British Journal of Radiology (2006) 79, e19-e21
© 2006 British Institute of Radiology
doi: 10.1259/bjr/17821080
Isolated renal mucormycosis: an unusual cause of acute renal infarction in a boy with aplastic anaemia
R Sharma, MD1,
G Shivanand, MD1,
R Kumar, MD2,
S Prem, MD2,
H Kandpal, MD1,
C J Das, MD1 and
M C Sharma, MD3
1 Department of Radiodiagnosis, 2 Department of Hematology, 3 Pathology, All India Institute of Medical Sciences, New Delhi –110029, India
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Abstract
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Mucormycosis is an opportunistic fungal infection occurring most often in immunocompromised patients. The most common clinical presentation of infection with the fungus is rhinocerebral, followed by primary pulmonary, disseminated, gastrointestinal and cutaneous manifestations. Renal involvement in disseminated mucormycosis is well described, however, there are only few case reports describing the isolated renal mucormycosis in literature. We present an unusual case of renal mucormycosis in a patient of aplastic anaemia who presented with right flank pain and, on imaging, was found to have renal infarction and thrombosis of renal vessels. Histopathology revealed fungal hyphae infiltrating the entire kidney, renal vessels and perinephric space.
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Introduction
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Mucormycosis is a rare opportunistic infection caused by fungi of the order Mucorales and the genera Rhizopus, Absidia and Mucor. Renal involvement in disseminated mucormycosis ranges from 14% to 19% of patients [1]. Isolated renal mucormycosis is extremely rare. Only few case reports have been reported in English literature [2–9]. To the best of our knowledge, this is the first report of renal mucormycosis in a patient with aplastic anaemia presenting with renal infarction.
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Case report
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A 14-year-old boy with aplastic anaemia presented to the emergency department with a 2-day history of right flank pain. He had no fever, chills, haematuria or dysuria. The patient was on treatment with anti-thymocyte globulin (ATG) for the aplastic anaemia. Physical examination showed a normal body temperature and right flank tenderness. A mass was palpable in the lumbar region. Laboratory examination revealed low white blood cell, neutrophil and platelet counts. Blood urea and serum creatinine were raised. Chest radiograph revealed no abnormalities.
Blood and urine cultures showed no growth of either bacteria or fungus. Ultrasound combined with colour and power Doppler study (Figure 1
) revealed enlarged hypoechoic right kidney with no intrarenal vascularity. The right renal vein was enlarged and filled with thrombus, but the inferior vena cava was patent. The right main renal artery could not be visualized, suggestive of either absent flow due to long standing renal vein thrombosis or coexisting thrombosis of renal artery as well. Contrast enhanced CT scan (Figure 2) revealed enlarged non-enhancing right kidney with perinephric fluid collection. Renal radionuclide scan revealed absent perfusion of right kidney. Based on clinical presentation and fluid collection in perinephric area, presumptive diagnosis of infective aetiology for the infarction was made. Patient was started on a combination of anti-fungal (Amphotericin B) and antibacterial agents. He was also given blood and platelet transfusions. Subsequently, the patient underwent nephrectomy. Histopathology of nephrectomy specimen revealed fungal hyphae suggestive of mucormycosis infiltrating the entire right kidney, extending into renal vessels and perinephric space (Figure 3). During post-operative period, the patient developed acute respiratory distress syndrome and progressive hyponatraemia and he expired on the fifth post-operative day.
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Figure 1. Ultrasound with colour Doppler image shows(a) enlarged hypoechoic right kidney with no intrarenal vascularity (b) patent inferior venacava and no flow in renal vein.
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Figure 2. Axial contrast enhanced CT scan shows absent perfusion of right kidney with perinephric collection.
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Figure 3. Photomicrographs showing coagulative necrosis(infarct) of kidney parenchyma (A x100) with invasion of blood vessels by non-septate fungal hyphae of mucormycosis (B, PAS x200).
