Background: The aim of the present study was to assess the correlation of immunohistochemical subtyping with clinical diagnosis in order to achieve useful epidemiological data regarding amyloidosis in Turkish patients.
Method: We carried out immunohistochemical studies on 128 biopsies from various sites of 111 patients with biopsy-proven amyloidosis and, based on the results, classified the patients. We assessed the correlation of immunohistochemical subtype with clinical diagnosis and gathered epidemiological data.
Results: The sites most biopsied were kidney and rectum, followed by the testicle, liver, small intestine and bladder. Amyloid deposits showed positive staining with a single antibody in 120 biopsies. Pure amyloid A (AA) positivity was seen in 113 biopsies; six biopsies were positive for amyloid lambda (AL) and one for beta2-microglobulin (beta2MG). The clinical diagnoses of 81 patients (98 biopsies all AA positive) were suggestive of familial Mediterranean fever (FMF). Also AA positive were eight patients with tuberculosis, seven patients with rheumatoid arthritis, four patients with bronchiectasis and one patient with Crohn's disease. The biopsies from seven patients clinically suspected to have plasma cell dyscrasias were AL positive. One patient undergoing haemodialysis was beta2MG positive. Two patients without definite diagnoses showed double or triple positivity, which could not be interpreted and classified immunohistochemically.
Conclusions: This study demonstrates that the predominant association of AA amyloidosis is with FMF. It also suggests that the routine immunohistochemical study of patients with amyloidosis who are of certain ethnic backgrounds suffices for classifying the subtype of amyloid fibril protein and the related disease.