Factors in the cytological diagnosis of alveolar cell carcinoma.

Cytologic specimens of 23 patients suffering from histologically confirmed alveolar cell carcinoma (bronchiolo-alveolar carcinoma) were examined with respect to 47 objective and subjective criteria by two independent cytologists. The following characteristics were found: typical clustering of tumor cells (concretion = tightly packed cells, often finger-like packing or rosette-formation), hyperchromasia of the nucleus, size of tumor cells like or larger than alveolar macrophages, narrow ranges of nucleus-cytoplasm ratios (mean: 0.675; SD: 0.100) despite polymorphism of tumor cells, folding of the nuclear membrane, and signs of phagocytic activity (vacuolation, excentric position of the nucleus, erythrophagocytosis). A factor analysis of the results of examinations revealed six underlying factors of diagnosis. These factors are considered to be especially important for the validity of the diagnosis of a alveolar cell carcinoma and the occurrence of misinterpretations: yield of tumor cells in the specimen, type of clustering of the tumor cells degree of preservation, qualitative attributes of the nucleus, qualitative attributes of the cytoplasm, and quantitative measurements of the size of tumor cells.