Diagnostic Puzzlers: What caused this patient's chest wall mass?

A 66-year-old man presented with weight loss for 2 months, loss of appetite for several weeks, and abnormal chest radiographic findings. He denied chest pain, cough, fever, chills, shortness of breath, and chest trauma. He was an active smoker, with a 50-pack-year history of smok- ing, and a cocaine and alcohol abuser. His history included treatment of hypertension for 10 years and treatment of pulmonary tuberculosis 14 years previously.

Physical examination revealed a chronically ill-appearing man with normal vital signs and no lymphadenopathy. Findings from the chest examination were remarkable for a hard mass (5 3 5 3 2 cm) on the left lateral chest wall. The mass had a smooth surface and round edges, and the overlying skin was freely mobile over the mass. The results of a tes- ticular examination were normal. Findings from the rest of the examination were normal.

Laboratory studies revealed normocytic-normochromic anemia (hemoglobin, 12 g/dL; hematocrit, 36%) and thrombocytosis. The serum calcium level was elevated to 13 mg/dL. All liver enzyme levels were elevated. Results of a serologic test for hepatitis C virus antibody were positive. The serum a-fetoprotein level was elevated above 2000 µg/L. Serum protein electrophoresis revealed a diffuse hypergammaglobulinemia with hypoalbuminemia.

The patient's chest radiograph and CT scan are shown below (Figures 1 and 2). Bronchoscopy revealed no endobronchial lesions and was nondiagnostic. The patient became hemodynamically unstable on the medical ward, and he was sent to the ICU. Emergent CT of the abdomen and peritoneal tap prompted immediate transfer to the operating room, but the patient died en route. An autopsy was performed.

What was the likely diagnosis?

What caused this patient's chest wall mass? The patient's chest radiograph revealed an elevated right hemidiaphragm and 2 left-sided extrapleural masses (Figure 1). The chest CT scan confirmed these findings and also showed a right-sided extrapleural mass eroding one of the vertebra (Figure 2). The results of the autopsy demonstrated metastatic hepatocellular carcinoma involving the chest wall, with multiple extrapleural masses. There was primary hepatocellular tumor erosion into a hepatic artery with bleeding into the peritoneum.

DISCUSSION

In adults, an extrapleural mass (or masses) represents any tissue that can transform into a benign or malignant tumor and becomes part of the chest wall; this includes fat, connective tissue, nerves, bone, cartilage, fibrous tissue, blood, and lymphatic vessels. The most common causes of extrapleural masses are rib fractures with hematoma or metastatic cancer to the ribs.¹ Metastasis to the rib is usually associated with lung or breast cancer²; however, any tumor capable of bony metastasis can metastasize to the rib.

Common benign tumors of the chest wall include lipoma, neural-derived tumors, osteochondroma, chondroma, and fibromas. Multiple myeloma is the most common primary tumor of the rib cage and accounts for up to one third of all chest wall tumors.^2,3 Occasionally, tumors originating from the pleura, such as malignant mesothelioma and the solitary fibrous tumor, can cause an extrapleural mass.^4,5

Tumors that expand into the chest cavity external to the parietal pleura tend to form an obtuse angle with the chest wall and develop a convex border. This is the classic radiologic presentation of the extrapleural mass, as seen in this case (Figures 1 and 2).

The tip-off that the primary diagnosis was metastatic hepatocellular carcinoma was the very elevated a-fetoprotein level (greater than 2000 µg/L), which occurs in up to 80% of patients with liver cancer. Levels above 2000 µg/L are extremely rare in other tumors. Mildly elevated a-fetoprotein levels (usually less than 500 µg/L) can occur in patients with nonseminomatous testicular tumors or large gastric or colonic tumors. Mildly elevated levels can also occur with other tumors of the GI tract as well as with hepatitis, cirrhosis, and pregnancy.⁶ The possibility of other GI tumors was considered unlikely because the patient's a-fetoprotein level was extremely high.

The patient's other risk factors for liver cancer included exposure to hepatitis C and alcohol abuse. Cirrhosis is also a risk factor, although the patient had no formal diagnosis of this disease.

Metastatic disease from hepatocellular carcinoma is usually to the lung and bone and less often involves the brain and adrenal gland. Hepatocellular carcinoma presenting as an extrapleural mass is rare. Fewer than 2% of cancers in the United States are primary hepatocellular tumors.⁷ In one series of 395 pathologically verified cases, 6 metastasized to the chest wall, and 1 was an extrapleural mass.⁸

In a second series of 300 patients with biopsy-proven hepatocellular cancer, 13 had rib metastasis and 2 had extrapleural masses.⁷ This indicates that fewer than 1% of primary hepatic tumors present with a metastatic extrapleural mass. Therefore, because of the patient's hypercalcemia, a diagnosis of multiple myeloma or other primary cancers with metastasis to bone might have been considered. It should be noted, however, that the bony lesions of metastatic hepatocellular carcinoma are osteolytic, which is consistent with this patient's elevated calcium level.

This case demonstrates the occurrence of an extrapleural mass representing metastatic primary hepatocellular carcinoma. The tip-off to the diagnosis was the concurrence of an extrapleural mass with an a-fetoprotein level above 2000 µg/L. To the best of our knowledge, this combination has not been described with any other type of cancer.

Case and figures courtesy of Samuel Dartey-Hayford, MD, Gene R. Pesola, MD, Rashid Mahboob, MD, and John Salazar-Schicchi, MD, division of pulmonary and critical care medicine, Harlem Hospital/Columbia University, New York.

References:

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