amyloidosis is a potentially fatal condition characterized by extracellular deposition of nonbranching protein fibrils in organs . this devastating condition is mainly caused by plasma cell disorders and numerous inflammatory diseases including autoimmune and chronic infectious diseases [ 2 , 3 ] . demonstration of amyloid deposits in biopsy specimens is the only way of establishing the diagnosis of amyloidosis [ 4 , 5 ] . the sensitivity and specificity of histopathology varies greatly according to where the tissue biopsy is obtained [ 5 , 6 ] . sensitivity of biopsy samples from visceral organs is higher ; however , it requires more invasive procedures with bearing higher risk of complications , such as bleeding , hematoma , and perforation . abdominal fat pad , gingiva , and rectum are the most common initial biopsy sites because of their ease of accessibility , low complication rate , and lower costs . however , diagnostic yield of these biopsies is somewhat lower compared to visceral organ biopsies . labial salivary glands are a good biopsy site for the demonstration of amyloid deposits . minimally invasive minor salivary gland biopsy ( msgb ) is an easy procedure which can be performed by nonsurgical physicians with lower risk complications . since rheumatic diseases are a common cause of secondary amyloidosis and abovementioned advantages increased use of msgb in rheumatology departments . however , there is inconsistency in the literature about its utility and diagnostic yield [ 7 , 911 ] . hence , we aimed to investigate efficacy of this procedure for the assessment of amyloidosis in our patient population . we have examined minimally invasive msgb from 35 patients during the time period between january 2010 and september 2012 in this retrospective cohort study . all patients were recruited from the same rheumatology department and all had chronic rheumatic diseases . all patients underwent a workup including renal and hepatic function tests , complete blood count , erythrocyte sedimentation rate , c - reactive protein , urinary protein excretion , and urinary cast examination . the clinical or laboratory symptoms / findings suggestive of amyloidosis were presence of significant or worsening proteinuria , renal impairment , refractory diarrhea , neuropathy , and restrictive cardiomyopathy . when msgb was negative but there was a high suspicion for amyloidosis a kidney , duodenum , or rectal biopsy was performed for further investigation . furthermore , other allied departments in the management of patients performed other tissue biopsies with their own decisions ( i.e. , duodenal / intestinal biopsy for diarrhea in gastroenterology or kidney biopsy for impaired renal function in nephrology ) . all biopsies were carried out with minimally invasive technique , a modified technique defined by friedman et al . . in our method minor salivary glands of lower lip are palpated and local anesthesia ( prilocaine ) is applied with 30 gauge syringe . a 1 - 2  mm incision is made on lip mucosa near glandular salivary tissues . homeostasis after incision was provided simply with 15 minutes of external compression without a suture . minor salivary glands were fixed in formalin , processed , embedded in paraffin , stained with congo red , and examined by polarized light microscopy . in defined time period 37 biopsies were performed from 35 patients with suspected diagnosis of amyloidosis . in 2 patients the most common underlying disease was familial mediterranean fever followed by ankylosing spondylitis and rheumatoid arthritis . the procedure was well tolerated in all patients without any major complication . in 11 patients amyloidosis was diagnosed with msgb ( table 2 ) . of these 30 patients had biopsy from other sites : duodenum , bone marrow , rectum . or kidney . sixteen of them were identified as being of aa type and two were al type amyloidosis . systemic amyloidosis is a progressive and fatal disease unless diagnosed early and treated if possible . therefore , demonstration of amyloid accumulation within tissues is the only means of diagnosis of amyloidosis , making tissue biopsy essential . in our cohort hence , tissue biopsies can be obtained from any organ but amyloid deposits range from massive to subtle in these organs . urinary protein excretion , an early finding of amyloidosis , was regularly ordered in our department for screening of proteinuria which was the most common indication of msgb in our study . moreover , deposits may not be present in tissue biopsies from compromised organs like kidney and salivary glands . all these may explain low sensitivity of msgb found in our study compared to other studies that report 83 to 100% sensitivity [ 2 , 9 , 16 ] . since minimally invasive msgb method is well tolerated it can be repeated sometime later after the initial procedure . we repeated msgb 6 months after the first biopsy in two patients which confirmed the diagnosis of amyloidosis in one of them . the major drawback of minimally invasive msgb is that the amount of tissue obtained is relatively small [ 8 , 12 ] . in our cohort the amount of salivary tissue was adequate for the histopathologic examination in all patients without major complications . the advantages of minimally invasive msgb method are avoidance of more invasive methods , need for a small incision , any prerequisite for the procedure , quite low risk of bleeding and nerve damage , applicability in an outpatient setting , and rapid healing [ 1 , 12 ] . local and transient swelling , numbness , and pain were the only reported untoward effects by the patients related to the procedure . a substantial number of our patients had fmf as underlying disorder which is somewhat different from other geographic regions [ 10 , 16 ] . however , we do not think that it is a major concern since the mechanism leading to amyloidosis is persistent inflammation as observed in other rheumatic diseases . tissue biopsies other than msgb were not routinely performed in all patients ; therefore , we could not compare sensitivity and specificity of msgb with other biopsy sites . msgb is a safe and simple method for the evaluation of amyloidosis which can be performed in an outpatient setting without preparation for procedure . we suggest extensive use of this minimally invasive method with consideration of its own drawbacks such as dependence of pathologists ' skill and patients ' amyloid load .
background . 
 systemic amyloidosis is a potentially fatal condition , unless diagnosed and treated before development of irreversible organ damage . 
 demonstration of amyloid deposits within tissue biopsies is only definitive diagnostic method , which makes appropriate selection of biopsy site essential . 
 herein , 
 we evaluated efficacy of minimally invasive minor salivary gland biopsy ( msgb ) for the diagnosis of amyloidosis . methods . 
 we analyzed 37 biopsies taken from 
 35 patients . 
 suggestive findings for amyloidosis were significant proteinuria , renal impairment , refractory diarrhea , neuropathy , and restrictive cardiomyopathy . 
 minor salivary gland was the initial biopsy site in all subjects . 
 when msgb was negative but there was a high suspicion for amyloidosis , a kidney , duodenum , 
 or rectal biopsy was performed for further investigation . 
 results . 
 mean age of patients was 45.4 and 21 were female . in 11 patients amyloidosis 
 was diagnosed 
 with msgb . in overall 18 patients 
 were diagnosed with amyloidosis . 
 sixteen of them were identified as being of aa type and two were al type amyloidosis . 
 the sensitivity of minimally invasive msgb is 61.1% for diagnosing amyloidosis in this study . 
 conclusion . 
 msgb is a safe and simple method for the diagnosis 
 of amyloidosis which can be performed in an outpatient setting . 
 we suggest extensive use of this minimally invasive method .