ISOLATED RENAL MUCORMYCOSIS : A DIAGNOSTIC DILEMMA

Mucormycosis is a rare, life threatening invasive fungal infection caused by a group filamentous fungi of class Zygomycetes. Most cases are caused by those of the order Mucorales , which include genera Rhizopus, Mucor , Rhizomucor Absida , Apophysomyces and Cunninghamella. They are vasotrophic and angioinvasive, usually affecting immunocompromised patients. Renal involvement due to mucormycosis mostly occurs concurrently with disease affecting other parts of the body or as a part of disseminated disease. Isolated renal mucormycosis (IRM) is rarely reported in literature and mainly as unilateral. It has been documented in a few case reports, mostly from developing countries, in patients having an underlying immunocompromised state. IRM is liable to be missed clinically, especially in immunocompetent patients. It is an almost fatal disease if bilateral and diagnosed late, especially in the angio-invasive state. There is a paucity of literature on the clinical behaviour, management and outcome of bilateral IRM. We hereby present 2 cases of bilateral isolated renal mucormycosis affecting apparently immunocompetent patients with no antecedent risk factors.

CASE 1 :

30 year old Female, with no known co-morbidities , presented with history of fever with chills of 20-25 days with nausea, vomiting, abdominal pain and 2-3 episodes of hematuria. Initial investigations revealed deranged liver and kidney profile with pyuria. Further investigations, revealed Hepatitis A IgM positive, USG s/o bilateral pyelonephritis with negative blood and urine cultures. She was started empirically on 3rd generation Cephalosporins and other symptomatic treatment. Inspite of 7 days of IV antibiotics, fever and pyuria persisted. Hence, antibiotics were upgraded to Colistin , but she developed nephrotoxicity in form of rising serum creatinine and worsening electrolyte imbalances. Urine for AFB staining and culture came back negative.CT KUB was performed with revealed bilateral bulky kidneys with pyelonephritis with pelvicalyceal system fullness , however , no calculi was seen. In view of persistent pyelonephritis with back-pressure changes in both kidneys, she was planned for bilateral RIRS with DJ stenting.  Intra-operatively, it revealed lot of debris in the pelvis and pelvicalyceal system filled with fungal balls. Urine culture sent intra-operatively grew Rhizopus Microsporus. She was started on IV Amphotericin B which was continued for 14 days. She responded immediately post initiation of anti-fungals, with clearing of pyuria and improving renal functions. The patient had complete recovery of acute kidney injury in the subsequent follow up period.

CASE 2:

37 years old Male, with known no – comorbities, presented with complains of fever, uremic symptoms, altered sensorium with dysuria and decreased urine output since 4 days. On presentation, serum creatinine was 16.5mg/dl with severe metabolic acidosis. Immediately hemodialysis was initiated. Post initiation of hemodialysis, sensorium improved and acidosis was corrected. Urine output started increasing with diuretics. CT KUB revealed bilateral bulky kidneys with micro-abscesses. Initial blood and urine cultures came back negative. However, sterile pyuria and deranged kidney function persisted. After 10 days of empirical IV antibiotics, a PET scan was performed in view of persistent febrile status which revealed active disease in multiple subcentimeter sized hyperdense nodules in bilateral renal parenchyma. A renal biopsy was performed after PET scan findings which revealed invasive mucormycosis. Patient improved immediately after starting of anti-fungals which he received for a total of 2 weeks with no need for any surgical intervention like debridement / nephrectomy. His kidney function is now stable and maintaining a serum creatinine of around 2 mg/dl.

Renal mucormycosis is a rare fungal infection of the kidney , often presenting with symptoms of fever, flank pain, tenderness , gross hematuria or pyuria and renal failure , which is usually the result of near total occlusion of the renal arteries or their branches. It is particularly noted in patients with pre – existing conditions like diabetes , immunosuppression or recent COVID -19 infection. Case reports frequently highlight its high mortality and describe its rapid progression, often requiring urgent nephrectomy or other surgical interventions, in addition to anti-fungal therapy like amphotericin B. Diagnosis is challenging and requires a high index of suspicion, as typical blood and urine cultures may be sterile and imaging scans like CT scans are crucial for diagnosis. Due to extensive tissue necrosis caused by the fungus’s blood vessel invasion , surgery is often critical component of treatment to remove the dead tissue.

Isolated renal mucormycosis is a potentially rare and a fatal disease affecting immunocompromised hosts. Survival for isolated renal mucormycosis is estimated to be around 65%. Isolated renal mucormycosis affecting apparently immunocompetent patients is rare , with few previous reports in the literature. The above two cases demonstrate successful management of isolated renal mucormycosis with anti-fungals to salvage kidneys and avoid nephrectomy. We therefore hypothesize the need for early and rapid diagnosis along with aggressive multidisciplinary management including initiation of specific antifungal therapy with or without debridement is vital for successful outcome.