A 20-year-old African American male presented with a history of
left flank pain and passing of light pink urine. Medical history included
sickle cell trait. Urine analysis was positive for
protein and blood. Metabolic profile,
autoantibody screen, and
complement levels were normal.
Hemoglobin electrophoresis revealed an 41.8% HbS diagnostic of
sickle cell trait.
Creatinine clearance was normal and
proteinuria was nonnephrotic. A noncontrast computed tomography (CT) scan showed left proximal
hydronephrosis. Urology follow-up was arranged and the differential included renal papillary
necrosis, or renal
cyst rupture. He presented 3 months later with sudden onset
left flank pain and gross
hematuria. Serum
creatinine was 1.8 mg/dL. Computed tomography scan with contrast revealed innumerable lung lesions, an enlarged heterogenously enhancing left kidney, and retroperitoneal
adenopathy. Ultrasound revealed an obstructed left collecting system and a 14-cm enlarged left kidney with no discrete mass. Testicular markers/ultrasound, upper/lower endoscopies were normal. Lung biopsy revealed poorly differentiated
adenocarcinoma positive for
cytokeratin 7. Renal,
sarcoma, and gastrointestinal markers were negative. By exclusion, it appeared that the patient had a
carcinoma of unknown primary. However, with the clinical and personal history, a diagnosis of renal
medullary carcinoma (RMC) was made. RMC is a rare and highly malignant
tumor that should always be included in the differential of a patient with
sickle cell disorder and
hematuria. Renal biopsy typically fails to sample the renal medulla and radiologic findings might not raise the suspicion of a renal
tumor. Thus, clinical suspicion must always be high in order to preserve the patient's only chance of prolonged survival.