10

Kidney

Renal Cyst

Overview

Usually benign and found in population over the age of 50 years

Signs and Symptoms

Usually asymptomatic and incidentally found on imaging

Diagnosis

CT, ultrasound, or MRI

Treatment

Majority do not require treatment

Percutaneous drainage for symptomatic benign cysts

Partial or total nephrectomy for complex cystic lesions suspicious of malignancy

RADIOLOGY

US findings

• Anechoic, well-defined masses, with thin walls and posterior acoustic enhancement

CT findings (Fig. 10.1)

• Well-defined rounded mass with low attenuation values of 0 to 20 HU

• Well defined walls with or without septae (refer to Bosniak classification)

• No internal enhancement on post contrast images

MRI findings

• Well defined lesion usually with low signal intensity on T1-weighted images if it contains simple fluid, or higher signal intensity if it contains blood

• Uniformly hyperintense on T2-weighted images

• No internal enhancement after contrast medium administration

FIGURE 10.1 A–C

A. Vertebra

B. Descending aorta

C. IVC

D. Small bowel loops

E. Liver

F. Stomach

G. Spleen

H. Psoas muscle

FIGURE 10.1 A

FIGURE 10.1 B

FIGURE 10.1 C

Renal Cell Carcinoma

Overview

Most common kidney cancer in the adult population

Most are found incidentally on radiology imaging

Most common in men ages 50 to 70 years of age

Risk factors include smoking and obesity

Clinical Presentation

Flank pain, hematuria, palpable flank mass (10% of patients have this triad)

Weight loss

Common sites of metastasis are lung, bone, and liver

Diagnosis

Obtain a noncontrast study and a contrast study to look for increased enhancement of the mass after injection of contrast

If patient cannot receive contrast, consider an MRI with gadolinium, if GFR (glomerular filtration rate) > 30

CXR or Chest CT to rule out metastasis

Treatment

After appropriate staging is made, then perform radical or partial nephrectomy depending on the size or location of the tumor

Possibly requires immunotherapy such as interleukin-2 or interferon alpha

RADIOLOGY

Plain film findings

• Often normal unless mass is large or contains calcification

• Mass effects on nearby organs may be seen if tumor is very large

CT findings (Fig. 10.2)

• Enhancement pattern may be heterogeneous due to the presence of hemorrhage and/or necrosis

• Detection of small hypervascular RCC masses is optimal in the corticomedullary or nephrographic phase

• RCC usually shows a lobular margin with adjacent normal tissue but can sometimes infiltrate calyces or the renal pelvis

• Tumor spread through the renal veins and into the IVC may warrant cardiopulmonary bypass if tumor resection is elected

MRI findings

• Renal cell carcinomas demonstrate contrast enhancement on T1-weight images, and variable signal characteristics on T2-weighted images

FIGURE 10.2 A,B

A. Kidney

B. Vertebra

C. Descending aorta

D. IVC

E. Transverse colon

F. Small bowel loops

G. Liver

H. Stomach

I. Spleen

FIGURE 10.2 A

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