SP276A RARE CAUSE OF AKI - A CASE REPORT

Abstract

Introduction and Aims: The various common causes of community acquired AKI (Acute Kidney Injury) in the tropics include infectious diseases like acute diarrheal disease, malaria, scrub typhus & leptospirosis, envenomation, pregnancy associated AKI and toxin ingestion. We report the case of a post menopausal woman with AKI due to a rare etiology. Methods: A 54 years old post menopausal lady with diabetes mellitus diagnosed 1 month previously presented with low back ache of 3 weeks duration & leg edema of 1 week duration. She had taken Diclofenac and Paracetemol pills for 2 weeks for low back ache. Urine output ranged between 1200ml to 1500 ml/day. There was no gross hematuria or frothy urine. On examination BP was 180/110 mm Hg amd BMI was 35 kg/m2. Bony tenderness was elicited over lumbosacral region. Investigations revealed normocytic normochromic anemia, high ESR & trace protein in urine dipstick. Urine sediment was bland and urine protein creatinine ratio was 0.7. Serum creatinine at initial presentation was 1.5 mg/dl. Serum sodium and potassium were normal. Bicarbonate was 17 mmol/l. Serum calcium was 8.6 mg/dl. Plain radiograph of the spine was apparently normal. Ultrasonogram revealed normal sized kidneys and a cyst of size 1.5 X 1 cm in the lower pole of left kidney. NSAID (Diclofenac) induced AKI was considered and Diclofenac was stopped. She was started on anti hypertensive medications and diuretics. Notwithstanding, her renal function deteriorated. Serum creatinine increased to 2.5 mg/dl over 4 weeks. Drug induced AIN (Acute Interstitial Nephritis) was considered in the differential and she was subjected to percutaneous renal biopsy. Results: Light microscopy revealed multiple foci of infiltration of the renal parenchyma by atypical (malignant) cells. 4 out of 10 glomeruli revealed global sclerosis. There was no evidence of allergic AIN. Blood vessels appeared normal. Immunohistochemistry was consistent with meastatic breast cancer. Further evaluation revealed a deep seated nodule of size 2 X 2 cm in the right breast which was later confirmed to be infiltrating ductal carcinoma. CT imaging revealed lytic bone lesions in the pelvis and lumbosacral spine. Conclusions: The various common renal manifestations of internal malignancy include 1) AKI due to hypercalcemia, chemotherapeutic agents, tumor lysis syndrome, sepsis, thrombotic microangiopathy & urinary tract obstruction 2) Nephrotic syndrome due to membranous nephropathy, minimal change disease, amyloidosis etc,. Metastasis is a relatively uncommon renal presentation of internal malignancy and this case is reported for the rarity. AKI in this patient could have been due to mechanical replacement of normal renal parenchyma by metastatic malignancy. Whether any paracrine mechanism (secretion of deleterious cytokines, vasoactive substances by the tumor cells) was operational & contributing to renal failure needs further research. (Figure presented).