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Standardized nomenclatures of tumors are mandatory for epidemiological investigations as well as for the correct interpretation of pathological diagnoses by the clinician. Not least thanks to the activity of the World Health Organization (WHO), uniform tumor nomenclatures in worldwide use have been adopted for most organs. This applies also for the thyroid, even in Switzerland, where many pathologists had formerly been convinced that only the special and rather complicated nomenclature of Langhans, adapted by Wegelin, was consistent with the special tumor situation in Switzerland, a former endemic goiter area. The simplified classification of WHO is demonstrated for the group of malignant tumors of the thyroid and the problems concerning their classification are discussed. Difficulties of classifications arise in well differentiated tumors rather than in undifferentiated, anaplastic forms. For example, it is not possible to assess unequivocally the malignancy of strongly encapsulated forms of highly differentiated follicular tumors. They are then called, rather evasively, "atypical adenomas". The difficulties do not lie in the system of classification but in the tumor's specific manner of growth, and the clinician should be aware of this. Otherwise he may overstrain the diagnostic potentialities of his pathologist.

We report a case of medullary carcinoma of the thyroid which on light microscopy showed not only the well known arrangement of cells in sheets and nests but also unequivocal follicular structures. These follicular structures are present both in the primary tumor and in lymph node metastases. Immunohistochemical investigations revealed that the cells lining the follicles produce thyroglobulin, whereas the remaining tumor tissue is positive for calcitonin and carcinoembrionic antigen. This case represents a medullary carcinoma of the thyroid with an atypical pattern consisting of both thyroglobulin and calcitonin producing cells.

Ultrastructural findings in two cases of Hashimoto's disease and two cases of focal lymphocytic thyroiditis are reported. Stimulated thyrocytes, oncocytes and degenerating thyrocytes were observed in all cases. Multinucleated thyrocytes and epithelial pseudogiant cells were identified in Hashimoto's disease only. Infiltrating lymphocytes, plasma cells, monocytes and macrophages were present in all cases. The ultrastructure of germinal centres was similar to that seen in lymphatic organs. Giant cells of both intra- and extrafollicular localization were seen in Hashimoto's disease. Most of the giant cells were macrophage-derived. Two different ways of giant cell formation were identified: besides the familiar dissolution of plasma membranes of adjacent macrophages, another mechanism of fusion was observed. At sites of contact, peculiar membrane structures were developed and disintegration of plasma membranes occurred in parts adjacent to these structures. These are not identical to desmosomes and are different from Langerhans' granules. They probably represent special organelles for the initiation of cellular fusion.

The characteristic adrenal lesions of five patients with bilateral primary adrenocortical nodular dysplasia and Cushing's syndrome developing in adolescence are presented histopathologically, and in two cases ultrastructurally. Two of the patients were siblings with additional extra-adrenal lesions such as pigmented spots on the face, myxoid cutaneous tumours and in one case familial cardiac myxoma. The adrenals were small with an uneven surface due to numerous small brown to black pigmented nodules in the inner cortex. The nodules were composed of eosinophilic giant cells filled with lipofuscin granules. The familial cases in addition revealed a pronounced disorganization of the adrenocortical architecture with capsular disruption and infiltration of periadrenal fatty tissue. The early onset of Cushing's syndrome in the second decade, the bilateral involvement of adrenal glands despite ACTH independence and the familial occurrence in combination with other peculiar rare lesions are strongly suggestive of a malformative process of the zona reticularis of the adrenal glands.

Of 48 patients with chromaffin tumors observed at the Institute of Pathology of the University of Zurich between 1971 and 1982, 10 (20.9%) had a typical associated disease: 6 patients (12.5%) had Sipple's syndrome, 2 von Recklinghausen's neurofibromatosis, and 2 others von Hippel-Lindau's disease. The origin common to all these disorders involves the neuroectoderm. In the presence of one of these diseases the possibility of an occult chromaffin tumor must be considered. Familial occurrence of chromaffin tumors was observed in 5 patients (10.5%): 3 (of two families) had Sipple's syndrome, while the other 2 (of one family) had neoplasms without associated diseases.

Male patients displaying an immotile or almost immotile sperm population are the object of an interdisciplinary study concerning a ciliary mutant that induces the "Immotile-Cilia Syndrome". Development and function of both sperm flagella and cilia are normally affected because of disturbances of the 9 + 2-arrangement. During this program, clinical, physiological, genetical and ultrastructural investigations were done. The ultrastructure of immotile spermatozoa of an infertile man did not reveal inner and outer dynein arms. Lack of the ATPase dynein which is essential for movement of the 9 + 2-axoneme, is typical for the above syndrome. In addition, symmetry of the fibrous sheath of the spermatozoa was very abnormal. The pneumologist examined normal lung function, where the ultrastructure of the cilia of the nasal mucosa displayed the dynein arms. Analysis of family tree and chromosomes by the geneticist also gave a normal result. As revealed by this infertile patient it seems likely that expression of dynein must not be identical in both germ cells and somatic cells. Such variations are therefore regarded as additional forms of the "Immotile-Cilia syndrome". Asymmetric fibrous sheaths are thought to be a result of immotile spermatid flagella, leading to an abnormal arrangement of the accessory axonemal structures. Normal early spermatid flagella of man and rat show specific movements.

