Critical role of fine needle aspiration cytology and immunocytochemistry in preoperative diagnosis of pediatric renal tumors.

Objective: To evaluate accuracy and role of immunocytochemistry (ICC) in cytologic diagnosis of pediatric renal tumors.

Study Design: Fine needle aspirates from 75 cases of pediatric renal tumors were studied. Radiologic-guided aspirations were performed, with 6-7 smears stained with Papanicolaou and Giemsa stains. Smears were screened without the knowledge of final histologic diagnosis. Subsequently, clinical details, final histology and diagnosis rendered by the original cytologist were noted to judge accuracy of diagnosis by a sensitized cytologist. Five neuroblastomas that entered close differentials for Wilms tumor were also evaluated. ICC studies were also performed after staining.

Results: Of 58 Wilms tumors, 5 were misdiagnosed; 3 renal rhabdoid tumors and 1 clear cell sarcoma were missed on cytology. Non-Hodgkin's lymphomas presenting as renal masses were accurately diagnosed on cytology, but primitive neuroectodermal tumors (n = 3) and renal cell carcinomas (n = 2) were not accurately diagnosed. Accuracy rate improved from 65% to 92% on review by a cytologist aware of cytologic features of pediatric renal tumors.

Conclusion: A good accuracy rate of diagnosis of pediatric renal tumors can be achieved by priming pathologists to typical features of tumors. Immunocytochemistry plays a supportive role in cases with atypical morphology or unusual presentations.