A 50-year-old man comes to the office for evaluation of abdominal fullness and mild right flank pain. He also reports a weight loss of 4.5 kg (10 lb) over the past 2 months. The patient has no other medical issues and works in a local industrial chemical manufacturing facility. Examination shows a soft abdomen. Ultrasound reveals a mass in the right kidney. A subsequent abdominal CT scan confirms the presence of a large right renal mass with evidence of necrosis. The patient undergoes a right total nephrectomy. The specimen is shown below. This patient's lesion most likely originated from which of the following portions of the kidney?

Question

A 50-year-old man comes to the office for evaluation of abdominal fullness and mild right flank pain.  He also reports a weight loss of 4.5 kg (10 lb) over the past 2 months.  The patient has no other medical issues and works in a local industrial chemical manufacturing facility.  Examination shows a soft abdomen.  Ultrasound reveals a mass in the right kidney.  A subsequent abdominal CT scan confirms the presence of a large right renal mass with evidence of necrosis.  The patient undergoes a right total nephrectomy.  The specimen is shown below.  This patient's lesion most likely originated from which of the following portions of the kidney?

Quizplus · Accepted Answer

11ec160b_3a4c_691f_9249_d512b7af0815_MD0001_00 This patient with a history of chemical exposure and a necrotic kidney mass likely has renal cell carcinoma (RCC), the most common renal malignancy. RCC originates in the renal cortex and occurs most commonly in patients age 60-70. Risk factors include smoking, obesity, hypertension and toxin exposure (eg, heavy metal, petroleum by-products, asbestos). RCC is classified into subtypes based on cellular origin; clear cell carcinoma (CCC) is the most common type and accounts for up to 85% of RCCs. CCC originates from the epithelium of the proximal renal tubules. Gross pathology typically demonstrates a sphere-like mass composed of golden-yellow tissue (due to high lipid content) with areas of focal necrosis and hemorrhage. It often invades the renal vein and may extend into the inferior vena cava. On microscopy, CCC appears as cuboidal or polygonal cells with abundant clear cytoplasm. (Choice A) Angiomyolipomas are rare tumors that arise from perivascular epithelioid cells. Gross pathology demonstrates a well-circumscribed tumor composed of variable amounts of 3 different tissue types: yellow adipose tissue, red vascular components, and grayish smooth muscle. Angiomyolipomas are benign neoplasms often associated with tuberous sclerosis. (Choice B) Renal oncocytomas are rare tumors that originate from collecting duct cells. Gross pathology often demonstrates a homogenous brown tumor with a central stellate scar that is often visible on imaging; focal areas of necrosis are rare. (Choice C) Glomerular diseases (eg, membranous nephropathy, minimal change disease) can be seen as a paraneoplastic syndrome associated with certain malignancies (eg, lung, gastrointestinal tumors), but the glomeruli are not the site of origin of RCC. (Choice E) Urothelial carcinoma arises from the epithelium of the renal pelvis, ureters, or bladder and may be multifocal in nature. It often forms papillary tumors composed of urothelium supported by a thin fibrovascular stalk. Educational objective: Clear cell carcinoma is the most common type of renal cell carcinoma and originates from the epithelial cells of the proximal renal tubules. Gross pathology typically demonstrates a sphere-like mass composed of golden-yellow cells (due to high lipid content) with areas of necrosis and hemorrhage.

A 50-Year-Old Man Comes to the Office for Evaluation of Abdominal