2. Case Presentation

Our patient is a 42‐year‐old female at the time of presentation. She presented for cramping abdominal pain at an outside hospital, and there was a concern for a recently passed ureteral stone, given hydronephrosis without an identifiable calculus. Due to her initial presentation at an outside hospital, the current report was unable to retrieve initial laboratory findings. After this acute presentation, the patient continued to have pain and underwent a cystoscopy with left retrograde pyelogram that demonstrated a left ureteral stricture. This was balloon dilated, and a ureteral stent was placed.

The patient tolerated the ureteral stent very poorly, and the decision was made to remove the stent and place a percutaneous nephrostomy tube. Prior to nephrostomy tube placement, her creatinine was high at 1.7 mg/dL, white blood cell count 5.2 × 109/L, hemoglobin 14.6 g/dL, platelets 301 × 109/L, and hematocrit was low at 29.3%. Inflammatory markers and lactate dehydrogenase were not measured due to low suspicion for inflammatory conditions or cellular death. Functional testing with nuclear medicine mercaptoacetyltriglycine (MAG3) renography at this time demonstrated obstruction (the nephrostomy tube was occluded intentionally during the study) with a half‐time (T1/2) > 30 min.

Following a period of nephrostomy tube drainage, an antegrade nephrostogram demonstrated an obliterated ureteral stricture at the level of the pelvic brim (see Figures 1, 2, and 3). Her laboratory results for gastrointestinal and gynecologic malignancies were unremarkable. Similarly, a repeat computed tomography (CT) scan demonstrated no appreciable cause for extraluminal ureteral obstruction. The working diagnosis was either stricture from a passed stone or possible endometriosis with ureteral involvement. The differential also included urothelial carcinoma, IgG4‐related disease, and idiopathic retroperitoneal fibrosis [8, 9].

Figure 1: Initial CT imaging.

Figure 2: CT imaging after ureteral stent placement. (a) Coronal images after stent placement. (b) Sagittal images after stent placement.

Figure 3: Antegrade nephrostogram at time of PCN placement.

She ultimately underwent an uncomplicated ureteral reimplant with excision of scarred material outside of the distal ureter. Pathology unexpectedly demonstrated low‐grade B‐cell extranodal marginal zone lymphoma, which was the only evidence of malignancy for this patient. Immunohistochemical findings suggested that the B‐cells were positive for CD20, but were negative for CD5, CD10, CD21, CD23, CD30, CD34, BCL‐1, and BCL‐6. The CD4+ and CD8+ T cells were positive for CD3, CD5, and CD7. Ki‐67 was about 20%. The ratio for immunoglobulins IgG4/IgG was low, with MUM1 staining in some plasma cells. A clonal immunoglobulin (IGK) light chain gene rearrangement was positive.

After the diagnosis, the patient established care for her oncologic staging and management at a different institution. Due to the inability to obtain outside records for her positron emission tomography/computed tomography (PET/CT), bone marrow biopsy, oncologic treatment, and follow‐up, it was not possible to definitively determine if the current case represented primary versus secondary disease. Thus, her status clinically at the present time is not known due to her transfer to an outside hospital.