A male patient in his 60s was admitted to our hospital with symptoms of dyspnoea, asthenia, diaphoresis and acute kidney failure. No tumour or infection was detected in initial screening. However, laboratory examination suggested that the acute kidney failure was due to an intrarenal cause, exhibiting a tubular injury pattern and indications of tumour lysis syndrome. Initial hydration therapy, paired with intravenous rasburicase, rapidly improved the kidney function. Unfortunately, the kidney function deteriorated once again, prompting a kidney biopsy that revealed an aggressive diffuse large B-cell non-Hodgkin lymphoma of the kidney. The chemotherapy, comprised of R-CHOP scheme, led to a full recovery of the kidney function and complete remission of the lymphoma. Primary renal non-Hodgkin lymphoma without nodal manifestation is rare, and its pathophysiology is poorly understood. Therapy schemes can vary significantly between cases, relying primarily on non-renal-specific haemato-oncological guidelines. Therefore, further studies are needed to develop the best therapeutic approaches.

Primary renal lymphoma (PRL) is extremely rare with an incidence of 0.7% among extranodal lymphomas. Occult renal lymphoma, which mimics medical renal disease and bilateral renal involvement, presents a diagnostic challenge to nephrologists and radiologists as the clinical and radiological findings are mostly non-specific or inconclusive. Acute kidney injury (AKI) is not an uncommon finding in renal infiltration due to malignant lymphoma. However, only 14% of cases are detected before death, and the low diagnostic rate may be due to the non-specific clinical manifestations of renal involvement, with only 0.5% of these cases presenting with AKI. Moreover, PRL is difficult to diagnose based on clinical, biochemical, and radiologic features, especially, in the case of bilateral diffuse involvement.

Herein, we report a 74-year-old woman with primary diffuse large B-cell lymphoma who presented with AKI diagnosed by ultrasound-guided needle biopsy. We also report the clinicopathologic findings of 121 PRL cases reported since 1989, by conducting a literature review of published cases.

A timely renal biopsy provides the most expedient means of establishing the diagnosis. Thus, early identification of the disease by the clinician facilitates early diagnosis toward effective treatment.

Renal affection is common in disseminated non-Hodgkin's lymphoma (NHL) which is known as secondary renal lymphoma (SRL). Primary renal lymphoma (PRL) is an exceedingly uncommon disease, which accounts for less than 1% of all renal masses. Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of NHL in both primary as well as secondary renal lymphomas. PRL is of paramount importance clinically as it is usually managed with neo-adjuvant chemotherapy followed by nephrectomy in contrast to the more frequently seen renal cell carcinoma, which is treated surgically. This outstanding difference in management challenges the longstanding approach that preoperative biopsies are not mandatory prior to nephrectomy for renal masses. Because of its relative rarity, the imaging features of PRL have been described in a few studies, and having an understanding of these typical imaging patterns is crucial for making an accurate diagnosis and differentiation from other renal malignancies. Here, we present a case of a secondary renal lymphoma and discuss its differential imaging features.

To document the clinicopathological features of primary renal lymphoma (PRL) at 2 tertiary hospitals in the western region of the Kingdom of Saudi Arabia.

Data were retrieved from all PRLs that were diagnosed at King Abdulaziz University Hospital and King Faisal Specialist Hospital and Research Centre, Jeddah, Saudi Arabia, between January 2002 and April 2022. Histopathological and immunohistochemical slides were reviewed, and additional immunohistochemistry stains were carried out in selected cases. Follow-up data were also collected.

There were 17 identified cases of PRL. The age of the patients ranged from 4-76 years (median: 50.5 years and mean: 46.8 years), 11 (64.7%) were males, and 6 (35.3%) were females. There were 12 cases of diffuse large B-cell lymphoma, 3 cases of Burkitt's lymphoma, and 2 cases of post-transplant lymphoproliferative disorder. The median follow-up duration was 22 months. The one-year overall survival rate was 71% and the 2-year overall survival rate was 43% during follow-up.

Primary renal lymphomas in Saudi patients are more common in males and seen in a relatively younger age group compared to the available worldwide data. The diagnosis of PRL is important to avoid tumor dissemination and unnecessary nephrectomy. Diffuse large B-cell lymphoma is the most common pathological type and non-germinal center B-cell is the most common subtype.

The existence of primary renal lymphoma (PRL) in the kidney has long been debated due to its extranodal location and lack of lymphatic channels. Primary renal lymphoma is extremely rare, accounting for less than 1%, and is frequently misdiagnosed as renal cell carcinoma (RCC). We present a 50-year-old man presenting with right flank pain in the last week. The computed tomography scan showed a large isodense right renal mass with a small para-aortic lymph node suspected of RCC. The patient underwent right radical nephrectomy and lymphadenectomy with an uneventful postoperative outcome. The histopathology and immunohistochemistry showed diffuse large B-cell lymphoma. Then, the patient received five-cycle chemotherapy and regional radiotherapy. Within five years of follow-up, no symptoms of recurrence. In conclusion, even though PRL is a rare tumor type. An effort should be made to make a preoperative diagnosis because PRL can be treated with systemic chemotherapy instead of other renal tumors requiring nephrectomy.

Lymphomas localized in the kidney are a rare entity that may be challenging to diagnose. We analyzed data from 10 patients with renal involvement of lymphoma diagnosed between 2009 and 2019 on fine needle biopsy from our tertiary center, and compared these with findings of 160 cases reported in the literature. Diffuse large B-cell lymphoma was the main histology subtype (40 and 38% in our sample and in the literature, respectively), followed by low-grade B-cell lymphomas, mostly from the marginal zone (MZ). Altogether, 106 patients had urological inaugural symptoms and 64 had general symptoms. Patients with urological presentation more often had renal masses than diffuse infiltration (p < 0.001), unilateral tumors (p = 0.0036) and low-grade B-cell lymphomas (17 vs 6%, p = 0.043). In both groups, nearly one-fourth of patients had diffuse (stage IV) lymphomas. Overall survival did not differ by the presence of urological/systemic symptoms, stage or aggressive lymphoma status. Notably, 3 of 10 patients from our series had MZ lymphomas associated with primary Sjögren syndrome revealed by acute kidney injury, including one where the autoimmune disease was detected. Lymphoproliferative disorders localized in the kidney are a challenging condition that can lead to detection of aggressive or diffuse lymphomas.

Renal involvement by Non-Hodgkin's lymphoma (NHL) is very rare, and involvement of the kidney as the primary site of NHL (PRNHL) is much more uncommon. Gold standard for the diagnosis of PRNHL is histology and imaging modalities although helpful are not specific. Nephrectomy has been mostly recommended for low grade lymphomas, and for high grade PRNHLs, chemotherapy without nephrectomy has been recommended as the treatment of choice. This tumor is aggressive with poor prognosis. This poor prognosis is partly because of delayed diagnosis and partly because of unnecessary surgeries, so it should be kept in mind, especially in bilateral renal tumors with unusual imaging characteristics, to take a tissue biopsy before nephrectomy. In this review, we will discuss all the detailed aspects of clinical, pathologic, and imaging characteristics of 83 cases of PRNHL reported in the last 20 years in the English literature so far. For this purpose, all the published cases of the primary non-Hodgkin's lymphoma of kidney were reviewed via a search in PubMed, Scopus, and Google Scholar, (1999-2019), using the keywords of "Primary renal lymphoma" and "Non-Hodgkin's lymphoma and kidney," "renal Non-Hodgkin's lymphoma," "renal lymphoma," and "lymphoma and kidney." There were 83 cases in the published English literature which were reviewed for this article. There was some missing information in some cases which has been recorded as "not reported."