Renal

Question 1

Answer 1

Cystic nephroma

• multilocular cyst with a background of ovarian-type stroma: fairly blue, cellular, spindly, and estrogen and progesterone receptor positive

Question 2

Answer 2

simple cyst

• a dilated tubule and will have a low cuboidal or flattened pink epithelial lining

Question 3

Answer 3

multilocular cystic renal neoplasm of low malignant potential

• renal neoplasm of low malignant potential. The cyst lining and fibrovascular septa (arrowhead) are composed of clear cells with small dark nuclei (arrow)

Question 4

Answer 4

multilocular cystic renal neoplasm of low malignant potential

Question 5

Angiomyolipoma Features

Answer 5

• Large, tangled, tortuous, thick-walled, hyalinized vessels
• Smooth muscle cells (pink to clear and spindly) that seem to spin off of, or be continuous with, the vessel walls
• Mature fat cells without atypia or lipoblasts
• Pushing borders but not encapsulated HMB-45 and Melan-A positive (NOT S100)

Question 6

Answer 6

Angiomyolipoma. This example does not show the fatty component, but the prominent vessels (V) and smooth muscle components here are classic. In angiomyolipoma, the spindle cells seem to merge with, or spin off from, the thick-walled vessels (arrow).

Question 7

Answer 7

Angiomyolipoma

Question 8

Answer 8

Angiomyolipoma

Question 9

Answer 9

Angiomyolipoma

Question 10

Answer 10

Angiomyolipoma

Question 12

Mixed Epithelial and Stromal Tumor (MEST) Features

Answer 12

a population of cytologically benign tubules of varying shapes and sizes set in a background of bland spindled stroma, which may consist of smooth muscle, fibroblasts, or myofibroblasts.

Question 13

Answer 13

MEST

Question 14

Clear Cell Renal Cell Carcinoma Features

Answer 14

• A netlike array of delicate capillaries, dividing cells into packets (“acinar” pattern)
• Clear cytoplasm, at least focally if not diffusely
• Delicate, distinct cell membranes
• Lack of desmoplasia (although sclerosis of burned-out tumor is common)

Question 15

ISUP nucleolar grade I-IV

Answer 15

• Grade I: nuclei resemble lymphocytes, no nucleoli
• Grade II: nuclei still small, +/− tiny nucleoli, but with open chromatin
• Grade III: easily recognizable nucleoli, larger nuclei
• Grade IV: pleomorphic and hyperchromatic nuclei with big nucleoli

Question 16

Answer 16

Clear cell renal cell carcinoma. The tumor is composed of packets of clear cells, divided by delicate fibrovascular septa (arrow). These septa are characteristic of renal cell carcinoma and are seen even in high-grade or metastatic tumors. The nuclei in this example are enlarged, but nucleoli are visible only at high power, consistent with ISUP grade II.

Question 17

Chromophobe Renal Cell Carcinoma Features

Answer 17

• Distinct cell membranes that give the tumor a three-dimensional texture, like alligator skin or plant cells
• Cells of varying sizes and shapes
• Pink, granular, wispy cytoplasm, often with a perinuclear clearing
• Nuclei that vary in size and shape and are crinkly, like koilocytes
• Can transform to sarcomatoid morphology

Question 18

Clear Cell Papillary (or Tubulopapillary) Renal Cell Carcinoma Features

Answer 18

• Clear cells with small, dense, dark nuclei, often oriented with the nucleus on the luminal surface, and the cytoplasm toward the base (“upside down”
• Cells are arranged on delicate fibrovascular cores or in small closely packed tubules.
• May show cystic degeneration.
• Small tumors, well circumscribed, and often encapsulated.

Question 19

Answer 19

Chromophobe renal cell carcinoma. (a) Low power view of chromophobe, showing packets of cells with clear-to-pink cytoplasm, perinuclear halos, and occasional binucleate cells (arrow). The cell membranes are distinct, giving the tumor a cobblestone or alligator skin texture. (b) High power view of a chromophobe carcinoma, eosinophilic variant. Although the granular pink cytoplasm resembles an oncocytoma (see Figure 13.12), the nuclei are distinctly koilocytic, with crinkly outlines and perinuclear halos (arrow). In addition, the fine cellular membranes are preserved (arrowhead).

Question 20

Answer 20

Clear cell papillary renal cell carcinoma. There are clear cells arranged on fibrovascular cores, creating a papillary pattern. The small dark nuclei are classically lined up at the luminal surface of the clear cells, rather than at the base (arrows).

Question 21

Answer 21

Mucinous tubular and spindle cell carcinoma. In an overall pale tumor, the nuclei are small and euchromatic and arranged in long tubules and areas of spindling.

Question 22

Mucinous Tubular and Spindle Cell Carcinoma Features

Answer 22

• Long arrays of narrow tubules, which may remind you of renal medulla at low power
• Clear cells with indistinct cell boundaries that may fuse into spindle cell areas.
• Nuclei are small, round, and pale, sometimes with pinpoint nucleoli.

Question 23

Xp11 translocation RCC

Answer 23

Typically a tumor with plump clear cells, large nuclei, papillary architecture, and psammoma bodies.

Question 24

t(6;11) RCC

Answer 24

The unique feature of this tumor is a dual cell population, with nests of large clear or granular pink cells interspersed with aggregates of small compact cells which can be mistaken for lymphocytes at low power

Question 25

Answer 25

t(6;11) carcinoma. There are large clear or granular pink cells (arrowheads) interspersed with aggregates of small compact cells (arrow).

Question 26

Answer 26

Oncocytoma. The nuclei are typically very round, uniform in size, and evenly spaced. Nucleoli may be seen, but there are no perinuclear halos. The cytoplasm is pink and granular, similar to oncocytic neoplasms elsewhere in the body.

Question 27

Answer 27

Papillary renal cell carcinoma, Type 1. The tumor cells are pink, not clear, and range from cuboidal to columnar (arrowhead). This tumor may grow as solid sheets and tubules, but finding papillary structures with central cores packed with foamy histiocytes (arrow) is diagnostic. Although the tumor in this example is of low nuclear grade, the cells have a relatively high N/C ratio, and therefore this would be somewhat blue on low power.

Question 28

Answer 28

Tubulocystic carcinoma. This tumor consists of a spongy collection of dilated tubules lined by plump pink apocrine-looking cells with round nuclei.

Question 29

Answer 29

Metanephric adenoma. This benign tumor is the bluest of them all because of the very high N/C ratio of the cells. Here you can see tiny primitive blue tubules on the left, adjacent to the normal kidney on the right.

Question 30

• Nephrogenic rests
• Blastema
• Anaplasia

Answer 30

• Nephrogenic rests: abnormally persistent foci of embryonal cells (small, round, and blue) that may develop into Wilms tumor, although most do not
• Blastema: sheets of undifferentiated embryonal cells in a Wilms tumor or the prototypical small round blue cells
• Anaplasia: unfavorable histology in a Wilms tumor, defined by large, hyperchromatic nuclei and abnormal mitotic figures (such as tripolar)