Postmortem histological examination of the thyroid gland and measurement of serum antithyroid antibodies were performed in 70 patients without overt thyroid disease. Lymphocytic infiltration, antithyroglobulin hemagglutination antibody (TGHA), and antithyroid microsomal hemagglutination antibody (MCHA) were found in 12, 2, and 9 cases, respectively. The incidence of lymphocytic infiltration in females was three times that in males. Ten of the 12 cases with lymphocytic infiltration had positive antibodies (either TGHA or MCHA), while 10 of 11 patients with positive antibodies showed lymphocytic infiltration. Thus, the correlation between morphological and serological findings was highly significant at P less than 0.001. The incidence of a small thyroid gland of less than 15 g in weight was higher in patients with lymphocytic infiltration and/or positive antibodies than in patients with a normal thyroid gland. These data suggest that positive serum antithyroid antibodies in subjects without overt thyroid disease may indicate the existence of lymphocytic infiltration in the thyroid gland, that is presumably subclinical autoimmune thyroiditis.

Background. As geographic differences have been observed in the characteristics of thyroid carcinoma, an analysis was made on thyroid carcinoma in the iodine rich country of Japan. A total of 10,973 patients with histologically confirmed thyroid carcinoma registered in Japan from 1977-1986 were analyzed. Cases detected incidentally at autopsy and cases of nonepithelial tumor were excluded. This series included approximately 27% of all thyroid carcinoma cases in Japan. Results and Conclusions. Histologic distribution showed that papillary carcinoma accounted for 78.4% of cases, follicular carcinoma accounted for 17.2%, medullary carcinoma for 1.4%, squamous cell carcinoma for 0.3%, and anaplastic carcinoma for 2.7%. There is a tendency in Japan to diagnose papillary carcinoma as follicular carcinoma and to diagnose malignant lymphoma as anaplastic carcinoma. It was considered that the percentage of papillary carcinoma was higher and the percentage of follicular carcinoma and anaplastic carcinoma was lower than foregoing values. The characteristics of thyroid carcinoma in Japan were described, and the low incidence of nonpapillary carcinoma compared with papillary carcinoma was discussed in relation to iodine excess as an etiologic factor. Cancer 1992; 70:808-814.

Squamous differentiation of thyroid carcinoma was studied clinicopathologically and immunohistochemically i n 29 autopsy cases. Tumor cell nests with squamous differentiation (CNSD), which histologically resembled squamous cell carcinoma, were found i n 6 cases (20.7%). All of these 6 cases with CNSD had areas of undifferentiated carcinoma, representing 31.6% of 19 cases with undifferentiated carcinoma, and all but one case also showed coexisting papillary carcinoma. The CNSD were histologically associated with undifferentiated carcinoma in 5 cases, and with papillary carcinoma in one case; the CNSD were occasionally intermingled with these types of carcinoma, and there were findings suggesting a histological transition between the CNSD and undifferentiated carcinoma or papillary carcinoma. lmmunohistochemistry revealed that all the CNSD were reactive with antibodies for keratin and vimentin, whereas thyroglobulin and desmin were not expressed. It was concluded that the CNSD examined here were most probably due to extensive squamous differentiation (squamous metaplasia) i n undifferentiated carcinoma and papillary carcinoma. I n addition, the present results may explain the fact that cases diagnosed solely as squamous cell carcinoma sometimes show a prognosis similar to that of undifferentiated carcinoma, and may well represent extensive squamous differentiation i n such tumors rather than true squamous cell carcinoma of the thyroid. Acta Pathol Jpn 39: 306 -312, 1989.

In this investigation Hiirthle cell adenoma of the thyroid was observed by electron microscopy. The cytoplasm of the cells consisted chiefly of an accumulation of numerous irregularly shaped mitochondria. Very few other organellae were observed. In addition electron microscopy revealed various degrees of electron density in the matrix of the mitochondria. When 3 dimensional models of the mitochondria were constructed, they revealed the mitochondria to have 3 dimentional forms which sometimes looked as if they might be dividing into two or three parts. The authors felt that this indicated a process of vigorous division of mitochondria and an extension of their life span. However, it was not possible to identify the cause of this division of mitochondria. ACTA PATHOL.