Campbell Benign Renal Tumors 2021

Question 1

ADPKD

Answer 1

Inherited renal cystic disease
Mutation of PKD1 and PKD on short arm chromosome 16
PKD1 and 2: mechanosensor to flow of urine, regulates intracellular Ca –> mutation –> decreased intracellular Ca –> amplified cAMP –> upregulate effector –> cystic epithelial histology

Diagnosis: At least 2 unilateral or bilateral renal cysts before age 30;
At least 2 cysts in each kidney between ages 30-59, 4 cysts in each kidney 60 years and older

Question 2

Acquired cystic kidney disease (ACKD)

Answer 2

7% develop RCC after 10 years of dialysis

Cysts arise from PCT (as in clear cell) unlike ADPKD which arise from DCT

Question 3

Simple cysts are characterized on ultrasound by:

Answer 3

Smooth walls
Sharp outlines
Absence of internal echoes

Question 4

Hallmark of simple cyst disease on CT and MRI:

Answer 4

ABSENCE OF ENHANCEMENT

Question 5

Bosniak I

Answer 5

Simple cyst
Hairline thin wall, no septa, calcifications, solid components
No enhancement

Inc. of malignancy: 1.7%
TX: None

Question 6

Bosniak II

Answer 6

Few hairline septa, fine calcifications
Slightly thickened calcifications
Uniformly high-attenuation lesions <3cm
No enhancement

Inc. of malignancy: 18.5%
TX: None

Question 7

Bosniak IIF

Answer 7

Includes intrarenal non-enhancing high-attenuation lesions >=3cm

Inc. of malignancy: 18.5%
F = Follow-up
TX: Repeat imaging to assess stability of size and radiographic characteristics

Question 8

Bosniak III

Answer 8

Indeterminate cystic masses with thickened irregular or smooth walls with MEASURABLE CONTRAST ENHANCEMENT

Inc. of malignancy: 33%
TX: Active surveillance, excision, ablation

Question 9

Bosniak IV

Answer 9

Malignant cystic masses, all of category III criteria
Containing soft-tissue enhancing components

Inc. of malignancy: 92.5%
TX: Excision or ablation

Question 10

MOST COMMON benign enhancing renal mass

Answer 10

Oncocytoma

Question 11

MOST COMMON benign renal tumor

Answer 11

Renal cyst disease

Question 12

Oncocytoma

Answer 12

Overlapping features with eosinophilic chromophobe RCC/SHDD RCC, and papillary RCC

Associated with perirenal fat and renal vein invasion BUT should NOT BE INTERPRETED as aggressive

CK-7 rarely positive in oncocytoma but diffusely positive in chromophobe RCC

Genetic predisposition: Birt-Hogg-Dube syndrome and renal oncocytosis

Imaging: hypervascularity and central scar on axial (but not definitive)

TX:
Usually diagnosed post-op
If renal biopsy done: active surveillance - may have favorable results
Nephron-sparing when technically feasible

Question 13

Birt-Hogg-Dube (BHD) syndrome

Answer 13

Autosomal dominant
Mutations in the folliculin gene chromosome 17
Pulmonary cysts (70-84%)
Spontaneous pneumothoraces (25%)
Cutaneous fibrofolliculomas (>90%)
Chromophobe RCC (12-34%)

Question 14

Angiomyolipoma, epidemiology and imaging

Answer 14

Benign, dysmorphic blood vessels + smooth muscle + adipose tissue

Associated with TSC and LAM

Female predisposition
Peak 4th-5th decade of life

55-90% earlier presentation in TSC

Imaging: intralesional fat (-15 to -20 HU) on PLAIN CT is DIAGNOSTIC

MRI: India ink artifact (dark boundary on in-phase/opposed-phase imaging)

Question 15

AML associated genetic syndromes (2)

Answer 15

Tuberous sclerosis complex (TSC)

Lymphangioleiomyomatosis (LAM)

Question 16

AMLs ____ in size are expected to be asymptomatic, therefore ____ is an option.

Intralesional aneurysm ___ in diameter was predictive of ___.

Answer 16

< 4 cm in size
Active surveillance

Aneurysm > 5 mm
Subsequent hemorrhage

Question 17

Selective arterial embolization for AML

Answer 17

Reserved for the management of acute hemorrhage

obligates the patient to continued surveillance (based on recurrence risk), whereas surgery is curative in most sporadic AML cases

Question 18

___ is approved by the USFDA for treatment of AML in the setting of ___.

For larger, multifocal AMLs.

Answer 18

Everolimus
TSC

** Phase III trial: 42% response rate (at least 50% reduction in volume); only 14.3% progression in 4 years, no patient required embolization or bleeding.

Question 19

Papillary adenoma definition

Answer 19

In 2004 the World Health Organization defined papillary adenoma as a low-grade (grade 1–2), well- circumscribed cortical lesion measuring less than 0.5 cm .

Question 20

Metanephric adenoma

Answer 20

Flank pain, gross hematuria, palpable mass, polycythemia

NO necrosis, atypia or mitotic figures
POSITIVE for WT1 and CD57
NEGATIVE for AMACR (positive in papillary RCC)

Imaging: enhancement uniformly less than renal parenchyma: in contrast to RCC

Question 21

Cystic nephroma

Answer 21

Rare benign tumor in boys 2-3 yo and adults
Difficult to distinguish from WT
Manage as per COG guidelines

Resect when feasible

Patho: lack of blastemal and embryonal elements vs Wilms

Question 22

Mixed epithelial and stromal tumors (MESTs)

Answer 22

Benign tumors in perimenopausal women (hx of estrogen replacement), peak incidence 5th decade

Complex cystic mass, Bosniak III-IV lesion, similar to RCC

Usually diagnosed after resection

Question 23

Leiomyoma

Answer 23

Rare tumor of smooth muscle differentiation

Anywhere in the GU: most common: bladder

Hypoenhancing on IV contrast administration

Nephron-sparing approach preferred

Question 24

Hemangiomas

Answer 24

Association with syndromes such as Klippel-Trenaunay, Struge-Weber, and systemic angiomatosis
No capsule
Irregular vascular spaces

Question 25

Lymphangiomas

Answer 25

Perirenal lymphatics do not communicate with the lymphatic system –> dilated cystic masses

Question 26

Juxtaglomerular tumor

Answer 26

A.k.a. reninoma or JGCT
Overproduction of renin –> Sx of hyperaldosteronism (polydipsia, polyuria, myalgias, double vision, headaches, and headaches

Examination: hypertension, hypokalemia, and proteinuria

Resection results in resolution in majority
10% persistent hypertension due to angiopathy

Question 27

Renomedullary interstitial cell tumor

Answer 27

Arises within the renal medullary tissue. The cells of origin, renomedullary inter- stitial cells, synthesize prostaglandins; it was therefore thought to be the result of hypertension

Question 28

Intrarenal schwannomas

Answer 28

Arising from nerve sheath tissue in the renal parenchyma.

Present with nonspecific symptoms, such as malaise, weight loss, fever, and abdominal pain

Question 29

Solitary fibrous tumor

Answer 29

rare benign tumor of Mesenchymal origin that tends to occur with hematuria, flank pain, and an enlarging mass.

Masses are large with heterogenous enhancement, calcifications, and necrosis on CT that are hard to distinguish from RCC