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Discussion
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Mucormycosis (phycomycosis, zygomycosis) is a ubiquitous, opportunistic infection caused by species in the order Mucorales of the class Zygomycetes. Patients who develop this type of infection are usually immunocompromised. The conditions that predispose to this infection are burns, diabetes mellitus, diabetic ketoacidosis, cancer, steroid therapy, alcoholism, illicit drug abuse, solid organ transplantation, malnutrition, renal failure, surgical procedures, trauma, penetrating wounds to the skin, insect bites, use of needles, broad spectrum antibiotic therapy and seropositive HIV status [10, 11]. In our case, the patient had aplastic anaemia and a low neutrophil count.
The four main presentations of mucormycosis described are rhinocerebral, pulmonary, gastrointestinal and disseminated forms [11]. Infection of single organs such as bone, heart and kidney also rarely occurs. The organism characteristically invades the walls of adjacent blood vessels, producing thrombosis and infarction, but rarely disseminates through the vessels. Renal involvement occurs as part of disseminated zygomycosis in 22% of cases, but isolated renal disease has also been documented in case reports [12].
The patients may present with fever, flank pain and tenderness, gross haematuria and pyuria. These symptoms would be consistent with a diagnosis of acute pyelonephritis. Occasionally, patients present with renal failure in bilateral disease. In a large series of renal mucormycosis reported by Gupta et al, renal infarction was observed in 12 out of 18 patients [11]. Thrombi occluding lumina of both the main renal artery and vein were observed in seven patients, as in our case. The thrombi contained the fungal hyphae in all these seven cases. Isolated renal mucormyscosis may be unilateral or bilateral. In the series reported by Gupta et al, most (13 of 18 patients) of the cases were bilateral [11], unlike our patient who had unilateral involvement.
The imaging findings include enlarged kidney with or without perinephric collection on ultrasound. Contrast enhanced CT scan may reveal enlarged kidney, with reduced or absent enhancement. There may be multiple low attenuation areas within the parenchyma suggestive of abscesses [9]. In our case, ultrasound combined with colour Doppler revealed enlarged kidney with absent perfusion. CT confirmed these findings and, in addition, there was perinephric collection. To the best of our knowledge, these imaging findings have hitherto not been described in the radiology literature.
Patients usually present with flank pain, fever and pyuria. There are no serological tests to identify mucormycosis infections. Blood and urine cultures are usually sterile. Most of the patients are treated for bacterial pyelonephritis and, not surprisingly, do not respond to antibiotics. Diagnosis requires demonstration of fungi in tissues. Most of the Mucorales will grow in routine laboratory culture media and identification is by its morphologic features, which show broad aseptate hyphae with right-angle branching.
A high index of clinical suspicion and knowledge of the varied manifestations is very important in diagnosing this condition. If a seriously ill, immunocompromised patient develops clinical features of acute pyelonephritis and ultrasound shows enlarged kidney with or without perinephric collection, contrast enhanced CT should be performed. In the presence of either renal infarction or multiple abscesses in renal parenchymal, biopsy is indicated to confirm the diagnosis.
Treatment of renal mucormycosis involves combined surgical and medical treatment. Treatment consists of extensive debridement of necrotic tissue and administration of Amphotericin B (0.6–1 mg kg–1 day–1). This treatment is usually not successful [11]. Most of the patients with renal mucormycosis will need nephroureterectomy as the fungal bezoar extends down the ureter and because the hyphal elements have a propensity for vascular invasion, causing infarction of tissue which does not respond well to simply removing the fungal cast. Overall survival for isolated renal mucormycosis is 65%. Mortality is nearly 100% for those who did not undergo nephrectomy.
In conclusion, isolated renal mucormycosis is a fatal and unusual cause of renal infarction which needs a high index of clinical suspicion. A combination of aggressive surgical and medical treatment, if instituted, may improve the outcome.
Received for publication May 3, 2005.
Revision received June 13, 2005.
Accepted for publication June 30, 2005.
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References
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Abstract
Introduction
