The clinicopathological importance of a heterogeneous group of poorly differentiated thyroid carcinomas is not fully understood. Using data obtained from 303 surgically treated patients with differentiated thyroid carcinomas, the correlations between the aggressive histologic features and the clinicopathological findings, postoperative recurrences, and prognosis were retrospectively examined. In 201 cases, the carcinomas were well differentiated. The remaining 102 cases of poorly differentiated carcinomas were divided into two groups: focal-poorly differentiated (<10%) and diffuse-poorly differentiated (> or = 10%) carcinomas according to the extent of the poorly differentiated component. These poorly differentiated carcinomas were associated with high age (focal-poorly differentiated and diffuse-poorly differentiated versus well differentiated: 55 years and 59 versus 49; p < 0.0001), frequent presence of lymph node metastases (70% and 66% versus 48%; p = 0.0099) and distant metastases at diagnosis (11% and 11% versus 2%; p = 0.0098), and extrathyroidal invasion (53% and 53% versus 21%; p < 0.0001). There was independent correlation with age and the presence of extrathyroidal invasion. Cases of diffuse-poorly differentiated carcinomas showed frequent relapse (diffuse-poorly differentiated versus focal-poorly differentiated and well differentiated: 45% versus 30% and 24%; p = 0.0062) and poor prognoses (mean survival period = 9.15 versus 19.03 and 20.87 years; p < 0.0001) compared with the well and focal-poorly differentiated carcinomas. These data suggest that diffuse-poorly differentiated carcinoma is an important clinicopathological entity.

Piriform sinus fistulae are an underlying abnormality common in patients with acute suppurative thyroiditis. The fistulae arise from the hypopharynx, and end in or adjacent to the thyroid lobe. These congenital fistulae seem to be remnants of one of the pharyngeal pouches in embryonic development, but their exact origin is still controversial. Resected specimens of the thyroid glands and fistulae from 15 patients were examined immunohistochemically with rabbit antisera to human calcitonin and thyroglobulin. The fistulae were lined by squamous, columnar or ciliated epithelium, and sometimes formed branches in the thyroid lobe. Near the branches solid cell nests existed. Mucous glands, follicular structures and thymic tissue were found in the fistula. The follicular structures stained for thyroglobulin. Immunostaining for calcitonin revealed aggregates of many C cells in the thyroid near the fistula. A few calcitonin-positive cells were also found in the fistula. These findings, along with the anatomical relation of the fistulae to major structures of the neck, strongly suggest that the fistulae are remnants related to the ultimobranchial body, and that the fistulae trace the migration route of the ultimobranchial body to the thyroid gland.

To investigate the effect of hepatitis delta virus (HDV) superinfection on the long-term outcome of Japanese subjects with chronic hepatitis B virus (HBV) infection, we examined the presence of antibodies to hepatitis delta antigen (anti-HD) in serial serum samples collected from 1127 subjects with chronic HBV infection. The subjects were followed for at least 36 months (mean: 121.3 months) between 1973 and 1991. Among 69 cases where anti-HD was detected, eight (12%) developed liver cirrhosis (LC) and six (9%) developed hepatocellular carcinoma (HCC). However, among 1058 cases without anti-HD, there were 43 patients (4%) who developed LC and 29 (3%) who developed HCC. The prevalence of LC and HCC was significantly higher among the cases with anti-HD than those without anti-HD. The proportion of LC and HCC per 1000 person years was 10.46 and 7.84, respectively among cases with anti-HD, and 4.05 and 2.73 among those without anti-HD, respectively. The overall relative risk of LC and HCC was 2.58 and 2.87, respectively; 95% confidence interval (CI): LC, 1.14-5.13; HCC, 1.03-6.23. These results indicate that in the Kure district in Japan, where HDV infection of persons infected with HBV is about 6%, such superinfection increases the risk of LC and HCC.

γδ T cells have been reported to secrete a cytokine which supports the elimination of impaired epithelial cells and to maintain the normal configuration of the intestinal epithelium. 5,6) However, the precise functions of γδ T cells have not been elucidated. Some recent studies have described the effect of γδ T cells on intestinal tumor cells. γδ T cells regulated the cytotoxic activities of NK cells and CTL, of which the targets were intestinal tumor cells.7) The frequency of tumorinfiltrated γδ T cells was lowered in human well-to-moderately differentiated colorectal adenocarcinoma, 8) suggesting a relationship between γδ T cells and the formation and progression of colorectal adenocarcinoma. Notably, γδ T cells in which the variable region on the TCRδ chain is Vδ1 (Vδ1-γδ T cells) were reported to be predominant in iIEL, to recognize the major histocompatibility complex class I-related molecules A and B (MICA and MICB) and to have cytotoxic activity against intestinal tumor cells. 9)The above report also suggests that γδ T cells in iIEL may affect the formation and progression of colorectal adenocarcinoma.The present study was designed to examine the effect of γδ T cells on the formation and progression of chemically induced colorectal adenocarcinoma using γδ T cell-deficient mice. Azoxymethane (AOM) was administered to wild-type C57BL/6 mice, αβ T cell-deficient mice (TCRα-gene knockout mice) and γδ T cell-deficient mice (TCRδ-gene knockout mice) and the formation of macroscopic tumors and microscopic aberrant crypt foci in colorectal mucosa was examined. The effect of γδ T cells on the formation and progression of colorectal adenocarcinoma is discussed in the light of the results of the present study. MATERIALS AND METHODSMice Homozygous TCRα-gene knockout mice, 10) homozygous TCRδ-gene knockout mice 11) and wild-type C57BL/6 (the background of the knockout mice) were purchased from Jackson Laboratories (Bar Harbor, ME). The mice were bred and maintained in a clean air system (EBAC-S, Clea Japan Inc., Tokyo). Two-to 3-month-old mice (body weight: 15-20 g) were used for experiments. Induction of colorectal tumors and aberrant crypt foci For the induction of colorectal tumors, mice were administered AOM (10 mg/kg weight) intraperitoneally (i.p.) once