Akira Moriuchi

CERVICAL THYMOMA and INCIDENCE OF CERVICAL THYMUS

A case of cervical thymoma in a 51‐year‐old female is reported. The tumor was located on the left side of the anterior neck just beneath the left lower lobe of the thyroid gland and there was no connection to the mediastinal thymus gland. It was well encapsulated and lobulated on the cut‐surface. Histologically, the tumor showed a mixed proliferation of lymphocytes and epithelial cells. Mitoses were frequently seen. Several tiny fragments of ectopic thymic tissue were found around the tumor. Cervical thymic tissue, considered to be the original site of the cervical thymoma, was studied and found macroscopically in 12 out of 657 patients with Basedows disease (1.8%).

Intraplacental choriocarcinoma with fetomaternal transfusion

Intraplacental choriocarcinoma is very rare, and is usually found only after maternal and fetal metastatic disease is identified. The purpose of this case report is to review the incidence and findings of intraplacental choriocarcinoma. A term placenta was investigated because the newborn was born with severe anemia (Hb 3.0 g/dL). A 2 cm nodule was noted on the surface of the amniotic membrane and grossly resembled an infarction. The tumor was examined microscopically with immunohistochemical staining for the alpha‐ and beta‐human chorionic gonadotropin (α‐hCG, β‐hCG) subunits, human placental lactogen (hPL) and Ki‐67. Microscopically, the tumor consisted of necrotic areas with proliferation of atypical trophoblastic cells and destruction of the villi and capillaries. The cells were positive for the α‐hCG, β‐hCG subunits, hPL and Ki‐67, consistent with intraplacental choriocarcinoma. The mother and newborn were investigated for the presence of metastatic disease. Computed tomography scans and magnetic resonance imaging of the mother and infant were negative for metastatic disease. Choriocarcinoma, limited only to the placenta with no evidence of metastatic disease is very rare. Primary intraplacental choriocarcinoma may frequently be overlooked or missed, and choriocarcinoma may possibly arise in the placenta more often than in retained or persistent trophoblast following pregnancy.

LIGHT AND ELECTRON MICROSCOPIC STUDY OF NONFUNCTIONING PARATHYROID CARCINOMA

A case of nonfunctioning parathyroid carcinoma in a 69‐year‐old female has been studied by light and electron microscopy. The tumor, located on the left side of the anterior neck, was well encapsulated by connective tissue but showed invasion to the capsule and to the thyroid. The tumor cells exhibited a trabecular arrangement surrounded by capillary networks but focally showed several ductal structures. They were polygonal in shape, had a large nucleus showing frequent mitosis and poor cytoplasm containing glycogen. Some tumor cells had clear and abundant cytoplasm, and resembled water‐clear cells of the parathyroid. Immunohistochemically, no thyroglobulin was demonstrated in the tumor tissue. Electronmicroscopically, the tumor cells with high N/C ratio contained poorly developed cell organelles and abundant glycogen particles. They were poor in secretory granules and had no conglomeration of lipid. Desmosomes and tonoflbrils were observed. The ratio of the reported number of nonfunctioning parathyroid carcinoma to that of functioning one in Japan was compared with that in western countries. No difference of the ratio was found between these two, when identical criteria were employed.

Cervical teratoma in a fetus and an adult. Two case reports and review of literature.

Two cases of cervical teratoma in a 30‐weeks fetus and a 26‐year‐old female have been presented. In the former case a large mass entirely occupied the anterior neck but showed no invasive or metastatic lesions, and in the other case a mass containing multiple cysts was situated in the right lower pole of the thyroid gland. Histologically, both tumors were composed of the elements derived from three germ layers including various epithelial components, cartilage, muscle, and adipose tissue. In addition to these predominantly mature elements, there were some elements showing primitive immature structure in the former case. Positive immunohistochemical staining for thyroglobulin displayed only in the former case and was observed in the compressed thyroid follicles located in the fibrous capsule and several small foci of primitive glandular structure which was an element of the tumor.

Molecular and immunohistologic analyses cannot reliably solve diagnostic variation of flat intraepithelial lesions of the urinary bladder.

We examined diagnostic variation of flat intraurothelial lesions with comparison with immunohistochemical and fluorescence in situ hybridization (FISH) analyses. Nine uropathologists diagnosed 23 biopsy samples from the urinary bladder. The samples were analyzed by immunohistochemical expression of cytokeratin 20, high-molecular-weight cytokeratin, Ki-67, p53, and p16(INK4a), and multicolor FISH using the UroVysion probe set (Vysis, Abbott, Des Plaines, IL). Diagnostic agreement for each classification and for nonneoplastic or neoplastic lesions was obtained in 8 (35%) and 16 (70%) of 23 lesions, respectively. The preference ratio of neoplasia to nonneoplasia (0.9 to 4.8) or carcinoma in situ to dysplasia (0.2 to 4.0) also varied among the pathologists. In 6 ancillary analyses, the majority of neoplastic lesions with diagnostic agreement indicated more than 2 aberrant results, whereas the majority of lesions without diagnostic agreement showed no or only 1 aberrant result. The molecular and immunohistochemical analyses can discriminate between neoplastic and nonneoplastic lesions; however, they cannot reliably solve diagnostic variation of flat intraepithelial lesions.

