradiation and concurrent thyroiditis.

Latent thyroid carcinoma at autopsy: a study from Oporto, Portugal.

Thirty-nine (6.5%) latent thyroid carcinomas were found in 600 thyroid glands removed at autopsy in Oporto Medical School Laboratory of Pathology. The prevalence of latent thyroid carcinomas was significantly higher in women (sex ratio 4.3:1) and in elderly people (p less than 0.005) and appeared to be independent from the existence of another malignant neoplasm. The mean thyroid weight and the concurrent thyroid pathology of patients with thyroid carcinomas were not significantly different from those of patients without them. The study of cervical lymph nodes in the first 400 autopsies did not show any significant difference concerning histologic pattern, number of germinal centers and sinus histiocytosis between patients with thyroid carcinomas and those without them. Further investigation is required to evaluate the role of host factors on the peculiar characteristics of latent thyroid carcinomas.