Lymph node examination by fine needle aspiration in patients with known or suspected malignancy

In a series of more than 2,500 fine needle aspirates from multiple body sites, over 200 were clinically identified as lymph nodes from patients with known or suspected malignancy. The material was obtained using the easily manipulated Aspir-Gun with a 21-gauge or 22-gauge needle and syringe. Of the 200 lymph node specimens, 100 (50%) were cytologically reported as positive for malignancy. Ninety cases had surgical pathology specimens available for comparison with the fine needle aspiration (FNA) specimens. For the 88 of these cases with satisfactory FNA specimens, evaluation of the FNA results showed a predictive value of a positive result of 96.8%. These results compare favorably with those of surgical biopsy. The malignancies present in the lymph nodes included numerous adenocarcinomas from the breast, melanoma and pulmonary small-cell carcinoma. Six cases are briefly presented in which the FNA diagnosis was more problematic. While histologic examination of tissues or organs remains the desirable benchmark of comparison, the appropriate utilization of FNA cytology to guide therapy, particularly in a patient with previously diagnosed malignancy, may obviate the need for an open biopsy. The technique is convenient for patient and physician, useful for outpatients, relatively painless and provides good correlation between cytologic morphology and histopathology.     

Variability in electrophoretic mobility of Gi-like proteins: effect of SDS

Two forms of Gi-like protein are resolved in both somatic cells and mouse gametes when Sigma SDS (95% grade) is used during polyacrylamide gel electrophoresis, whereas only a single species is resolved when Bio-Rad SDS (electrophoresis grade) is used. These two Gi-like proteins are likely to reflect two distinct species, since (i) the two species resolved in the presence of Sigma SDS migrate with the same electrophoretic mobility upon re-electrophoresis in the presence of Sigma SDS and (ii) exchanging Sigma SDS for Bio-Rad SDS resolves a single species, whereas exchanging Bio-Rad SDS for Sigma SDS resolves two species.