A 63-year-old man comes to the emergency department due to fever and loss of appetite. He also has chest pain with deep breaths. The patient has never had regular medical care and his medical history is unknown. He has smoked half a pack of cigarettes daily for 30 years. Laboratory evaluation shows a hematocrit of 56%. Chest imaging shows multiple round lesions in both lungs. Biopsy of one of the lesions reveals the microscopic findings shown below. This patient's metastatic disease most likely originated from which of the following organs?

Question

A 63-year-old man comes to the emergency department due to fever and loss of appetite.  He also has chest pain with deep breaths.  The patient has never had regular medical care and his medical history is unknown.  He has smoked half a pack of cigarettes daily for 30 years.  Laboratory evaluation shows a hematocrit of 56%.  Chest imaging shows multiple round lesions in both lungs.  Biopsy of one of the lesions reveals the microscopic findings shown below.  This patient's metastatic disease most likely originated from which of the following organs?

Quizplus · Accepted Answer

11ec160b_3a4b_ccdd_9249_832f55beb144_MD0001_00 This patient has fevers, anorexia, and polycythemia. His evaluation shows multiple round lung lesions with microscopy revealing rounded polygonal cells with abundant clear cytoplasm. This presentation is consistent with metastatic clear cell carcinoma, the most common subtype of renal cell carcinoma (RCC). The cytoplasm appears clear due to the high glycogen and lipid content of the tumor. For the same reason, this neoplasm is often golden-yellow on macroscopic examination. Patients with RCC are often asymptomatic; the classic triad of hematuria, flank pain, and palpable abdominal mass occur together in less than 10% of cases, often late in the course of the disease. Nonspecific symptoms such as fever and weight loss are more common. Paraneoplastic syndromes, including polycythemia (constitutive secretion of erythropoietin) and hypercalcemia (synthesis of parathyroid hormone-related protein), can also occur. Renal cell carcinoma is often detected incidentally since localizing symptoms only develop in advanced disease; metastases are often discovered earlier than the primary neoplasm. RCC most commonly metastasizes to the lungs, where it often presents as large, rounded, well-circumscribed "cannonball" metastases. Osteolytic bone lesions and liver metastases also occur frequently. (Choice A) Osteosarcoma frequently metastasizes to the lungs, but most patients have localized pain at the primary site (eg, distal femur), and polycythemia is unexpected. Histologically, pleomorphic malignant tumor cells with osteoid matrix production would be seen. (Choice B) Primary brain neoplasms usually metastasize within the CNS; although they can rarely metastasize outside the nervous system, they would not be associated with polycythemia. (Choices C and E) Colon and stomach cancers commonly metastasize to the lungs. Microscopy of diffuse-type gastric adenocarcinoma demonstrates signet ring cells with clear cytoplasmic mucin and eccentric nuclei (resembling a signet ring). Colonic adenocarcinoma forms glands and tubules. However, patients typically develop anemia due to occult bleeding, not polycythemia. (Choice F) Testicular cancer also commonly metastasizes to the lung, but patients typically have a testicular mass. β-hCG or alpha-fetoprotein are often elevated; however, hematocrit elevations are unexpected. Histology varies by malignancy. Educational objective: Clear cell carcinoma is the most common subtype of renal cell carcinoma and is composed of large, rounded, or polygonal cells with clear cytoplasm. These tumors are often detected incidentally at an advanced stage; the lung is the most common site for metastasis, followed by osteolytic bone and liver.

A 63-Year-Old Man Comes to the Emergency Department Due to Fever