A 43-year-old man undergoes abdominal ultrasonography for dyspepsia. Medical problems include gastroesophageal reflux disease. He is not overweight and has no history of hypertension. His father was diagnosed with colon cancer at age 65.
Temperature is 36.7 C (98.1 F), blood pressure is 120/60 mm Hg, pulse is 68/min, and respirations are 18/min. Physical examination is unremarkable.
Ultrasound of the abdomen reveals gallbladder sludge. There is also a 2.4-cm right renal cyst that is round, has smooth walls, is anechoic, and demonstrates strong posterior wall enhancement. Laboratory studies show hemoglobin of 14.5 g/dL and serum creatinine of 0.8 mg/dL. Urinalysis is unremarkable.
Which of the following is the best next step in management of this patient's renal cyst?

Question

A 43-year-old man undergoes abdominal ultrasonography for dyspepsia.  Medical problems include gastroesophageal reflux disease.  He is not overweight and has no history of hypertension.  His father was diagnosed with colon cancer at age 65.
Temperature is 36.7 C (98.1 F), blood pressure is 120/60 mm Hg, pulse is 68/min, and respirations are 18/min.  Physical examination is unremarkable.
Ultrasound of the abdomen reveals gallbladder sludge.  There is also a 2.4-cm right renal cyst that is round, has smooth walls, is anechoic, and demonstrates strong posterior wall enhancement.  Laboratory studies show hemoglobin of 14.5 g/dL and serum creatinine of 0.8 mg/dL.  Urinalysis is unremarkable.
Which of the following is the best next step in management of this patient's renal cyst?

Quizplus · Accepted Answer

11ec193a_990a_ec50_853d_699e663e6495_MD0002_00 Renal cysts are classified as simple or complex based on imaging characteristics. Most (60%-70%) are simple cysts (Bosniak category I), occurring more commonly at age >50. These cysts are typically asymptomatic and do not cause renal damage or hypertension; they can be solitary/multiple or unilateral/bilateral. As seen in this patient, a simple cyst can be diagnosed using ultrasound alone when all of the following features are present: simple or complex A round mass with thin, smooth wallsClear (anechoic) fluidPosterior wall enhancement (a technical artifact seen on ultrasound studies that indicates ultrasound wave transmission beyond the cyst; it does not equate with contrast enhancement on CT scan/MRI) A round mass with thin, smooth walls A round mass with thin, smooth walls Clear (anechoic) fluid Clear (anechoic) fluid Posterior wall enhancement (a technical artifact seen on ultrasound studies that indicates ultrasound wave transmission beyond the cyst; it does not equate with contrast enhancement on CT scan/MRI) Posterior wall enhancement (a technical artifact seen on ultrasound studies that indicates ultrasound wave transmission beyond the cyst; it does not equate with contrast enhancement on CT scan/MRI) For a simple cyst, CT scan/MRI is not required for diagnosis but would reveal no contrast enhancement (ie, avascular lesion). Because simple cysts have a very low malignancy risk (<1%), patients can be reassured without the need for follow-up imaging unless complications (eg, infection, hemorrhage, pain) are suspected. Complex cysts (Bosniak categories II and IIF) have more septations, calcifications, or changes in wall size. CT scan/MRI with contrast reveals no measurable enhancement. Complex cysts with certain features (see Bosniak IIF in table) have a higher risk (~5%-10%) of malignancy and require follow-up imaging in 6-12 months (Choice E). Cystic masses (Bosniak categories III and IV) have a thick, irregular wall with multiple thick septa that are often calcified. Lesions usually enhance on CT scan/MRI, and category IV lesions have enhancement in soft tissue components adjacent to the wall or septum. Cystic masses are usually surgically resected given the higher risk (~90%) of malignancy. Complex cysts with measurable enhancement are treated as cystic masses. Some clinicians adopt a more conservative approach for Bosniak category III cysts (eg, needle biopsy, close monitoring with repeat imaging). (Choice A) CT scan of the abdomen is usually reserved for lesions with indeterminate ultrasound findings. CT scan with intravenous contrast can assess for contrast enhancement (increased density >10-15 Hounsfield units) in the cyst, which increases the risk for malignancy. (Choice B) Mismatch repair gene mutations are associated with Lynch syndrome (hereditary nonpolyposis colorectal carcinoma), an autosomal dominant condition conferring an increased risk of colorectal cancer, renal transitional cell carcinoma, cancer involving the ureter/renal pelvis, and uterine carcinoma. This patient's ultrasound findings are consistent with a simple cyst that does not require further testing. (Choice C) Percutaneous needle aspiration of the cyst is indicated for lesions that demonstrate an abscess or purulent fluid, are large (>10 cm) and painful, or are suspicious for malignancy (eg, papillary renal cell carcinoma). Educational objective: A simple renal cyst is the most common renal lesion and is usually seen in adults age >50. A simple cyst is round with thin, smooth walls; is anechoic; reveals posterior wall enhancement on ultrasound; and does not enhance with intravenous contrast on CT scan/MRI. Simple cysts are benign and do not require follow-up imaging unless symptomatic (eg, hemorrhage, infection, pain). __________ References: A clinical view of simple and complex renal cysts. (http://www.ncbi.nlm.nih.gov/pubmed/18776117)

A 43-Year-Old Man Undergoes Abdominal Ultrasonography for Dyspepsia