Evaluation of abdominal fat pad aspiration cytology and grading for detection in systemic amyloidosis

Objective: To evaluate the diagnostic efficacy of abdominal fat pad aspiration cytology as a screening procedure for systemic amyloidosis and to assess the clinical usefulness of semiquantitative grading criteria of fat pad amyloid deposits. Study Design: Aspiration cytology samples from 291 cases of abdominal fat pad were retrospectively analyzed for amyloid deposits. The smears were graded semi-quantitatively. The deposits in the smears were compared with histologic evidence of amyloidosis in deeper tissues in 44 cases. Results: Retrospective analysis of 297 cases of aspiration cytology revealed amyloid in 90 cases. Follow-up biopsies from deeper tissues in 44 cases showed presence of systemic amyloidosis in 13 cases. The sensitivity and specificity of abdominal fat pad fine needle aspiration cytology was 78% and 93%, respectively. The positive predictive value was 84% and negative predictive value 90%. Conclusion: Fat pad aspiration cytology is a useful screening procedure for diagnosis of systemic amyloidosis. Patients with grade 1 deposits should not undergo a toxic therapeutic regimen on the basis of fat pad cytology alone; histologic confirmation of visceral amyloid deposition in deeper tissue is advised. Patients with grades 2 and 3 deposits may undergo suitable therapy for amyloidosis.