A complete body autopsy has great academic significance and helps in arriving at exact diagnosis. Conventional Autopsy (CA) is an age-old method (1, 2) and reveals clinically significant diagnoses that were missed before death. However, clinical autopsy rates have been rapidly declining worldwide due to various reasons. (3, 4) Minimally invasive autopsy (MIA) has been introduced as an alternative to the conventional autopsy. It is the examination of a specific tissue taken from the site of disease and clinically relevant visceral organs to understand the pathology and identify the possible factors contributing to death and thus provides valuable feedback. (3, 5) It helps in identifying the underlying lesions which were undiagnosed ante mortem, during the course of treatment. MIA has been found to be more acceptable and feasible than a conventional autopsy as it doesn’t require dissection of whole body. This study was under taken to evaluate the potential utility and accuracy of the postmortem tissue biopsies obtained by minimally invasive autopsy technique and identify the spectrum of lesions in various biopsy samples obtained by MIA technique.

This was a three year study carried out from January 2016 to December 2018 in the department of Pathology in a tertiary care hospital. All the postmortem biopsies obtained by minimally invasive technique and received in the department of Pathology from various clinical specialties were reviewed. These biopsies are performed as blind needle biopsies after obtaining informed consent form the relatives. Majority of these biopsies were sent from Nephrology services. All the biopsy samples were fixed in 10% formalin, with routine processing and sections of 4 micron thickness were made from paraffin embedded blocks and stained with hematoxylin and eosin. The slides prepared from all the received biopsies were assessed for the presence, accuracy, adequacy and quality of the target tissue. Special Stains like Silver Methanamine and Periodic Acid Schiff (PAS) for fungi, Z-N stain for AFB and immunohistochemistry (IHC) with SV40, CD 34 & CMV was performed wherever essential.

The postmortem biopsies were received from 238 patients in the study period including 148 males and 90 females. The mean age was 36 years (range: 12–79 years). These biopsies were received from nephrology (n=101 cases), Rheumatology (n=67) and n= 70 cases form other all clinical department. The patients included 45/23 cases of renal transplant,42.SLE.The tissue biopsy samples were received from all 238 cadavers is summarized in table 1. Since the biopsies were performed as blind procedures, we tried to assess the accuracy of sample collection. The accuracy of the sampling was described as the presence of the native tissue of the organ representing the site of the biopsy. (6) Disparity of the tissue sampling was established when there is absence of the native tissue representing the site of biopsy or when there is discrepancy in the obtained tissue with regard to the site of biopsy. Table 1. Accuracy and disparity rates of various tissues obtained by MIA Type of biopsy Total number of biopsies Accuracy in biopsy sampling Disparity Percentage of accuracy (%) Renal 238 195 43 81.9 Liver 194 148 46 76.4 Lung 228 149 79 65.3 Spleen 05 03 02 60.0 Brain 05 02 03 40.0 Lymph node 03 02 01 66.6 Skin 02 02 00 100 Kidney 195 (82%) and liver 148 (76.4%) were more accurately sampled compared to lung 149 (65%), spleen 3 (60%) and lymph nodes 2 (66.6%). Analysis of Kidney biopsies. Out of 238 biopsies, 195 showed renal tissue of which 58(40%) biopsies were inadequate and diagnosis could be given in 137 adequate biopsies. The distribution of the lesions diagnosed is given in Table 2. Most of these lesions diagnosed on renal biopsy were related to the transplant status. The diagnosis of thrombotic microangiopathy related to calcineurine inhibitor toxicity, fungal infection, polyoma virus nephropathy was accurately made with the help of these biopsies. Table 2 – Histological features in various renal biopsy samples (n-195) Histological findings Number of cases Percentage (%) Acute tubular necrosis (ATN) 69 38 Inadeqaute histological findings 58 29 Chronic rejection 12 6 Diabetic nephropathy 10 5 Chronic glomerulonephritis (CGN ) 10 5 Thrombotic microangiopathy (TMA) 09 4.6 Lupus nephritis (V,IV, III, II) 08 4.1 Polyoma virus nephropathy 04 2 Acute cellular rejection 03 1.5 Acute cortical necrosis (Graft Versus Host Disease (GVHD) 02 1.0 Fungal infection 05 2.5 Hematological malignancy (AML) 01 0.5 Granulomatous inflammation (Koch’s) 01 0.5 CMV virus infection 01 0.5 Secondary malignancy 01 0.5 Bile cast nephropathy 01 0.5 . Analysis of liver biopsy: Among 148 liver biopsies, the most common finding was macro vesicular steatosis (n=60, 40%) followed by cholestasis and chronic venous congestion in 14 (12%) cases each. The biopsies did not reveal any specific finding in 34 cases. Table -3 - Histopathological analysis of liver biopsies results (n- 148) Histological findings Number of cases Macro vesicular steatosis 60 Essentially within normal limits 34 Chronic venous congestion 14 Cholestasis 14 Non specific mild portal inflammation 10 Chronic Hepatitis 06 Granulomatous Hepatitis 03 Hemorrhagic necrosis 03 Secondary malignancy 01 Hematological malignancy 01 Malaria 01 Acute hepatitis 01 Analysis of lung biopsy samples: Out of 228 tissue samples submitted, 149 (… %) showed lung tissue. The most common pathology identified was interstitial pneumonia (n-50) followed by diffuse alveolar damage (n-46). No specific pathology was seen in 29 cases. Fungal infection was identified in 9 biopsies including 4 cases of Pneumocystis jirovecii pneumonia and 5 cases of zygomycosis. These fungal infections were diagnosed in renal transplant patients. One of the biopsy showed dual infection with Cytomegalovirus (CMV) and Zygomycetes. Table -4. Histopathological analysis of lung biopsies (n= 149) Histological findings Number of cases Diffuse alveolar damage (DAD) 46 Interstitial pneumonia 50 No specific pathology identified 29 Chronic venous congestion 11 Fungal infection(Zygomycetis -05 & Pneumocystitis-04 ) 09 Granulomatous inflammation 03 CMV infection 01 . Other tissue biopsy findings: Out of 3 samples of spleen received, 2 cases show infarction while 1 cases has normal histology. Two cases of brain were received, one with normal histology and the other was autolysed. Two cases of Lymph node received show features of granulomatous lymphadenitis. Two cases of skin received show epidermal necrosis.

