Chromophobe Renal Carcinoma

 

Epidemiology:

    •  55y mean age
    • M=F

 

Common sites:

    •  

 

Gross features:

    •  solid
    • well-circumscribed
    • light tan or brown to mahogany
    • may have necrosis, calcifications
    • may have a central scar

 

Histologic features:

    • solid sheets arrangement
      • sometimes limited tubule formation
    • intersected by fibrous septa
      • often broad and hyalinized
      • may be thin and delicate
    • nonencapsulated
    • “classic” cell type:
      • large, polygonal
      • abundant pale or translucent, flocculent or finely reticulated pink or basophilic cytoplasm
        • entirely clear cytoplasm is not characteristic
      • prominent cell membranes
        • “cobble-stone” or “plant-like” appearance
      • tend to aggregate around fibrovascular septa
    • “eosinophilic” cell type:
      • smaller
      • arranged in small nests or intermingled with “classic” cells
      • cytoplasm less abundant, granular, more darkly eosinophilic
      • distinctive perinuclear halos (“invariably” seen)
    • some large cells with abundant clear to foamy “hydropic” cytoplasm
    • hyperchromatic nuclei
      • elongated, grooved
      • irregular nuclear membrane, “raisinoid”
      • round nuclei with focally wrinkled contours may be seen
      • binucleate cells always present
      • focal cytologic atypia with bizarre nuclei, may be prominent
    • very low mitotic activity (except in sarcomatoid areas)
    • distinction from oncocytoma may be difficult
    • may have sarcomatoid change (worse prognosis)

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Hale’s colloidal iron (stains acid mucopolysaccharides)
strong and diffuse
finely granular
cytoplasmic

May be focal, weak, or even absent in cases with predominantly eosinophilic cells 

 

Pancytokeratin

 

 

EMA

 

 

CK7

(accentuated at the cell membrane)

 

In oncocytoma, only scattered cells or small clumps of cells react

CAM 5.2/AE1

 

 

Parvalbumin

 

 

Vimentin (neg) (positive in sarcomatoid areas)

“Virtually always”

 

CD10 (neg)

 

 

HMWK (neg)

 

 

 

Molecular features:

    • multiple chromosome losses
    • extreme hypodiploidy

 

Other features:

    •  Better prognosis than conventional clear cell carcinoma
    • EM – numerous cytoplasmic microvesicles

 

References:

    •  Robbins 2005
    • Essentials of AP 2006
    • Sternberg 2004