Small-cell-type poorly differentiated squamous cell carcinoma of the lung. Cytologic, immunohistochemical and nuclear DNA content analysis.

The relationship between the nuclear DNA content, the immunohistochemical findings, the clinical characteristics (tumor volume doubling time and survival) and the cytomorphologic features of small cell poorly differentiated squamous cell carcinoma of the lung was studied in ten cases. There were no significant correlations between the immunohistochemical stainings for neuron-specific enolase and keratin and the clinical characteristics in these cases. The DNA histogram patterns were classified as type I or type II, depending on the degree of dispersion of values. There was no relationship between the immunohistochemical findings and the DNA histogram patterns. Only the DNA histogram patterns were related to some of the clinical characteristics: patients with type II histograms had significantly shorter tumor volume doubling times than did patients with type I histograms. Such information may aid in distinguishing the small cell type of poorly differentiated squamous carcinoma from classic small cell carcinoma of the lung, with which it may be confused.