The technique of postmortem needle biopsy is not new a technique5 .The technique offers two major advantages over the conventional approach: it is less time-consuming and is performed at bedside before decomposition occurs, thereby, making it possible to apply a wide range of investigations that include microbiological and immunological studies, frozen sections, and electron microscopy.[7} A variability in the sampling by MIA technique was noticed in the current study;Kidney (82%) and liver (76.4%) were more accurately sampled compared to lung (65%), spleen (60%) and lymph nodes (66.6%). Nevertheless, by analyzing overall diagnostic findings in multiple organs, we were able to evaluate the diagnostic performance of MIA (91.8%). In lung, Interstitial pneumonia was the most common abnormality (50 cases-33.55%) followed by Diffuse alveolar damage (ARDS) in 46 cases (30.87%).Kurawar et al reported ARDS in 7 cases (0.55%) and Interstitial pneumonia in 103 cases (8.15%). Patel CB et al observed DAD with pneumonia in 7 cases (2.01%). CVC lung was observed in 11 cases in current study (7.38%) while it was seen in 26.44% of cases by Patel CB et al. In our study, 29 cases (19.46%) were unremarkable similar to Bhavneetkaur et al (n-58,23.2%) which differed from PratimaKhare et al (n-26 -31.9%) and Chauahan G et al (n-42, 12.53%). Fungal infection were observed in 14 cases ( Candida , Zygomycosis)by Megha S uppin et al while the current study had 9 cases which includes 4 cases of Pneumocystis carini and 5 cases of Zygomycosis. Fungal infections are difficult to diagnose ante mortem and in this study they were not detected ante mortem. Only autopsy aided these lesions, otherwise cryptic, to be diagnosed post mortem. Among kidney samples, 58 cases were inadequate for interpretation of renal biopsy. Out of 137 cases suitable for interpretation, ATN was seen in 69 cases (38%) while Sandhu et al found ATN in 27 cases (22.5%) and Swapna Patel et al in 22 cases (10.89%). Chronic graft rejection was seen in 12 cases (8.75%).Rejection is one of the biggest limitations in renal transplant procedures, where the kidney can undergo Hyper acute, acute or chronic transplant rejection[28-29].). Acute rejection is characterized by a decline in kidney function accompanied by well-established diagnostic features on kidney allograft biopsy. Acute rejection is of two types - cell mediated, and an antibody mediated cellular rejection. In our study, out of 48 cases of post renal transplant cases, 3 cases showed histological changes suggestive of an antibody-mediated rejection. Staining of peritubular capillaries with C4d and the presence of polymorph nuclear cells in peritubular capillaries is seen three patients. Polyomavirus-associated nephropathy (PVAN) is an emerging disease in renal transplant patients with variable prevalence of 1-10% and graft loss up to 80%2. Polyomavirus nephropathy is characterized histopathologically by evidence of viral replication and acute tubular injury with interstitial inflammation, tubulitis and intra nuclear inclusions. Histological evidence of PVAN was observed in 4 cases in this study. Renal biopsy revealed a predominantly tubulo-interstitial process with numerous viral inclusions, positive for SV 40 IHC staining, which is the diagnostic feature of Polyoma virus. Fungal infections among renal transplant recipients are an important cause of mortality In an Indian study 6.1% of renal transplant recipients were affected by systemic fungal infections and resulted in 63% mortality rate (11). Fungal infections were detected in 5 cases (3.64%). Zygomycosis was identified in all cases and confirmed with silver methenamine stains. Immunosuppression is the most common predisposing factor for invasive fungal infections. The fact that immunosuppression is induced therapeutically to prevent transplant rejection comes at the expense of increased risk of fungal infections. However, invasive fungi were detected only post-mortem in this study. Among liver samples, histology was unremarkable in 34 cases (22.97%) in the current study, while similar features were found by MS Bal et al and Patel PR et al in 30 cases (30%) and 233 (56.97%) respectively. The most common abnormality was found to be macrovesicular steatosis (n-60, 40.54%) similar to MS Balet al (39%) and Patel PR et al (35.69%). Chronic venous congestion was noticed in 9.45% cases which are in conformity with MS Balet al (9%). Steatosis either micro vesicular or macro vesicular is one of the earliest hepatic histopathological abnormality, often due to alcohol consumption or due to non -alcoholic fatty liver disease. Our study has some limitations like; the relatively small sample size of our study precluded the analysis of a broad spectrum of causes of death. Nevertheless, by analyzing overall diagnostic findings in multiple organs, we were able to evaluate the diagnostic importance of post mortem tissue biopsy.

First and only opportunity to identify these diseases, allowing us to better understand their role in morbidity and mortality. The practicing pathologist should be aware of the frequency and spectrum of renal and a lung lesion that may be presents in post mortem biopsy and implement a systemic approach to their evaluation.

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