renal involvement of systemic lymphoma is a frequent feature with a prevalence of up to 50% in autopsy studies . we report a case of precursor t - cell lymphoblastic lymphoma ( t - lbl ) presenting as primary renal lymphoma ( prl ) with acute renal failure ( arf ) and bilateral nephromegaly in a patient with history of crohn s disease and prior treatment with azathioprine . the patient had a medical history of crohn s disease for which he had been treated with prednisone and azathioprine until 2006 , followed by a laparoscopic ileocaecal resection . four months before presentation , he was admitted elsewhere because of chest pain , for which acetylcystein and esomeprazole were started . at that time , serum creatinine levels were within normal limits . at the current consultation , he experienced chest pain which was continuously present during the day , and not related to exercise . physical examination revealed a blood pressure of 150/80 mmhg , but otherwise normal vital signs . except for an erythema on the malar eminences , no abnormalities were noted , especially no oedema , no pericardial friction rub , no lymphadenopathy , nor hepatosplenomegaly . further laboratory values showed haemoglobin 7.9 mmol / l , white blood cell count 13.4  10/l , 68% neutrophils , trombocytes 330  10/l , 4.4 serology of human immunodeficiency virus , hepatitis b virus ( hbv ) and hepatitis c virus ( hcv ) was negative . moreover , normal c3 and c4 and negative results of anti - double strain dna , anti - nuclear antibody , anti - nuclear cytoplasmatic antibody and anti - gbm antibody were found . urinalysis showed microscopic haematuria ( 3 + ) and proteinuria ( 1 + ) , and urine microscopic examination showed > 20 red blood cells / high - power field but no red blood cell casts . renal ultrasound showed bilateral nephromegaly of 15 , respectively , 14.6 cm in length without evidence of obstruction . at this stage , a kidney biopsy was performed which showed interstitial infiltration of medium - sized atypical lymphoid cells by light microscopy ( figure 1 ) . immunohistochemical stains of these atypical lymphocytes were strongly positive for cd3 , tdt , ki67 and cd99 and negative for cd20 and epstein  barr virus ( ebv ) . the morphology and the immunohistochemical marker profile were consistent with the who classification of precursor t - lymphoblastic leukaemia / lymphoma . total body computerized tomography , a bone marrow biopsy and a spinal fluid aspiration were performed to stage the lymphoma . apart from diffusely enlarged kidneys , these investigations were negative : neither lymphadenopathy nor pericardial effusion was seen . based on these results , the lymphoma was classified as prl and the patient started immediately with remission - induction chemotherapy receiving prednisolone , cyclophosphamide , daunorubicin , vincristin , l - asparaginase and intrathecal methotrexate for induction . after completion of the consolidation phase , kidney function improved to a serum creatinine level of 74 mol / l . recently , the patient finished his almost 2 years of maintenance treatment . at re - evaluation , no evidence of renal or extrarenal lymphoma was present and kidney function remained normal . a diffuse interstitial infiltration of medium - sized atypical lymphoid blasts with condensed chromatin without evident nucleoli , resulting in constricted tubules , was observed in light microscopy . immunohistochemical stains of these atypical lymphocytes were strongly positive for ( cytoplasmic ) cd3 ( c ) , negative for cd20 ( d ) and nuclei positive for tdt ( e ) and ki67 ( f ) . most reported cases of prl are of b - cell lineage and only a few case reports on t - cell prl have been published . to our knowledge , a precursor t - lbl is a highly aggressive neoplasm of t - cell lineage , arising from precursor t lymphoblasts . precursor t - lbl is differentiated from t - cell acute lymphoblastic leukaemia by bone marrow biopsy or aspiration , and the diagnosis precursor t - lbl is established when < 25% blasts are present . in our patient , since the kidneys do not contain lymphoid tissue , controversy exists whether prl should be considered as a distinct disease entity . some have postulated that lymphoma can arise from potential lymphoid tissue in the renal hilum   or capsule . the diagnosis of prl should only be made in the presence of a biopsy - proven lymphomatous renal infiltration , a non - obstructive nephromegaly , and in the absence of extrarenal lymphoma . a direct effect may result from ureteral obstruction , the compression of renal arteries , veins and tubules and/or bilateral parenchymal infiltration , as seen in the present case . treatment - related effects include tumour lysis syndrome , nephrotoxicity of chemotherapeutic agents and radiation nephritis . a role of immunosuppressive agents in the development of lymphoproliferative disease , predominantly ebv - associated b - cell lymphomas , has been known for many years . of note , we describe a case of t - cell lymphoma without an ebv association . a meta - analysis by kandiel et al . revealed a 4-fold increased risk of lymphoma in patients with inflammatory bowel disease , treated with azathioprine . however , independently of the use of immunosuppressive agents , patients with crohn s disease itself seem to have no substantially increased risk to develop a malignant lymphoma . the prognosis of primary renal t - cell lymphoma is difficult to estimate as prl only represents a minor fraction of the total number of primary extranodal lymphomas . one patient died within 13 months after initial presentation   the other was disease - free 17 months post - diagnosis . in general , adult patients with precursor t - lbl have a poor prognosis , despite the significant progress that has been made with the introduction of more aggressive treatment protocols . in conclusion , we report a case of primary renal t - cell lymphoma presenting with arf and bilateral nephromegaly in a patient with a history of crohn s disease and treatment with azathioprine . in patients with arf and bilateral renal enlargement , renal lymphoma is an important differential diagnostic consideration .
we report a case of acute renal failure ( arf ) and bilateral nephromegaly in a patient with a history of crohn s disease and treatment with azathioprine . 
 kidney biopsy revealed diffuse renal infiltration by precursor t - cell lymphoblastic lymphoma ( t - lbl ) . at the time of diagnosis , no extrarenal manifestations of the lymphoma were detectable and therefore the lymphoma was categorized as primary renal lymphoma ( prl ) . 
 thus far , precursor t - lbl presenting as prl has not been described before . 
 we emphasize that in patients with arf and bilateral renal enlargement , renal lymphoma is an important differential diagnostic consideration .