Ultrastructural Localization Of Endogenous Peroxidase In The Human Thyroid Gland Under Normal And Hyperfunctioning Conditions

Ultrastructural localization of human thyroid peroxidase in normal and hyperfunctioning states has been studied. Peroxidase activity was visualized ultrastructurally with a cytochemical reaction using 0.05% diaminobenzidine‐tetrahydrochloride, and hydrogen peroxide with a final concentration of 0. 0025%, 0.005%, or 0.01%, respectively, and 2% osmium tetroxide. Reaction product demonstrating the enzyme was clearly observed in cell organelles with a final concentration of hydrogen peroxide at 0.0025% or 0.005%. In the normal portion of thyroid, follicular cells demonstrated the reaction product, located mainly in rough‐surfaced endoplasmic reticulum and perinuclear cisternae and in addition a small amount of the product was found in Golgi cisternae and small vesicles dispersed throughout the subapical cytoplasm. The reaction product significantly increased in amount in the cell organelles described above and in addition, a characteristic heavy deposition of the product was observed at the external surface of the microvilli in the follicular cells of thyroid obtained from the patients with treated Basedows disease. ACTA PATHOL. JPN. 34: 553–561, 1984.

MINUTE CARCINOMA OF THE THYROID and ITS DEVELOPMENT TO ADVANCED CARCINOMA

The relationship between the size of carcinomas and their histological characteristics such as encapsulation and sclerosis was studied using 157 cases of thyroid minute carcinomas with diameters less than 10 mm. When the diameter of the tumor was less than 1 mm, encapsulated carcinomas were not found, but they were presented in a group with a larger diameter. Sclerosing carcinomas were more frequently distributed in the group with a diameter less than 5 mm. With increasing tumor size, the carcinomas were reduced markedly in number and only two cases of sclerosing carcinoma were observed with a diameter more than 8 mm. It was concluded that thyroid minute carcinomas arise as nonencapsulated carcinoma, either sclerosing or nonsclerosing, followed by encapsulation at a later time and that some of the nonsclerosing carcinomas become apparent clinically, whereas most of the sclerosing carcinomas remain clinically silent throughout the entire life of the host. ACTA PATHOL. JPN. 35 : 377–383, 1985.

ULTRASTRUCTURAL LOCALIZATION OF ENDOGENOUS PEROXIDASE ACTIVITY IN BENIGN THYROID DISEASES

Ultrastructural localization of endogenous thyroid peroxidase under benign pathological conditions such as toxic diffuse goiter, non‐toxic multinodular goiter, and adenoma, and in normal tissue was studied. Peroxidase activity was visualized by a cytochemical reaction for electron microscopy. In toxic diffuse goiters and most non‐toxic multinodular goiters, reaction product for peroxidase was observed not only in the cytoplasm but also at the external surface of microvilli of follicular cells. In normal thyroid tissues and adenomas, peroxidase was visualized only in the cytoplasm. Peroxidase activity at the external surface of microvilli of the follicular cells was found in the tissues obtained from the goiters which showed “hot” radioidine scintigram. These findings suggest that follicles with peroxidase activity at the external surface of microvilli in non‐toxic multinodular goiter are “autonomous follicles” and that peroxidase at the external surface of microvilli plays some role in active iodine uptake.

HETEROTOPIC BRAIN OF THE TONGUE

A 6‐week‐old male infant with lingual mass suffered from feeding difficulty and respiratory distress. Resected specimens revealed brain tissue composed of astroglia, oligodendroglia, ependyma, choroid plexus, neuronal cells, and primitive cells but no other elements suggestive of teratoma, therefore it was diagnosed as heterotopic brain of the tongue. ACTA PATHOL. JPN. 1397 ‐1402, 1986.

Localized Primary Amyloid Tumor of the Thyroid Developing in the Course of Hashimoto's Thyroiditis

A case of localized primary amyloid tumor of the thyroid gland developing in the course of Hashimotos thyroiditis was studied using histochemistry, immunohistochemistry and electron microscopy. The patient was diagnosed as having Hashimotos thyroiditis by histological examination of the thyroid and by the presence of a high titer of serum thyroglobulin and thyroid microsomal antibodies. In addition, the thyroid gland exhibited multiple nodular deposits of amyloid which were resistant to prior incubation with potassium permanganate. The amyloid deposits were surrounded by numerous histiocytes and multinucleated giant cells which contained small amyloid droplets in their cytoplasm. However, no amyloid deposits were observed in the walls of blood vessels. lmmunohistochemistry showed that the amyloid was strongly positive for amyloid P component, IgG and kappa light chains. Ultrastructurally, the amyloid was composed of straight fibrils with a diameter of 7 to 10 nm. Histiocytes extended slender cytoplasmic processes in a radial fashion into amyloid fibrils, which exhibited a highly organized star‐like pattern. This was considered to be an extremely rare case of localized primary amyloidosis of the thyroid, in which IgG, especially kappa light chains (AL), was present as a precursor protein. Acta Pathol Jpn 42: 210–216. 1992.