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five categories: (i) 41 (20.5%) smears with positively malignant cells; (2) 20 (10%) smears predominantly showing chronic in- flammatory features; (3) 31 (15.5%) smears with mainly acute inflammatory changes; (4) 60 (30%) smears wSth normal cytologic fea- tures; and (5) 48 (24%) smears unsatisfac- tory for cytologic interpretation. Thir- teen patients with a positive cytology had a positive tissue biopsy for malignancy. Among the group with chronic inflammatory changes, acid-fast bacilli were identified in nine cases, and one smear showed frank tuberculous granuloma. In the unsatisfac- tory group, two cases showed malignant cells in the postbrushing sputum. There was one false-negative report for malignancy in the entire study. This study confirms the sen- sitivity and accuracy of bronchial brushing cytology in the diagnosis of various bron- chopulmonary lesions, especially malig- nancy and pulmonary tuberculosis, in India.

Carc ino id Tumorlets of the Lung wi th Meta- s t a s i s to a P e r i b r o n c h i a l Lymph Node. Re- por t o f a Case and Review of the L i t e r a t u r e . Agati, V.D., Perzin, K.H. Arthur Purdy Stout Laboratory of Surgical Pathology, Columbia University, College of Physicians and Surgeons, New York, NY 10032. Emex: 8528-8531, Excerpta Medica 1985.

A case of a rare entity, pulmonary tumor- lets that metastasized to a peribronchial lymph node, is reported. The patient, a 38-year-old man, underwent a right pneumo- nectomy for end-stage lung disease caused by bronchiectasis, chronic bronchitis, and pulmonary fibrosis. No tumors were detected on radiologic or on gross examination of the lung. Microscopically, multiple tumor- lets were identified in the fibrotic pul- monary parenchyma. Five peribronchial lymph nodes were found and appeared grossly normal. A microscopic focus of metastatic tumor, histologically identical to the pul- monary tumorlets, was discovered in one of these nodes. This metastasis was identi- fied only because a diligent search for peribronchial lymph nodes was undertaken, and because sections of each node were ob- tained. Pathologists usually do not ex- tensively examine peribronchial lymph nodes in cases of chronic inflammatory disease of the lung, even when small tumorlets are discovered as incidental findings, because it is presumed that the tumorlets have not metastasized. As shown by our case, this presumption is not always correct. Pulmo- nary tumorlets may metastasize to peribron- chial lymph nodes more frequently than has been previously recognized.

Ultrastructure of Poorly Differentiated Diffuse Epithelial Mesothelioma. Dardick, I., AI-Jabi, M., McCaughey, W.T.E.

Canadian Tumour Reference Centre, Ottawa Civic

Hospital, Ottawa, Ont. KIY, 4M9, Canada. Ultra- struct. Pathol. 7: 151-160, 1984.

In differentiating diffuse epithelial meso- thelioma from metastatic adenocarcinoma in pleu- ral and peritoneal biopsies, the number and form of microvilli and the amount and distribution of tonofilaments are thought to be the most use- ful criteria. This report details 5 cases of diffuse epithelial mesothelioma in which the characteristic fine structural features of neo- plastic mesothelial cells were markedly modified. The majority of all tumor cells were poorly dif- ferentiated in electron micrographs, particular- ly with reduced prominence or absence of inter- mediate filaments, desmosomes, intracytoplasmic lumina, and microvilli. Immunohistochemistry re- vealed the absence of carcinoembryonic antigen and the presence of cytokeratin in all cases. Comparison with a better differentiated case suggests cytologic details that are useful in dist±nguishing the poorly differentiated type of epithelial mesotheliomas from adenocarcinoma. These include a mosaic pattern of closely asso- ciated tumor cells with a few long, narrow cyto- plasmic processes lying parallel to adjacent plasma membranes, abundant cytoplasm with limited organelles usually having a polar arrangement, and nuclei with markedly disaggregated chromatin and prominent nucleolonemaltype nuclei.

Distinction of Mesothelioma from Aden0carcinoma. An Imunohistochemical Approach. Battifora, H., Kopinski, M.I. Sylvia Cowan Hi- stopathology Laboratory, Division of Anatomic Pathology, City of Hope National Medical Center, Duarte, CA 91010, U.S.A. Cancer 55: 1679-1685, 1985.

The authors investigated the expression of keratin, carcinoembyonic antigen (CEA), and an epitelial marker derived from milk fat globule membranes in 12 mesotheliomas and I00 diverse adenocarcinomas with immunohistochemical methods. The authors employed a monoclonal antibody to keratin designated as AEI, as well as the fol- lowing commercially available antisera: rabbit anti-whole human keratin, rabbit anti-CEA, and a monoclonal antibody to an epithelial factor designated as MFG-2. Expression of keratin was found in all the mesotheliomas and adenocarcino- mas with antibody AEI as well as with the rabbit antiserum; CEA was detectable in 65% of the adenocarcinomas but two mesotheliomas also re- acted weakly. With antibody MFG-2, positive re- sults were obtained in 85% of the adenocarcino- mas and in none of the mesotheliomas. All of 64 (100%) breast-, lung- and ovary-derived ade- nocarcinomas immunostained positively with anti- body MFG-2. This is of particular significance because pulmonary and ovarian adenocarcinoma frequently may be indistinguishable clinically and histologically from epithelial mesothelioma. The authors conclude that antikeratin antibodi- es are not useful in the distinction of adeno-

carcinoma from mesothelioma. Because of its