[MALACOPLAKIA OF THE URINARY BLADDER: A CASE REPORT WITH DIAGNOSTIC DIFFICULTY]

We herein report a rare case of malacoplakia of the urinary bladder that demonstrated significant diagnostic difficulty. The patient was a 65-year-old woman with a history of breast cancer, dermatomyositis, steroid-induced diabetes mellitus, and cutaneous cryptococcosis. She presented with repeated episodes of dysuria and hematuria since the age of 62. Computed tomography (CT) revealed progressive bladder wall thickening, and she was therefore diagnosed with cystitis by her primary care physician and treated with antibiotics. Her symptoms worsened at 63 years of age, and further bladder wall thickening was observed on follow-up CT, thus prompting referral to our department. Although cystoscopy revealed an erythematous and irregular mucosa, no distinct bladder tumor was observed. Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli was isolated from a urine culture, but it was considered to represent colonization, and only symptomatic treatment was provided.At 64 years of age, abdominal ultrasonography revealed multiple broad-based nonpapillary intravesical masses. Magnetic resonance imaging (MRI) revealed multiple tumors with a low signal intensity on T2-weighted images. The differential diagnoses included urothelial carcinoma, malignant lymphoma, and metastatic breast cancer. Transurethral resection of the bladder tumor (TURBT) was performed, and the largest lesion was resected for a pathological evaluation. The histopathological findings revealed the infiltration of inflammatory cells, including plasma cells, lymphocytes, and neutrophils, along with PAS- and Alcian blue-positive spherical bodies, thus suggesting disseminated cryptococcosis. However, cryptococcal antigen tests in the blood and urine were negative, and Grocott staining did not reveal any fungal elements. Ultimately, the presence of Michaelis-Gutmann bodies confirmed the diagnosis of malacoplakia of the urinary bladder.The patient's urinary symptoms improved after oral antibiotic therapy with levofloxacin. Although residual lesions were observed on follow-up cystoscopy, there were no obstructive or irritative symptoms and the patient thereafter remained under observation without any additional treatment.