Histomorphological Analysis of Lesions In Nephrectomy Specimens: A 4 Years Study In A Rural Hospital In India-Our Experience

Background: Kidney is involved in various pathological conditions ranging from non-neoplastic lesions to neoplastic diseases like renal cell carcinoma. Nephrectomy remains the treatment of choice for patient care in end stage renal diseases from various causes and neoplastic lesions. Objective: To study the histomorphological spectrum and frequency of various lesions in nephrectomy specimens. Methods: A observational retrospective research study included 33 nephrectomy specimens in the department of pathology over a period of 4 years (April 2012 to April 2016).Clinical details and radiological findings were noted from records and clinico-histomorphological correlation was done. Results: A total of 33 nephrectomy specimens were studied. Age distribution varied from 16 to 71 years with male to female ratio of 2:1.Benign lesions comprised of maximum cases (75.76%) while malignant lesion were present in 24.24% cases. Chronic nonspecific pyelonephritis was the predominant non-neoplastic finding followed by xanthogranulomatous pyelonephritis. Renal cell carcinoma was the most common malignant lesion in this study. Conclusion: Chronic nonspecific pyelonephritis leading to end stage renal disease is the commonest causative factor in our region ; may be due to consumption of hard water in rural areas.

[ Table 1] A greater percentage of both benign lesions (51.52%) and malignant lesions (15.15%) were observed in males as compared to females. Histomorphological distribution of lesions  showed that chronic nonspecific pyelonephritis (51.51%) [ Fig.1a] was the commonest finding followed by renal cell carcinoma in 8 cases (24.24%) and xanthogranulomatous pyelonephritis in 6 cases (18.18%) [Fig.1b].Age wise distribution of lesions  showed that maximum number of cases of chronic nonspecific pyelonephritis were observed in 21-40 yrs age group while renal cell carcinoma was predominant in the age group of 41-60 yrs. Benign lesions(75.76%) comprised maximum number of cases while malignant lesions were observed in 24.24% cases. The most common clinical presentation was loin pain followed by dysuria, hematuria, pyuria, fever and abdominal lump in three cases.
The commonest clinical diagnosis made was nonfunctioning kidney in 21 cases (63.63%) based on clinical and radiological findings. In 10 cases renal cell carcinoma was suspected based on radiological finding of renal mass. Out of 8 cases of RCC, 4 were clear cell type,2 were papillary type and 1 case each of chromophobe RCC and collecting duct RCC was reported.[ Fig.2-a    Severe hydronephrosis with secondary atrophy of renal parenchyma 01 01 00

Discussion
Gustav Simon, in 1869 and 1870, performed planned nephrectomy for urinary fistula and partial nephrectomy for hydronephrosis respectively. [4] Kidney is involved in variety of pathological conditions ranging from nonneoplastic to neoplastic lesions. Indications of nephrectomy depend on the type of lesion, extent of damage, general condition of patient and status of contralateral kidney.
The present study included 33 nephrectomies specimen. Age group of patients ranged from 16 to 71 years with male to female ratio of 2:1.Similar results of male preponderance were observed by Rafique et al [5] and El Malik et al [6] . Aiman et al [7] reported female preponderance in their study.
The highest percentage of patient [24.24%] were from 3 rd decade and 4 th decade which was in concordance with Rafique et al [5] . Loin pain followed by dysuria, hematuria, fever were commonest symptoms of patients in this study. Lump in abdomen was present in 3 cases who were later on diagnosed as cases of renal cell carcinoma [RCC] histopathologically.  [5] and Popat et al [9] . Out of 8 cases of RCC 5 were found in males and 3 were in females.

Out of 25 benign lesions chronic nonspecific pyelonephritis
[ Table-5] 5 cases were found in the age group 41-60 years; 2 cases in 21-40 years and one case in 61-70 years.
Grossly majority cases (4) of RCC were found in left kidney with upper pole involvement in 4 cases. Five cases showed variegated appearance with areas of necrosis and hemorrhage. [Fig. 3b&3c] One case of cystic mass in kidney suspected as RCC clinically was diagnosed as multicystic nephroma histopathologically and confirmed by immunohistochemistry study. It showed immunopositivity for Pax 8[ Fig. 3d] and immunonegativity for p63/CD30. Multicystic nephroma is a rare benign lesion of kidney with bimodal age distribution. Adult onset multicystic nephoma is more common in postmenopausal females. In our case patient was a elderly male. Two cases of XGPN in older age group were suspected clinically as well as on grossly as RCC were confirmed as XGPN on histomorphology.
In the present study out of 6 cases of XGPN 4 were seen in males due to calculus disease and 2 in females were associated with recurrent urinary tract infection. In the present study predominant cause of nephrectomy was non neoplastic lesions [75.76%] of kidney while neoplastic lesions with RCC as predominant lesion included only 24.24%. Geographical variation is found in indications of nephrectomy from review of literature. Study from Norway [10] and Nigeria [11] reported 68% and 67% respectively as a rate of nephrectomy for malignant lesions. Renal tuberculosis as a cause of nephrectomy was reported in 2.4% and 7.6% cases by Beisland et al [10] and Rafique et al [5] respectively. Renal tuberculosis is common in developing countries as compared to developed countries and patients present with sterile pyuria. But in our study we could not find renal tuberculosis as a cause of nephrectomy.
While analyzing cause of end stage renal disease or non-functioning kidney from patients clinical details, radiological and histopathological findings, it was observed that calculus renal disease was the predominant cause of ESRD in our region. This may be due to consumption of hard drinking water in large area in rural population in our region. So education and screening programs are needed in such population to reduce rate of nephrectomy due to nonneoplastic lesions especially calculus renal disease.
In comparison to various studies in the literature our findings were similar to findings of Ghalyaini et al [12] , Rafique et al and Aiman et al. Mahesh KU et al [1] reported neoplastic lesions(54.5 %) as the predominant cause of nephrectomy in his study. Ghalyaini et al [12] reported youngest patient of 7-year-old child with RCC in his series.

Conclusion
To conclude, non-neoplastic lesions of kidney comprised the most common lesions in nephrectomy specimen. RCC was the most common malignant lesion with clear cell RCC as the most common subtype.