A renal

oncocytoma An oncocytoma is a tumor made up of oncocytes, epithelial cell (biology), cells characterized by an excessive amount of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. The cells and the tumor that they compose are often be ...

is a

tumour A neoplasm () is a type of abnormal and excessive growth of tissue (biology), tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tiss ...

of the

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

made up of oncocytes,

epithelial cells Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

with an excess amount of

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

Signs and symptoms

Renal oncocytomas are often asymptomatic and are frequently discovered by chance on a CT or

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

of the abdomen. Possible signs and symptoms of a renal oncocytoma include blood in the urine, flank pain, and an abdominal mass.

Pathophysiology

Renal oncocytoma is thought to arise from the intercalated cells of

collecting duct The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis. The collecting duct participates in electrolyte and fluid balance through rea ...

s of the kidney. It represent 5% to 15% of surgically resected

renal In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and right in the retrop ...

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s. Ultrastructurally, the eosinophilic cells have numerous

Histologic appearance

An oncocytoma is an

epithelial Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

tumor composed of oncocytes, large eosinophilic cells having small, round, benign-appearing nuclei with large

nucleoli The nucleolus (; : nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis. The nucleolus also participates in the formation of signal recognition particles and plays a ro ...

and excessive amounts of

Diagnosis

In gross appearance, the tumors are tan or mahogany brown, well circumscribed and contain a central scar. They may achieve a large size (up to 12 cm in diameter). The main

differential diagnosis In healthcare, a differential diagnosis (DDx) is a method of analysis that distinguishes a particular disease or condition from others that present with similar clinical features. Differential diagnostic procedures are used by clinicians to di ...

of renal oncocytoma is ''chromophobe renal cell carcinoma oncocytic variant'', which like the renal oncocytoma has eosinophilic cytoplasm, but has perinuclear clearing and, typically, some degree of nuclear atypia.

Immunohistochemical profile

Cytokeratin Cytokeratins are keratin proteins found in the intracytoplasmic cytoskeleton of epithelial tissue. They are an important component of intermediate filaments, which help cells resist mechanical stress. Expression of these cytokeratins within ep ...

AE1/AE3 + *

Vimentin Vimentin is a structural protein that in humans is encoded by the ''VIM'' gene. Its name comes from the Latin ''vimentum'' which refers to an array of flexible rods. Vimentin is a Intermediate filament#Type III, type III intermediate filamen ...

- * EMA + *

CD10 Neprilysin (; also known as membrane metallo-endopeptidase (MME), neutral endopeptidase (NEP), cluster of differentiation 10 (CD10) and common acute lymphoblastic leukemia antigen (CALLA)) is an enzyme that in humans is encoded by the ''MME'' ge ...

+/- * CK7 +/- parcellaire * CK20 - * CK19 - * AMACR ( Racemase) - * S100 + *c-kit (

CD117 Proto-oncogene c-KIT is the gene encoding the receptor tyrosine kinase protein known as tyrosine-protein kinase KIT, CD117 ( cluster of differentiation 117) or mast/stem cell growth factor receptor (SCFR). Multiple transcript variants encoding d ...

) + * Cadherin-E + * TFE3 - * CAM5.2 +

Treatment

Renal oncocytoma is considered

benign Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...

, cured by

nephrectomy A nephrectomy is the surgical removal of a kidney, performed to treat a number of kidney diseases including kidney cancer. It is also done to remove a normal healthy kidney from a living or deceased donor, which is part of a kidney transplant pro ...

. There are some familial cases in which these tumors are multicentric rather than solitary.Robbins pathology, page 1015 However, they may be resected to exclude a malignant tumor, e.g. renal cell carcinoma.

Prognosis

The overall

five-year survival rate The five-year survival rate is a type of survival rate for estimating the prognosis of a particular disease, normally calculated from the point of diagnosis. Lead time bias from earlier diagnosis can affect interpretation of the five-year surv ...

has been estimated to be 63%, with 100% disease-specific survival.

Additional images

Image:Renal oncocytoma2.jpg,

Micrograph A micrograph is an image, captured photographically or digitally, taken through a microscope or similar device to show a magnify, magnified image of an object. This is opposed to a macrograph or photomacrograph, an image which is also taken ...

of a renal oncocytoma.

H&E stain Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin–eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diag ...

. Image:Renal oncocytoma4.jpg, Micrograph of a renal oncocytoma. H&E stain. Image:Renal oncocytoma (1).jpg, Micrograph of a renal oncocytoma. H&E stain. Image:Renal oncocytoma (2).jpg, Micrograph of a renal oncocytoma. H&E stain. Image:Renal oncocytoma (3).jpg, Micrograph of a renal oncocytoma. H&E stain. Image:Chromophobe renal cell carcinoma, eosinophilic variant - high mag.jpg, Micrograph of ''chromophobe RCC oncocytic variant'', the main differential diagnosis of renal oncocytoma.

References

External links

{{DEFAULTSORT:Renal Oncocytoma Benign renal neoplasms