The differentiation pattern of two human germ cell tumors, grown in nude mice and in vitro is described. Tumor A was an embryonal carcinoma (EC) of borderline histology with characteristics of yolk sac tumor and of seminoma; tumor B was a teratocarcinoma with yolk sac elements and syncytiotrophoblastic giant cells. The morphology of an EC as well as cytogenetic characteristics were maintained during 20 passages in nude mice from tumor A and over 11 passages from tumor B. Tumor A did not grow in vitro. Cell suspensions prepared from xenografted tumor B grew into cystic embryoid bodies in semi-solid tissue culture medium. These embryoid bodies showed cuboidal and flattened cells with microvilli, junctional complexes, peripheral microfilaments, and annulated lamellae, reminiscent of the 'inner cell mass' of a blastula and of endoderm, respectively. When such colonies were transplanted into nude mice, however, only tumors with the morphology found in the transplants appeared.

97 cases of acute necrotizing granulomatous lymphadenitis (so called "reticulozytärabszedierende Lymphadenitis") were examined retrospectively with the Warthin-Starry stain, in order to detect bacteria in patients with cat-scratch disease (CSD). 27 patients with CSD were found and among those, bacteria were demonstrated in 4. The organisms were pleomorphic rods of about 3 micron length and occurred in clumps within foci of fresh necrosis. We found the organisms in a much lower percentage than has been described in the literature. The reasons may be that many of our patients had antimicrobial treatment prior to the biopsy and that step-sectioning of the specimen may be necessary in order to detect fresh lesions. Our findings seem to confirm the observation that CSD may have a bacterial aetiology.

Hashimoto's thyroiditis is rare in endemic goiter areas. Recent investigators, however, claim an overall increase in its occurrence even in goiter areas. According to some reports the rising incidence of focal lymphocytic thyroiditis may be correlated to iodine prophylaxis. Consequently, 675 thyroid specimens were examined for the presence of focal lymphocytic thyroiditis. They had been collected at our Institute of Pathology over two 1-year periods 25 years apart (1954 and 1979), when iodine content in table salt differed considerably. Cursory examination seemed to confirm the original claim, since non-nodular tissue exhibited focal thyroiditis in 20.7% and 31.2% of cases in 1954 and 1979 respectively. Morphometric analysis, however, produced equal results for both years as far as depth of infiltration was concerned. Focal thyroiditis particularly affects non-nodular parenchyma, which was found to take up 1.5 times more area in 1979 than in 1954. Thus, infiltrates located between nodules appear more frequently as routine sections pass through larger areas of non-nodular parenchyma. However, changes in the absolute frequency or extent of focal lymphocytic thyroiditis in goiters under increasing iodine prophylaxis could not be demonstrated.

In five cases of congenital pulmonary lymphangiectasis, light microscopic features of the lungs and measurements of their lymph vessel lumina are presented. All lung sections show the same histologic characteristics: a network of partly tubular, partly cystically enlarged lymph vessels within large areas of connective tissue. The lung sections in four cases with pulmonary vein outflow obstruction, the so-called secondary form according to NOONAN et al. [28], do not differ from those in primary lymphangiectasis without obstruction in the pulmonary vein outflow area. The author's own observations are discussed together with 57 cases from the literature. Among the 26 cases of secondary lymphangiectasis are 15 children with aberrant pulmonary veins, and 11 children with hypoplasia of the left side of the heart. Clinically, both forms present with neonatal asphyxia and massive respiratory distress, usually with a fatal outcome within the first few days of life. Hyaline membrane disease may be accompanied by pulmonary lymphangiectasis to a degree that renders its distinction from congenital lymphangiectasis difficult. The lungs in 5 cases with hyaline membrane disease are compared to those in 5 cases of congenital lymphangiectasis. In the former, distended lymphatics are primarily interlobular in location, while in congenital lymphangiectasis they are also found in the subpleural and periarterial tissues. In addition, they are widened to a lesser degree than in the congenital form. In the latter the lymphatic vessel walls are markedly thickened, and the pulmonary lesions, particularly the signs of immaturity, typical for hyaline membrane disease, are lacking.