Fine needle aspiration cytology of benign adrenal cortical nodules. A comparison of cytologic findings with those of primary and metastatic adrenal malignancies.

OBJECTIVE

To determine the specific cytomorphologic criteria for diagnosing benign adrenal cortical nodule (BACN) by fine needle aspiration (FNA).

STUDY DESIGN

The smears from 162 adrenal FNA biopsies were reviewed. A diagnosis of BACN was rendered in 50 cases (31%). The cytologic features of BACN were compared to those of primary and metastatic malignant tumors of the adrenal gland, and the size of BACN as measured by computed tomography was recorded.

RESULTS

Bubbly, vacuolated, lipid background; large, cohesive tissue fragments with a syncytial nesting arrangement admixed with sinusoidal endothelial cells; and abundant oval, round, bare nuclei are the three cytomorphologic features most often seen in BACN. The combination of these three features was observed in 40 cases (89%) of BACN and was seen in 4 cases of metastatic carcinoma (6%) in which there was also coexisting adrenal cortical hyperplasia. None of the other primary or metastatic malignancies showed this combination of cytomorphologic features. The mean size of BACN was 2.5 cm, with a standard deviation of 1 cm and a range of 1-5 cm. The sizes of the four metastatic carcinomas with coexisting adrenal cortical hyperplasia were 6.5, 6, 5 and 1.5 cm, respectively (mean, 4.8).

CONCLUSION

Our data suggest that combined cytologic features of bare nuclei; bubbly, vacuolated background; and large, cohesive tissue fragments with sinusoidal endothelial cells in a small adrenal nodule (< 3.5 cm) are highly specific to FNA diagnosis of BACN.