A 49-year-old female with a history of nephrolithiasis
and renal cysts underwent routine imaging and was found to have an incidental
left renal mass.
She was clinically asymptomatic and denied any
hematuria, abdominal pain or any other systemic symptoms.
A renal ultrasound showed an isoechoic lesion in the
lateral aspect of the left interpolar region measuring 2.5 cm × 2.5 cm,
consistent with a solid renal mass. MRI of the abdomen confirmed a well-defined
lesion measuring 2.9 cm × 2 cm in the mid-lower left kidney. The dynamic
study indicated enhancement with a differential diagnosis of renal cell
carcinoma with hemorrhagic component.
Figure 1. Noncontrast CT of the abdomen demonstrates a focal
mass (arrow) in the lateral aspect of the mid-level of the left kidney. This
homogenous focal mass demonstrates slightly higher attenuation, though not
significantly, measuring approximately 28 Hounsfield units (HU). The remaining
uninvolved portions of the kidney demonstrate approximately 22 HU attenuation.
Images courtesy of M. Ghesani, MD,
reprinted with permission
She underwent left radical nephrectomy. The gross
pathology specimen showed a 2.8 cm × 2.4 cm × 2 cm,
well-circumscribed, golden-yellow, round mass. The mass was unifocal, and
histological analysis showed a 2.8-cm papillary renal cell carcinoma showing
type 1 tubulopapillary pattern.
The surgical margins were free of tumor with no evidence
of lymphatic or venous invasion. She was surgically staged I. She did well
postoperatively with no complications. Her routine follow-up scans showed no
evidence of recurrent disease.
Figure 2. Ultrasound of the kidney demonstrates a probable sold
left renal mass, which measured approximately 2.5 cm × 2.5 cm.
Renal cell carcinoma (RCC) includes 80% to 85% of all
primary renal neoplasms. They originate primarily from the renal cortex.
Primary renal medullary carcinoma is a rare form of RCC
seen in patients with sickle cell trait. An estimated 61,000 cases of RCC were
diagnosed in the United States in 2011, with about 13,000 deaths.
The prognosis is dependent upon the stage at
presentation, with 5-year survival varying from 90% for localized disease to
less than 10% for metastatic disease.
Different histological subtypes of RCC have been
identified, and they differ in their prognosis and genetic alterations.
Overall, clear cell subtype accounts for 75% to 85% of all renal cell
carcinomas. The next most common is papillary subtype (10% to 15%), followed by
chromophobic (5% to 10%), oncocytic and collecting duct tumors.
In a 2006 study in RadioGraphics, Prasad
and colleagues described various radiographic findings in different
histological subtypes. Clear cell RCC are hypervascular secondary to
inactivation of von Hippel-Lindau gene with subsequent activation of various
growth factor genes involved in angiogenesis and metastasis. The degree of
enhancement seen on a contrast study can be useful in distinguishing clear cell
RCC from nonclear variants.
These tumors also can demonstrate areas of hemorrhage
and necrosis that can be visible on the imaging studies. The papillary variant,
however, is more homogeneous and hypovascular than the clear cell. These tumors
frequently are multifocal and bilateral, and they commonly present as small
tumors. Rarely, macroscopic fat deposits on CT have been described in papillary
tumors. These are related to the presence of foamy macrophages with cholesterol
necrosis, a pathological finding very suggestive of papillary cell carcinoma.
Chromophobe variant and oncocytomas originate from the
intercalated cells of the collecting system, and they demonstrate similar
genetic alteration and imaging features. These are hyperechoic on
ultrasonography and appear homogeneous on contrast enhanced studies. They often
are well circumscribed and are relatively hypovascular. Collecting duct tumors
and renal medullary carcinoma are aggressive tumors and present with
infiltrating features on imaging. These usually are heterogeneous with areas of
hemorrhage, necrosis and calcifications.
Papillary RCC is readily distinguished from clear cell
RCC based on microscopic findings. Papillary RCC is characterized by a complex
papillary architecture and is subtyped into two groups depending on the
In type 1, a single layer of cells with scanty cytoplasm
lines the papillae. Additional, the stroma may be infiltrated by neutrophils or
foamy macrophages, and psammoma bodies are commonly present. In type 2, a
pseudostratified epithelium composed of cells with abundant acidophilic
cytoplasm line the papillae.
A low-power hematoxylin and eosin (H&E) slide demonstrates a
well-circumscribed tumor with a complex tubulopapillary pattern and compressed
surrounding renal parenchyma (Figure 4a). A high-power H&E slide depicts
papillae lined by a single layer of cells with scanty cytoplasm (Figure
Regardless of morphologic appearance, the clinical
outcome is similar. Although clear cell RCC may have a papillary architecture,
the cells should contain cytoplasm in contrast to the acidophilic cytoplasm
seen in papillary RCC.
Papillary RCC also can be distinguished from clear cell
RCC based on cytogenetics. Papillary RCC present with trisomies of chromosomes
3q, 7, 8, 12, 16, 17 and 20, and loss of Y chromosome, and it does not show
loss of 3p, which often is present in clear cell RCC.
Thus, these renal cell carcinomas include several
distinct subtypes characterized by different radiological and pathological
findings. With the development of new targeted agents, it also is important to
recognize these different subtypes, as these can show different response to
treatment. For example, sorafenib (Nexavar, Bayer HealthCare) and sunitinib
(Sutent, Pfizer) are shown to be active in clear cell carcinoma. Everolimus
(Afinitor, Novartis) and a new multitargeted tyrosine kinase inhibitor,
cabozantinib (Exelixis), have shown to have some activity in papillary tumors.
The radiological features can provide important information in the pretreatment
diagnosis of these tumors.
- Lesavre A. AJR Am J Roentgenol. 2003;181:143-145.
- Prasad SR. Radiographics. 2006;26:1795-1806.
- Rosai J. Rosai and Ackerman’s Surgical Pathology.
10th ed. St. Louis: Mosby; 2011.
- Siegel R. CA Cancer J Clin. 2011;61:212-236.
For more information:
- Munir Ghesani, MD, is an attending radiologist
at St. Luke’s-Roosevelt Hospital Center and Beth Israel Medical Center, an
associate clinical professor of radiology at Columbia University College of
Physicians and Surgeons, and a HemOnc Today section editor.
Matthew Teng, MD, is a resident in radiology at St Luke’s-Roosevelt
Hospital Center. Sumit Talwar, MD, is a fellow in hematology/oncology at St.
Luke’s-Roosevelt Hospital Center. Darren Buonocore, MD, is a postdoctoral
residency fellow in pathology at St. Luke’s-Roosevelt Hospital Center.
Peerapod Chiowanich, MD, is an assistant attending radiologist at St.
Luke’s-Roosevelt Hospital Center. Disclosure: Drs. Ghesani, Teng,
Talwar, Buonocore and Chiowanich report no relevant financial disclosures.