Needle aspiration cytologic biopsy in head and neck masses.

Over 500 fine (no. 22) needle aspiration biopsies were done on head and neck lesions. The total accuracy for the series was 94.5 percent. The accuracy rates for thyroid, salivary and metastatic or benign lymph node lesions were similar: approximately 95 percent. Only lymphomatous lesions gave a lower accuracy rate: 75 percent. This method of evaluating masses in the head and neck is simple, rapid, inexpensive, well-tolerated and harmless, and is very accurate when there is close cooperation between the clinician and the cytopathologist.

The thymus according to Schambacher: medullary ducts and reticular epithelium of thymus and thymomas.

Thymomas exhibit histologically characteristic features of differentiation with great similarity to structures in fetal, normal and involuted thymus. They include pleomorphic ducts, cysts and glandular structures, which cannot be explained with the conventional views on thymus development as introduced by Hammar, but find a simple histogenetic clarification if Schambacher's concepts are accepted. With suitable fetal material Schambacher's findings can be easily confirmed. They indicate that the thymus is composed of two different types of epithelium, called here the "reticular epithelium" and the "medullary duct epithelium." The origins and development are described. The features of fetal thymus, of normal and involuted thymus, of cystic thymic lesions and of dysplastic thymus are re-examined and compared with structures found in thymomas. The observed findings suggest that thymomas are complex "organoid" epitheliomas with diversified reticular epithelial and medullary duct differentiation. Like other epitheliomas they grow slowly and may show local invasive propensities, but distant metastases remain exceptionally rare.

Appraisal of the World Health Organization classification of lung tumours.

The 1967 World Health Organization (WHO) classification of the histologic types of lung tumours has been examined in relation to 303 tumours of patients admitted to a national trial of the treatment of lung cancer. In 63 instances (20%) there was disagreement between the diagnoses of the local pathologist and the reference pathologist. The slides for these 63 tumours were reviewed by two other pathologists, and the slides for 60 tumours for which there was agreement between the local and reference pathologists were reviewed by one of the other pathologists. The main disagreement was in the diagnosis of epidermoid (squamous) tumours. It is apparent that many pathologists do not adhere to the strict criterion of the presence of keratinization or intercellular prickles or both for the diagnosis of epidermoid carcinoma. In addition, there was substantial variation in the use of subtypes within the WHO classification. Use of the revised classification proposed by the WHO would have removed a small amount of the variation from these findings but would not have affected the main discrepancy. Stricter attention to the definition of types is required for a uniform approach to the histologic classification of lung tumours.

Angiography of angiomatous lymphoid hamartoma (Castleman tumor) and a suggested pathogenesis.

The histological nature and angiographic characteristics of two cases of Castleman tumor support the concept that these tumors are hamartomatous. On angiography, both tumors exhibited a dense and homogeneous blush in the later phase. In one, in the mediastinum, hypertrophied branches of the bronchial artery gave rise to multiple irregular vascular spaces within the tumor; in the other, in the retroperitoneum, hypertrophied branches of the lumbar artery gave rise to irregular vascular channels spaced throughout the tumor. Histologically, both lesions contained numerous lymphoid follicles which, in the central portion, contained capillary vessels with thick hyalinized walls and prominent endothelial cells. A pathogenesis of hamartoma formation is suggested based on a disturbance of the normal orderly replacement of somatic cells and tissues.