Biopsy of subcutaneus fatty tissue for diagnosis of systemic amyloidosis.

BACKGROUND: The diagnosis of systemic amyloidosis is determined through histological material from biopsy of different parenchymal organs, which have high diagnostic and informative value, but hide a high risk of bleeding because of the accumulation of amyloid in the vessels' wall. The main methods are kidney, liver, gastro-intestinal tract biopsy and aspiration of subcutaneous fatty tissue. The sensitivity of trans-dermal core kidney biopsy (KB) is close to 100%. The rectal biopsy is positive in 73% of cases, the biopsy of bone marrow in bout 50% and the one of gingival mucosa in 40-46 % of cases. The biopsy of subcutaneous fatty tissue (BSFT) is a new, highly sensitive method with sensitivity 73% and specificity 90%, so that it can be used as a screening test in patients without any clinical symptom or organ dysfunction. PATIENTS AND METHODS: One hundred fifteen patients, 59 male and 56 female with an average age 49.7+/-15.93 years were included in the study divided in two groups. The first group consisted of patients with kidney biopsy proved amyloidosis compared to biopsy findings from other parenchymal organs. The second group consisted of patients suspected having amyloidosis who underwent biopsies from various tissues or organs except kidney biopsy because there was contraindication.
RESULTS: One hundred fifteen biopsies of subcutaneous fatty tissue (SFT) were performed for the diagnosis of systemic amyloidosis. In order to compare the data from the BSFT to the other known and practiced till the moment methods BSFT was performed in 54 patients with proved amyloidosis by KB. In 51/54 the positive result for amyloid was confirmed. A comparison of the data in a sample of 20 patients, 11 female and 9 male, in 18/20 patients the result from BSFT is positive (90%). In coloring with Congo red are typed with KMnO4 19/54 patients, 12 female and 7 male, with average age 48.12 (SD +/-13.21). In 14/19 the amyloidosis was typed as AA (74.2%) and 5/19 non-AA, probably AL (25.8%). To reveal the meaning of so called screening-biopsy of subcutaneous fatty tissue for excluding accompanying amyloidosis in patients with significant proteinuria and/or uremia, dysglobulinemia, laboratory constellations for nephritic syndrome in immune nephropathies and chronic infections (Chronic Obstructive Lung Disease, purulent infections) with contraindications for kidney biopsy 61 screening BSFT were performed, accumulation of amyloid was defined in 37. In all of the patients the result was verified also by biopsies of rectal, gingival and stomach mucosa.
CONCLUSION: The purposeful searching and proving of amyloid in subcutaneous fatty tissue of the abdominal wall is a new, highly sensitive method. The receiving of richer material from SFT in the method "biopsy" in stead of "aspiration", makes it more reliable for proving amyloid in the case that it exists. The method is enough informative for proving not only amyloidosis AL, but also for amyloidosis AA, in treating with KMnO4. The biopsy of SFT in combination with biopsies from other mucosa can prove the accumulation of amyloid in contraindications for performing KB.