Case 150 - Discussion

Uploaded: 2007-11-20, Updated: 2007-11-20

 
Renal Cell Carcinoma, Chromophobe Cell Type
 

The Key Features

  • Two types of cells: classic and eosinophilic;

  • "Plant cells", wrinkled raisin nuclei;

  • Perinuclear halo, abundant cytoplasmic vesicles, especially perinuclear region;

  • CK7+, CD117+, colloid iron+;

  • Vimentin-, CD10-.

CLINICAL FEATURES
 
  • 5 percent of renal neoplasms
GROSS FINDINGS
 
  • Well circumscribed and solitary.
  • The cut surfaces are typically pale yellow, tan, or brown.
  • Hemorrhage, necrosis, scarring, calcification and ossification may be seen.
MICROSCOPIC FINDINGS
 
  • Mixtures of classic and the eosinophilic types. The tumor cells are arranged in broad trabeculae and solid sheets with occasional tubule formation. Psammoma bodies may be present.
  • The cells of the classic type are usually arranged along septa. They have well-defined borders and abundant, finely reticular, translucent to pale acidophilic cytoplasm. The pale acidophilic appearance is due to the presence of abundant microvesicles distending the cytoplasm. The cells of the eosinophilic type are usually in the center with a high similarity to the oncocytes.
  • Perinuclear halo: the cytoplasmic microvesicles often concentrate around the nucleus, producing a distinctive appearance of perinuclear halo. This is an important distinguishing feature from oncocytoma.
  • "Plant-like" cells: frequently, the cytoplasmic organelles are pushed to the periphery, producing a more intense peripheral acidophilia.
  • The nuclei are slightly pleomorphic with granular chromatin and scattered nucleoli. In the classic cell type, the nuclear membrane is often irregular, resulting in a "raisinoid" appearance. Binucleate cells are often present.
  • May undergo sarcomatoid transformation.
DIFFERENTIAL DIAGNOSES
 

 

Oncocytoma

Chromophobe RCC

Gross

Mahogany brown +/- central scar

Pale tan-brown, +/- central necrosis

Architecture

Closely packed nests (periphery) and nests in loose hypocellular stroma; no trabeculae/sheets

Closely packed nests; +/-broad trabeculae/sheets

Cell

Uniform, limited atypia

Classic and eosinophic cells, more atypia

Cytoplasm

Granular, acidophilic

Granular, acidophilic with perinuclear halos

Nuclei

Uniform, round, degenerative pleomorphism

More pleomorphism, "raisinoid"

Mitoses

None or rare

Occasional

Colloidal iron

Focal positivity, in the lumen.

Strongly diffuse positivity

CK

Positive,CK7-scattered strong positive

Positive,CK7-diffusely strong positive

Vimentin

Negative

Negative

Ultrastructure

Numerous mitochondria with lamellar cristae;

no microvesicles

Numerous mitochondria with tubulovesicular cristae; interspersed microvesicles

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS
 
  • Hale colloidal iron stain: the microvesicles are stained with a diffuse, intense, and reticular pattern.
  • Positive: CK7 and 14, CD117, EMA, RCC (50%), soybean agglutinin, parvalbumin and beta-defensin-1 and carbonic anhydrase C.
  • Negative:  CK-HMW,  vimentin, CD10.
ELECTRON MICROSCOPIC FINDINGS
 
  • Abundant cytoplasmic microvesicles concentrated adjacent to and surrounding the nucleus;
  • Mitochondria exist more peripherally in the classic form.
CYTOGENETIC STUDIES
 
  • Loss of chromosome 1, 2, 6, 10,13, 17, and 21.
TREATMENT AND PROGNOSIS
 
  • More favorable than the conventional clear cell RCC.
REFERENCES
 
  • Rosai and Ackerman's Surgical Pathology, 9th edition;
  • AFIP, tumor of the kidney, bladder and related urinary structures, series 4;