Representative flow cytometric analysis of small-cell carcinoma. A 45-year-old man presented with shortness of breath, facial swelling, weight loss, fever, and a right hilar mass involving the superior vena cava, and he was suspected to have an aggressive lymphoma. a FNA revealed the presence of cells with a high N:C ratio, present individually and in clusters. b By flow cytometric analysis, the neoplastic cells were found to be negative for hematopoietic cell markers, including CD45, B-cell, and T-cell markers (data not shown), but they were positive for CD56, but not CD16, consistent with small-cell carcinoma.