Renal Neoplasia

Comprehensive vocabulary flashcards reviewing benign and malignant renal neoplasms, including oncocytoma, angiomyolipoma, and the clear cell, papillary, and chromophobe variants of renal cell carcinoma.

Oncocytoma

A benign renal tumor representing $3\text{ to }7\%$ or $6\text{ to }9\%$ of renal tumors; grossly single, well circumscribed, tan to mahogany brown with a central scar in about one-third of cases, and histologically composed of cells with round nuclei and abundant, brightly eosinophilic granular cytoplasm packed with mitochondria.

Intercalated cells of collecting ducts

The specific tubular epithelial cell type from which both oncocytomas and chromophobe renal cell carcinomas are thought to arise.

Angiomyolipoma

A benign renal lesion belonging to the PEComa family composed of poorly formed thick-walled blood vessels, smooth muscle cells, and adipocyte-like cells; it is prone to spontaneous hemorrhage and strongly associated with tuberous sclerosis complex.

PEComas

A family of tumors demonstrating perivascular epithelioid cell differentiation that are thought to be derived from pericytes, to which angiomyolipomas belong.

Tuberous sclerosis complex

A genetic condition caused by loss of function of $TSC1$ or $TSC2$; about $25\text{ to }50\%$ of affected patients have renal angiomyolipomas, and it is additionally associated with cardiac rhabdomyomas, cerebral cortical tubers, and subependymal giant cell astrocytomas (SEGA).

Renal cell carcinoma (RCC)

Malignancies arising from the renal tubular epithelium that account for approximately $80\text{ to }85\%$ of primary renal malignancies, with major risk factors including smoking, cadmium exposure, and acquired cystic disease of the kidney from long-term hemodialysis.

Classic triad of renal cell carcinoma

The clinical presentation consisting of costovertebral pain, a palpable mass, and hematuria, which is seen in its entirety in less than $10\%$ of patients.

Inferior vena cava syndrome

A complication caused by renal cell carcinoma invading through the renal vein into the inferior vena cava up toward the heart, presenting with manifestations such as lower extremity edema and ascites.

Clear cell renal cell carcinoma

The most common primary renal cell carcinoma variant, arising from the proximal tubule; characterized grossly as a bright yellow cortical mass due to high lipid content, and histologically by nests of cells with optically clear cytoplasm separated by delicate fibrovascular septa.

Von Hippel-Lindau (VHL) syndrome

An autosomal dominant disorder occurring in $1\text{ in }36{,}000$ individuals characterized by hemangioblastomas of the cerebellum and retina, hundreds of renal cysts, and a $40\text{ to }60\%$ incidence of clear cell renal cell carcinoma.

VHL gene

A tumor suppressor gene located on the short arm of chromosome $3$ ($3p$) whose sequences are lost in about $98\%$ of clear cell renal cell carcinomas; it normally mediates oxygen-dependent degradation of hypoxia-inducible factors.

Hypoxia-inducible factors (HIFs)

Transcription factors (such as HIF-1$\alpha$) that accumulate and translocate to the nucleus upon loss of functional VHL protein, driving the upregulation of erythropoietin (EPO), vascular endothelial growth factor (VEGF), and alterations in glucose metabolism.

Papillary renal cell carcinoma

A renal malignancy accounting for about $15\%$ of primary renal cell carcinomas that arises from the proximal and distal convoluted tubules; it frequently shows trisomy of chromosome $7$ and often presents as multifocal and bilateral cortical tumors.

MET proto-oncogene

A gene located on chromosome $7$ that encodes a tyrosine kinase receptor for hepatocyte growth factor; its alteration is implicated in the pathogenesis of papillary renal cell carcinoma.

Type 1 papillary renal cell carcinoma

A subtype of papillary renal cell carcinoma characterized histologically by a single layer of small cells with low nuclear grade, presenting at a lower stage with a better prognosis, and displaying altered MET function in about $80\%$ of cases.

Type 2 papillary renal cell carcinoma

An aggressive subtype of papillary renal cell carcinoma characterized histologically by larger cells, pseudostratification, and higher grade nuclei, presenting at a higher stage with a worse prognosis and less frequent MET alterations.

Interstitial foam cells

Lipid-laden histiocytic cells typically found within the papillae cores of papillary renal cell carcinomas.

Chromophobe renal cell carcinoma

The rarest of the three main primary renal cell carcinomas, carrying an excellent prognosis; it is characterized by multiple chromosome losses with extreme hypodiploidy, and grossly appears brown to yellow-tan with occasional central scarring.

Vegetable wall appearance

A histologic feature typical of chromophobe renal cell carcinoma where prominent, thickened cell membranes and surrounding cytoplasmic clearing mimic plant cells viewed under microscopy, often accompanied by perinuclear halos.