Stage 2 hypertension in a child with a rapidly enlarging kidney: answer

Abstract

Answers1. Burkitt's lymphoma (BL) is the most likely aetiology, especially in an endemic region. BL is a nonmetastatic, highly proliferative, multicentric tumour. It is the fastest growing tumour in humans, with a doubling rate of 24 h [2]. 2. These will include nephroblastoma, acute unilateral obstructive uropathy and renal vein thrombosis. 3. Confirmation is either by fine-needle aspirate of the tumour for cytology or renal biopsy for histopathology. Both procedures confirmed BL on admission day 4 ( Fig. 1a). There was also glomerular evidence of proliferative glomerulonephritis with Bowman's capsule ruptures and tuft adhesions (Fig. 1b). Renal biopsy findings at 4 weeks are shown in Fig. 1c. 4. It is possible that the extensive renal infiltration by Burkitt's tumour with glomerulotubular compression and destruction (Figs. 1a-c), glomerulonephritis and enhanced renin-angiotensin-aldosterone-system (RAAS) activity played dominant roles in the causation of hypertension (HTN) in this patient. The proteinuria could have been due to the combination of glomerulonephritis and systemic and intraglomerular HTN brought about by increased RAAS activity. HTN may cause high glomerular filtration pressure in both kidneys with resultant proteinuria. Hypernatraemia, hypokalaemia, avid tubular sodium reabsorption and kaliuresis suggest enhanced RAAS activity in the patient. 5. BL is highly responsive to cytotoxic drugs. Tumour remission was induced with low-dose cyclophosphamide infusion, 125 mg/m 2 /48 h for four doses [3]. He also received antitumour lysis syndrome regimen, including allopurinol [3]. Significant reduction in the renal mass occurred within 72 h of cyclophosphamide infusion. Tumour remission was subsequently maintained with cycles of combination chemotherapy that comprised cyclophosphamide 1,000 mg/m 2 /dose, methotrexate 75 mg/m 2 /dose and vincristine 1.5 mg/m 2 /dose as stat intravenous doses. Intrathecal (IT) methotrexate 12.5 mg/m 2 on chemotherapy days 1 and 8, and IT cytosine arabinoside 50 mg/m 2 on day 4 were also given. The cycle was repeated fortnightly after ensuring normal blood counts. Overall, he received only three of six prescribed cycles because he was immediately lost to follow-up after hospital discharge. His hypertension was appropriately treated with parenteral hydralazine, frusemide, oral spironolactone and lacidipine. BP normalised (100/60 mmHg) by day 10 of induction chemotherapy. The antihypertensives were subsequently discontinued without adverse events. 6. Given the severity of the glomerular lesion that included Bowman's capsule ruptures with interstitial communications (Fig. 1b) and tuft synechiae as shown in the histopathology of the second renal biopsy (Fig. 1c), progression to chronic renal failure is a potential complication.