Diagnosis and typing of systemic amyloidosis: The role of abdominal fat pad fine needle aspiration

Department of Pathology, The Methodist Hospital, Houston TX.
CytoJournal 01/2010; 6(1):24. DOI: 10.4103/1742-6413.58950
Source: PubMed


Systemic amyloidosis (SA) has a broad nonspecific clinical presentation. Its diagnosis depends on identifying amyloid in tissues. Abdominal fat pad fine needle aspiration (FPFNA) has been suggested as a sensitive and specific test for diagnosing SA.
Thirty-nine FPFNA from 38 patients (16 women and 20 men, age range 40-88 years) during a 15-year period were reviewed. Smears and cell blocks were stained with Congo red (CR). A panel of antibodies (serum amyloid protein, serum amyloid A, albumin, transthyretin, kappa light chain and lambda light chain) was used on six cell blocks from five patients. The FNA findings were correlated with clinical and histological follow-up.
FPFNAs were positive, confirmed by CR in 5/39 (13%), suspicious in 1/39 (3%), negative in 28/39 (72%), and insufficient for diagnosis in 5/39 (13%) of cases. In all the positive cases, SA was confirmed within 2-16 weeks. Among the 28 negative cases, SA was diagnosed in 21, the rest were lost to follow-up. Among the insufficient cases, SA was diagnosed in four and one was lost to follow-up. Specificity was 100%, whereas sensitivity was 19%. SA typing using cell block sections was successful in three, un-interpretable in one, and negative in two cases.
FPFNA for SA is not as good as previously reported. This may be due to different practice setting, level of experience, diagnostic technique, or absence of abdominal soft tissue involvement. A negative result of FPFNA does not exclude SA. Immune phenotyping of amyloid is possible on cell block.

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Available from: Donna J Lager, Apr 29, 2015
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    • "Typical sources include abdominal fat-pad, kidney, rectal, gingival mucosa, or bone marrow aspirate. Currently, most samples are obtained from an abdominal fat-pad [2, 5]. Previously, gingival or rectal specimens were commonly obtained [5]. "
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    • "In a series of 151 patients, reported by Gertz et al., the subcutaneous fat aspirate was falsely negative in 28% of cases.[22] A recent study also reported lower sensitivity of fat pad aspiration for amyloid with Congo red stain.[16] Another study comparing EM, immuno- electron microscopy, and Congo red staining to evaluate abdominal fat pad specimens of suspected cardiac amyloidosis cases, reported detection of amyloid in 100% of cases by EM and in 93% cases by Congo red staining.[24] "
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