Case report
A 60-year-old man with a history of gout and prostate adenoma consulted in August 2019 for deterioration of the general condition and a significant weight loss of 35 kg. Clinical examination and radiological investigation found multiple lymphadenopathies (cervical, axillary, inguinal, mediastinal, abdominal, intra, and retroperitoneal) associated with hepatosplenomegaly. The biopsy of inguinal lymphadenopathy showed a blast variant mantle cell lymphoma. Hence, chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) and rituximab therapy (r-CHOP) were initiated and he underwent six cycles of chemotherapy and four cycles of rituximab (protocol of 375 mg/m2 weekly for 4 weeks) with a good clinical and radiological response always keeping a normal renal function. Six months after the chemo and immunotherapy completion, the patient suffered epigastralgia and vomiting with balance sheet deterioration of renal function (creatinine at 680 µmol / l).
He was on examination hemodynamically and respiratory stable with a diuresis at 1.5 l / d. There was no peripheral lymphadenopathy.
Biology showed no fluid electrolyte disturbance, normochromic normocytic anemia at 9.1g / dl, and 24-hours proteinuria at 1.76g.
The tumor markers were negative as well as the immunological assessment, which included antinuclear, anti-glomerular basement membrane, and anti-neutrophil cytoplasmic antibodies. Abdominal ultrasound showed kidneys of normal size. There was no lymphadenopathy or hepatosplenomegaly on computed tomography.
The acute renal failure rapidly worsened (creatinine 996 then 1042 µmol / l) and remained unexplained indicating an urgent renal biopsy, which was performed within 72 h after admission. The biopsy showed a severe acute interstitial nephritis made of lymphocytic infiltrate with many nonnecrotizing granulomas (Figures 1&2). These findings were strongly suggestive of sarcoidosis. So, in the absence of recent medication and after ruling out other causes of granulomatous interstitial nephritis, sarcoidosis was the most likely diagnosis.
The assessment of sarcoidosis did not show extra renal involvement. Indeed, the dermatological examination did not find skin lesions, the ophthalmological examination was without abnormality, the thoracic-abdominal-pelvic scan did not show any signs of sarcoidosis, and serum calcium, vitamin D, and converting enzyme levels were normal.
Oral corticosteroid therapy was initiated at a dose of 1 mg/kg/day per os with a favorable outcome and significantly improved renal function (creatinine from 1042 to 570 µmol /l in 8 days and to 150 µmol /l in 15 days).
At follow-up 6 and 9 months later, renal function was stable with plasma creatinine around 120 µmol /l. He has not had a relapse of his lymphoma or other organ involvement of SLR.