A morphologic and statistical comparative study of small-cell carcinoma and non-Hodgkin's lymphoma in fine-needle...

Small-cell carcinoma (SmC) and high-grade non-Hodgkin's lymphoma (NHL) are aggressive neoplasms that require prompt diagnosis and treatment. An immediate diagnosis can be obtained using fine-needle aspiration biopsy (FNAB) material from lymph nodes (LNs), which are clinically or radiologically suspicious for tumor involvement. However, in aspirates from LNs, the cytologic distinction of SmC from NHL can be challenging. The purpose of this study was to evaluate the usefulness of various cytologic features that can be used during a rapid on-site evaluation to differentiate these two entities. Twenty-seven metastatic SmC and 50 NHLs cases diagnosed by FNAB of LNs were reviewed. All NHL diagnoses (neck, 29; abdomen, 9; axilla, 6; groin, 5; and parotid, 1) were confirmed with tissue sections, flow cytometry, or immunohistochemistry. These cases were classified as follicular, 21 (42%); diffuse large B cell, 13 (26%); small lymphocytic, 7 (14%); mantle cell, 4 (8%); anaplastic large cell, 2 (4%); and 1 each (2%), Burkitt, lymphoplasmacytic, and peripheral T-cell lymphomas. Immunochemistry confirmed the cytologic diagnoses of all SmC cases (neck, 16; mediastinum, 9; abdomen, 1; and axilla, 1) with either positive chromogranin or synaptophysin. All specimens were reviewed independently by three cytopathologists who were unaware of the original diagnoses. The presence and proportion of single (noncohesive) tumor cells, lymphoglandular bodies, nuclear fragments, paranuclear blue inclusions, nuclear molding, evenly dispersed fine-granular chromatin, crush artifact, and composition of cell clusters (monomorphic vs. polymorphic) were statistically evaluated. The presence of evenly dispersed fine-granular chromatin, paranuclear blue inclusions, and nuclear fragments was each statistically significant in differentiating SmC when compared with NHL (P < 0.01). The remaining features were not significant in distinguishing SmC from NHL in LN aspirates. The identification of distinct cytologic findings such as evenly dispersed fine-granular chromatin, paranuclear blue inclusions, and nuclear fragments can be a valuable aid to accurately diagnose and differentiate metastatic SmC from NHL in FNAB preparations from LNs.