Mycoses. 2018;1–7. wileyonlinelibrary.com/journal/myc | 1 © 2018 Blackwell Verlag GmbH 1 | INTRODUCTION Fungus ball is a rare sequelae of urinary tract infections. It is difficult to treat and can lead to significant morbidity. Renal fungus ball or bezoar is a mixture of fungal cells and sloughed renal epithelial cells which form a mass capable of obstructing the urinary tract. 1 The formation of fungus ball usually results from either ongoing fungal infection in the urinary tract or as part of systemic infection. 2 Candida species is the main pathogen of renal fungus ball, although infections due to other species such as Aspergillus and Mucorales have been reported. 3 Candida fungus ball is uncommon among adult patients, but is more often seen in premature neonates as a form of disseminated candidi- asis. 4,5 It can involve renal pelvis, 6,7 ureter, 8 or urinary bladder. 9 The risk factors of urinary tract fungus ball include diabetes mellitus, neu- rogenic bladder, indwelling urinary catheter, steroids, immunosupres- sion and use of broad- spectrum antibiotics. 9,10 Fungus ball can result in serious complications such as fungaemia, 3,7 renal failure, 9 bladder rupture 9 and obstructive uropathy. 10 Because many clinicians are not familiar with such condition, treat- ment may be inappropriate. The infectious disease society of America clinical guideline on managing invasive candidiasis has included the treatment of Candida fungus ball, based on few case reports. 11 In this report, we describe a case of renal fungus ball in a patient with retro- peritoneal fibrosis, then we review the literature to identify risk factors of Candida fungus ball involving urinary tract in adults, and evaluate their treatments regimens. 2 | CASE REPORT A 37-year-old gentleman presented to the surgical casualty com- plaining from anuria. He had bilateral loin pain since 3 months, which was worsening gradually. Laboratory investigations showed raised serum creatinine of 644 umol/L. Non contrast computed tomography (NCCT) showed bilateral hydroureteronephrosis and retroperitoneal fibrosis. To relief the obstruction, percutaneous nephrostomy (PCN) was performed in both sides. Urine culture was negative. Few days later, the patient improved and his serum creatinine has normalised. Because the patient had retroperitoneal fibrosis, methylprednisolone (1 gm iv for 10 days, then 60 mg OD) was given. Follow up abdominal NCCT showed regression of previously noted fibrosis and associated hydronephrosis, and the patient was discharged. Few weeks later, the patient was admitted again because of bacte- rial urinary tract infection and displaced left PCN. Treatment consisted of ciprofloxacin and replacement of PCN. On follow up, an antegrade pyelography was performed after 1 month, which revealed a filling defect in the renal pelvis (Figure 1). Aspirated fluid culture from PCN grew Candida albicans susceptible to amphotericin B, fluconazole and flucytosine. The imaging findings and culture result were suggestive of a fungus ball. The multidisciplinary team (urologist, microbiologist and interventional radiologist) have agreed in a treatment plan which consisted of systemic fluconazole 400 mg once per day and local in- stillation of amphotericin B deoxycholate (50 mg diluted in 1 L sterile water) through PCN daily. 11 This was accompanied with ureteric stent Received: 24 October 2017 | Revised: 4 January 2018 | Accepted: 4 January 2018 DOI: 10.1111/myc.12745 CASE REPORT Renal fungus ball in a patient with retroperitoneal fibrosis: Unique complication in a rare disease Khaled Alobaid 1 | Mostafa Faty 2 | Ahmed El-Nahas 2 | Abdullatif Al-Terki 2 | Zia Khan 3 1 Medical Laboratory Department, Microbiology Unit, Al-Amiri Hospital, Kuwait City, Kuwait 2 Surgical Department, Urology Unit, Al-Amiri Hospital, Kuwait City, Kuwait 3 Microbiology Department, Faculty of Medicine, Kuwait University, Safat, Kuwait Correspondence Khaled Alobaid, Medical Laboratory Department, Microbiology Unit, Al-Amiri Hospital, Kuwait City, Kuwait. Email: khaled22m@live.com Summary Candida fungus ball is a rare presentation of urinary tract infections among adult pa- tients and is associated with considerable morbidity. Because clinical signs are not specific, diagnosis is often delayed. Furthermore, treatment is occasionally difficult, and the approach to such cases varies widely among different centers. In this report, we describe a patient with retroperitoneal fibrosis who developed a renal fungus ball. Management of this challenging case is discussed, and review of the literature is presented. KEYWORDS antifungal agents, bezoars, Candida albicans, fungus ball, retroperitoneal fibrosis, rituximab