Distinguishing Primary and Metastatic Conventional Renal Cell Carcinoma From Other Malignant Neoplasms in Fine-Needle Aspiration Biopsy Specimens

Abstract

Differentiation of conventional renal cell carcinoma from other malignant neoplasms can be difficult, particularly with the limited sampling in fine-needle aspiration biopsies. Many studies have discussed the features of renal cell carcinoma in fine-needle aspiration biopsy specimens, but the significance of the cytologic features is not known. To define the significant cytologic findings that aid in differentiating renal cell carcinoma from other malignant neoplasms in fine-needle aspiration biopsy specimens. Fine-needle aspiration biopsies from 35 patients with proven primary or metastatic conventional renal cell carcinoma and from 145 patients with proven primary or metastatic non-renal cell carcinoma malignant neoplasms were assessed for the presence or absence of the following cytologic features: the heterogeneous cell population, hemosiderin deposits, small cytoplasmic vacuoles, large cytoplasmic vacuoles, low nuclear-cytoplasmic ratio, prominent nucleoli, intranuclear inclusions, irregular nuclear membranes, and smooth nuclear membranes. Statistical analysis was performed to identify the features significant in distinguishing conventional renal cell carcinoma from non-renal cell carcinoma malignancies. The presence of the heterogeneous cell population, hemosiderin deposits, small cytoplasmic vacuoles, and low nuclear-cytoplasmic ratio were each highly significant in conventional renal cell carcinoma when compared with non-renal cell carcinoma malignant neoplasms (P < .001) using univariate exact analysis. Features that were identified as being predictive of conventional renal cell carcinoma using multivariable logistic regression analysis included heterogeneous cell population, small cytoplasmic vacuoles, and hemosiderin deposits (P < .05). The presence of the heterogeneous cell population, small cytoplasmic vacuoles, hemosiderin deposits, and a low nuclear-cytoplasmic ratio aids in differentiating conventional renal cell carcinoma from other malignant neoplasms, including morphologically similar entities such as hepatocellular carcinoma, in fine-needle aspiration biopsy specimens.