Bf. Skinnider et Ec. Jones, Renal oncocytoma and chromophobe renal cell carcinoma - A comparison of colloidal iron staining and electron microscopy, AM J CLIN P, 111(6), 1999, pp. 796-803
Citations number
26
Categorie Soggetti
Research/Laboratory Medicine & Medical Tecnology","Medical Research Diagnosis & Treatment
Chromophobe renal cell carcinoma (RCC) is characterized by diffuse cytoplas
mic staining with Hale colloidal iron (HCI) and the presence of numerous mi
crovesicles. The eosinophilic variant morphologically may resemble renal on
cocytoma. The latter commonly shows focal cytoplasmic HCI reactivity, but m
icrovesicles have not been previously reported. We examined 19 chromophobe
RCCs and 28 oncocytomas for their HCI staining patterns. Electron microscop
y was performed on 13 chromophobe RCCs and 10 oncocytomas. In all cases of
chromophobe RCC, more than 75% of cells showed a diffuse cytoplasmic HCI po
sitivity, whereas a variable proportion of cells in 20 oncocytomas showed f
ocal cytoplasmic staining in a perimembranous, apical, or perinuclear patte
rn. Ultrastructurally, chromophobe RCCs contained abundant microvesicles wi
th varying numbers of mitochondria, whereas all oncocytomas contained abund
ant mitochondria with focal collections of microvesicles. The microvesicles
, in perimembranous, apical, or perinuclear clusters or singly scattered th
roughout the cytoplasm, were morphologically indistinguishable from those i
n chromophobe RCCs. In most cases, the microvesicle location and HCI staini
ng pattern correlated. Chromophobe RCC and oncocytoma have distinctive morp
hologic features that usually allow their recognition. In difficult cases,
HCI staining and electron microscopy may help, but the presence of HCI posi
tivity or microvesicles in an eosinophilic renal tumor does not rule out on
cocytoma.