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 297 cases of abdominal fat pad were retrospectively analyzed for amyloid deposits. The smears were graded semiquantitatively. 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.