FINE-NEEDLE ASPIRATION CYTOLOGY OF AMYLOID ASSOCIATED WITH NONNEOPLASTIC AND MALIGNANT LESIONS

To assess the value of fine-needle aspiration (FNA) cytology for the d iagnosis of amyloid, we retrospectively studied all FNA cases diagnose d as having amyloid during a 6-yr period (1990-1996). FNA was performe d on both superficial and deep locations. A total of 6 cases containin g amyloid was studied, including primary medullary thyroid carcinoma, metastatic medullary thyroid carcinoma to a vertebrae, multiple myelom a, squamous-cell carcinoma of the lung metastatic to a hilar lymph nod e, primary pulmonary amyloid, and amyloid tumor in a vertebral body in a patient with primary systemic amyloidosis. Despite the location or disease association, the cytologic appearance of amyloid in all cases was similar. On Diff-Quik stain, amyloid appeared as amorphous, irregu lar, waxy, basophilic to metachromatic clumps of material. Papanicolao u stain revealed cyanophilic to organophilic clumps of material with o ccasional prominent fissures. In all 6 cases, amyloid was confirmed by Congo red stain and in 3 cases by a thioflavin T stain. In 4 of the 6 cases (67%), amyloid was associated with an underlying malignancy. In 3 cases malignant cells were admixed with the amyloid, and in another case malignancy was present at a distant site. We conclude that FNA b iopsy is a helpful initial procedure for the evaluation of patients wi th amyloid deposits. The clinical implications of amyloid found in any particular body site include both benign and malignant conditions. Th e presence of an associated neoplasm must be especially considered in the differential diagnosis of amyloid deposits. (C) 1998 Wiley-Liss, I nc.