Extranodal MALT-lymphoma involving the ureter: a case report and literature review
DOI: 10.22591/magyurol.2025.3.tothf.124
Authors:
Tóth Fruzsina dr.1, Leiner Zoltán dr.1, Kovács Gábor dr.1,
Krenács László dr.2, Bodog Adina Simona dr.3
1Észak-pesti Centrumkórház – Honvédkórház, Urológiai-Andrológiai Osztály
(osztályvezető: Kovács Gábor dr., Budapest)
2Daganatpatológiai és Molekuláris Diagnosztikai Laboratórium, Szeged (laboratóriumvezető: Krenács László dr.)
3Affidea Magyarország Kft., Budapest
Summary
Introduction: Extranodal marginal zone lymphoma is a type of mucosa-associated lymphoid tissue lymphoma (MALT lymphoma), which is a slow-growing form of non-Hodgkin’s lymphoma. It arises from B cells in lymphoid tissue located outside the lymph nodes. While MALT lymphoma is the most common subtype of marginal zone lymphoma (MZL), it remains a rare entity overall, along with splenic and nodal marginal zone lymphomas. Although it can develop in various regions of the body, it most frequently affects the gastrointestinal tract. Involvement of the urothelial system is extremely rare.
Case presentation: We present the case of an 82-year-old male patient with a history of daily smoking (discontinued 11 years ago) and urological follow-up for benign prostatic hyperplasia. A follow-up CT scan after aortic aneurysm repair incidentally raised suspicion of malignancy involving the right ureter. During urological evaluation, urinary cytology was performed, followed by retrograde ureterography and uretero-renoscopy. These investigations could not exclude the presence of a space-occupying lesion observed in prior imaging, and a right ureteronephrectomy was subsequently performed.
Postoperative histopathological analysis revealed low-grade B-cell non-Hodgkin’s lymphoma. Further immunophenotyping identified the tumour as high-grade CD20-positive marginal zone lymphoma.
Conclusions: MALT lymphoma of the upper urinary tract is typically discovered incidentally. Differentiating it from other urothelial tumours is challenging, as imaging studies generally reveal only the presence of a malignancy without specifying its nature. Due to its rarity in this anatomical location, lymphoma is often not included in the urological differential diagnosis, and standardized surgical protocols are lacking. Consequently, conventional onco-urological procedures often guide preoperative decision-making.
If the diagnosis can be established prior to surgery, radical excision might be avoidable, and a more conservative, organ-preserving approach – such as targeted immunotherapy or radiotherapy – may be feasible. In all cases, histological sampling is essential to detect lymphoid infiltrates, typically composed of B cells.
In our patient, immunohistochemical staining showed CD20 and MNDA positivity, while CD5, CD23, CD30, and CD200 were negative. KP1 (CD68) demonstrated moderate cytoplasmic positivity in most tumour cells. Urethral MALT lymphoma rarely presents with subepithelial lymphoid infiltrates or lymphoepithelial lesions, more commonly involving the periureteric fat.