Medullary carcinoma of the kidney
12 year old African-American male with abdominal mass
Publication Date: 2004-11-05
12 year old African-American male with abdominal mass.
Renal medullary carcinoma is a recently described, aggressive kidney tumor that has been called "The seventh sickle cell nephropathy". It classically occurs in young, black patients, the majority of whom have sickle cell trait. Sickled erythrocytes have been demonstrated within the tumor or adjacent tissues on light microscopy in many patients in whom the sickle cell status has been unknown.
Renal medullary carcinoma has a characteristic appearance on CT scans. The tumor arises deep within the renal medulla and infiltrates the renal pelvis and sinus. The collecting system of the kidney is compressed rather than obstructed and the reniform outline of the kidney is preserved. The tumor enhances poorly with IV contrast. At the time of diagnosis regional lymphadenopathy, direct invasion of surrounding organs and tissues, and distant metastases to the liver and lung parenchyma are also commonly seen. Metastatic disease to bone has been reported in a few cases.
In children with a primary renal neoplasm and bone metastases, the main differential diagnosis is a clear cell sarcoma, as classical Wilms' tumor rarely metastasises to bone. Medullary renal carcinoma is a rare tumor that should be suspected in young patients of African ancestry who present with the clinical features and CT appearances described. Whole body scintigraphy should be performed prior to the commencement of therapy in order to determine the full extent of disease.
Tumors of the kidney are the fifth most common pediatric malignancies in the United States. More than 80% of these are Wilms' tumors, with most occurring in children <5 years of age. Most of these patients present with a painless abdominal mass. In contrast, renal cell carcinoma, the most common renal malignancy in adults, represents only 1.8 to 6.3% of malignant pediatric renal tumors; patients generally present with painless microscopic hematuria. Wilms' tumor and renal cell carcinoma generally grow by expansion, rather than infiltration, and involve the cortex of the kidney, rather than the medulla. Tumors that invade the renal pelvis and medulla are extremely rare, particularly in children.
In contrast to the rarity of pediatric renal tumors, sickle cell disease and sickle cell trait are very common in the United States. A frequent manifestation of these is nephropathy. In 1974, Berman described six nephropathies seen in patients with sickle cell disease or trait. These include 1) gross hematuria, 2) papillary necrosis, 3) nephrotic syndrome, 4) renal infarction, 5) isosthenuria, and 6) pyelonephritis. These sickle cell nephropathies can present clinically as hematuria, proteinuria, renal insufficiency, concentrating defects, or hypertension. Patients with sickle cell trait have a higher incidence of gross hematuria than patients with sickle cell disease. The gross hematuria can be painless and is thought to arise from bleeding immediately beneath the renal pelvic epithelium or as a result of papillary necrosis. It involves the left kidney in >80% of patients.
Recently, a new entity, renal medullary carcinoma, suggested to be the seventh sickle cell nephropathy, has been described by Davis et al at the Armed Forces Institute of Pathology. They reviewed 55 cases of "renal pelvic carcinoma" diagnosed over a 22-year period. Two distinct tumor types emerged. Twenty-one of the fifty-five cases were typical transitional cell carcinoma. The remaining thirty-four cases were highly aggressive, infiltrating, poorly circumscribed, renal tumors occurring primarily in young black patients with sickle trait. These tumors occurred in patients ranging in age from 11 to 39 years. Macroscopically, the tumors occupied primarily the renal medulla and invaded the calyces; satellite lesions were often present on the renal cortex. Most (23 of 31) involved the right kidney and all demonstrated lymphatic and/or vascular invasion. Histologically, the tumors demonstrated a distinctive reticular growth pattern with some transitions to a more adenoid cystic appearance. Acute inflammation and stromal proliferation was present. Nine patients had known sickle trait; one patient had SC disease. The sickle cell disease status of the remaining patients was unknown, but all patients had sickled cells identified microscopically within the tumor or adjacent renal parenchyma.
- Warren KE, Gidvani-Diaz V, Duval-Arnould B. Renal medullary carcinoma in an adolescent with sickle cell trait. Pediatrics. 1999 Feb;103(2):E22.