Isolated mucormycosis in a post-pyeloplasty kidney in an immuno-competent child.

A child with isolated renal mucormycosis who was successfully treated with systemic anti-fungal therapy and nephrectomy is reported.

INTRODUCTION

Zygomycosis is an opportunistic fungal infection involving multiple organ systems in an immuno-deficient individual. Isolated renal mucormycosis (IRM) has been seldom reported and is even rarer in children.[1-3] We describe a case of unilateral IRM in an operated case of bilateral pelvi-ureteric junction obstruction (PUJO). The patient was managed successfully with amphotericin B and nephrectomy.

CASE REPORT

A 7-year-old boy presented with left flank pain and intermittent fever for 10 days. He was antenatally diagnosed as bilateral PUJO. Postnatal differential renal function on Diethylenetriamine pentaacetic acid (DTPA) scan was 17%. He underwent an open dismembered pyeloplasty on the left side followed by the right side at the age of 4 months and 1.5 years respectively. He was on regular follow-up for 5 years and doing well. However, he had not visited our pediatric urology clinic in the last 1 year. The current presentation was attributed to left sided pyonephrosis and empirical intravenous antibiotics were started. The patient was hemodynamically stable and the systemic examination was unremarkable except for tenderness in the left flank. The leucocyte count, kidney function tests and blood sugar levels were within normal range. The urine culture was negative. ELISA for HIV was also negative. An ultrasonography showed grossly dilated pelvicalyceal system with thinning of renal parenchyma and echogenic debris. A contrast enhanced CT scan [Figure 1a] corroborated the sonographic findings.

Figure 1

CT scan showing grossly dilated left pelvicalyceal system with echogenic hyperdense debris (a) Before amphotericin B was started; (b) After 4 weeks of amphotericin B

A needle biopsy was done to rule out suspicion of a neoplastic lesion and the histopathology revealed presence of broad fungal hyphae interspersed with inflammatory cells. The branching pattern of the hyphae was suggestive of mucormycosis. The urine and blood samples for fungal cultures were negative. Intravenous amphotericin B (0.6–1 mg/kg/day) was initiated and his fever subsided. After 4 weeks of therapy, a repeat CT scan showed only partial resolution of the mass [Figure 1b]; hence nephrectomy was done [Figure 2]. Relative function of the left kidney was 20% on pre-nephrectomy DTPA scan. Amphotericin B was continued for 1 more week in the post operative period. The histopathology of the nephrectomy specimen revealed fungal hyphae [Figure 2a and b]. Propensity of the organism to invade the vessels was also demonstrated [Figure 2c]. His recovery was uneventful and is asymptomatic at 2 months follow up.

Figure 2

Fungal hyphae delineated by (a) Silver methenamine stain, (400X) and (b) Periodic Acid Schiff stain, (400X), (c) Renal vessel showing angio-invasion by fungal hyphae (H and E, ×200)

DISCUSSION

Zygomycosis is a fatal condition especially in an immunodeficient subject. The mortality of different forms of mucormycosis reaches 75–100% in most series. The four common clinical presentations of mucormycosis are rhinocerebral, pulmonary, gastrointestinal[4] and disseminated forms. Involvement of the kidneys has been reported in up to 20% of the cases with disseminated forms.[5] Involvement of a single organ such as bone, heart and kidney is extremely rare.[67] In 2004, Jianhong et al.[8] reported 3 pediatric cases with IRM without an underlying predisposing condition. Table 1 summarizes the cases of IRM in children aged 14 years and below, reported in English literature hitherto. Survival for IRM is estimated to be 65%.[11]

Table 1

List of pediatric isolated renal mucormycosis reported in English literature

Clinically, most patients with IRM present with fever, flank pain, tenderness, gross hematuria or pyuria.[69] It has been frequently misdiagnosed previously as renal abscess and nephroblastoma.[8] Blood and urine cultures are often negative and diagnosing mucormycosis almost always requires a high index of clinical suspicion. Histopathologic evidence of fungal invasion of the tissues is diagnostic.

There is a general consensus in the literature that early institution of amphotericin B followed by nephrectomy provides a satisfactory outcome.[9] The need for nephrectomy arises because of the propensity of the organism to invade the vessels and produce thrombosis thereby rendering the delivery of amphotericin B to the affected tissues unpredictable.[12]

Our patient was immuno-competent, although he had an anatomic abnormality in the form of PUJO, which had already been corrected surgically. The source of infection remained elusive as all diagnostic work up was negative.

A question that may arise is whether nephrectomy could have been avoided. Rogenes et al.[11] reviewed the contemporary literature and found that none of the cases of renal mucormycosis survived with amphotericin B alone. Similar experience was also reported by Gupta et al.[6] However, there are contrary reports in the literature, albeit scanty, of cases treated solely by amphotericin B. Levy[13] in 1995 reported a case of renal mucormycosis with HIV who received 4 months of amphotericin B treatment alone. The patient survived for 6 months without any symptoms related to the mucormycosis and died of an unrelated cause. Later in 1998, David et al.[14] reported successful management of an adult with AIDS and IRM with amphotericin B alone. There is a single report from India of a 10 -year -old boy with IRM that was successfully treated with amphotericin B alone.[9] Despite these isolated reports, our experience was quite to the contrary and is in tune with the trend observed in contemporary literature.

The clinical pattern of persistence of infection in the kidney and non-progression to disseminated form of mucormycosis provides emphasis to the argument that IRM must be considered as a separate disease entity as has been earlier suggested by Jianhong et al.[8] Our case also highlights that IRM has an overall favorable outcome compared to other forms of invasive mucormycosis and that early institution of amphotericin-B, combined with nephrectomy offers the best chance for cure.