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* From the Departments of Pulmonary Medicine (Drs. A. Singh, LaFalce, Shade, and N. Singh) and Cardiothoracic Surgery (Dr. Marrone), Allegheny General Hospital, Pittsburgh, PA.
Correspondence to: Anil C. Singh, MD, Department of Pulmonary Medicine, Allegheny General Hospital, 320 E North Ave, Pittsburgh, PA 15212; e-mail: anils_ka{at}hotmail.com
A 71-year-old man presented with complaints of increasing dyspnea on exertion to his family physician. Pulmonary embolism was suspected because 6 months previously the patient underwent bilateral knee arthroplasty. CT angiography of the thorax was performed revealing bilateral filling defects in the main pulmonary arteries (Fig 1 ). The patient was anticoagulated with heparin, transitioned to warfarin, and was subsequently discharged.
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The patient’s medical history included rheumatoid arthritis, gastroesophageal reflux disease, and depression. He had a smoking history of 1 pack per day for 40 years and worked as an auto parts salesman.
Physical Examination and Laboratory Data
On arrival to our hospital, the patient appeared nontoxic and was able to speak in full sentences. He was afebrile with normal respirations. BP was 144/63 mm Hg, and pulse rate was regular at 72 beats/min. Oxygen saturation was 98% on 4 L of oxygen via nasal cannula. His lungs were clear to auscultation, and cardiac examination revealed a regular rate without the presence of gallops, rubs, or murmurs. Cardiac enzymes were negative; and ECG, renal function, electrolytes, and hematologic profile were normal other than a hemoglobin level of 8.7 g/dL. His stool was heme positive, but the risk of bleeding was outweighed by the clinical and radiologic findings; therefore, anticoagulation was continued.
Hospital Course
The patient was admitted to our ICU. A repeat CT angiogram demonstrated a large intraluminal density involving the main, left, and right pulmonary arteries (Fig 2 ). Duplex ultrasound of the lower extremities was negative for thrombus. Echocardiography did not indicate the presence of right ventricular strain or dysfunction, and pulmonary artery pressures were normal.
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What is your diagnosis?
Diagnostic approach: Open biopsy
Diagnosis: Intimal pulmonary artery sarcoma
Pulmonary artery sarcomas are very rare tumors, with a reported incidence of 0.001 to 0.003% and a total of 148 cases reported as of 2001. Mortality is virtually 100%. However, there is reported survival when the diagnosis is established early. The diagnosis is often difficult and delayed because the clinical presentation and radiographic findings can be indistinguishable from thromboembolic disease and tumor emboli. Consequently, pulmonary artery sarcomas are underrecognized and underreported. However, there are several features that may help differentiate between thromboembolic disease and primary tumors of the pulmonary artery. Patients with pulmonary artery tumors will generally have a gradual, progressive, subacute to chronic course characterized by weight loss, fatigue, weakness, and fever. These features are generally absent from those in patients with thromboembolic disease. Normal findings on venography or Doppler ultrasound of the lower extremities and deep pelvic veins can help exclude venous thrombosis as an underlying cause. Serial ventilation/perfusion scanning demonstrate static or progressive defects, as opposed to changing perfusion defects seen more commonly in treated patients with thromboembolic disease. Pulmonary angiography may reveal a smooth gradual tapering of the pulmonary artery and pruning of the distal vessels. This is more suggestive of tumor and less likely evident in thromboembolism. A characteristic oscillating motion that simulates a tumor on a pedicle is heralded as pathognomonic for tumor and is unlikely to be present in thromboembolism. Once a diagnosis is established, mean survival is only 1.5 months without surgical intervention; therefore, early diagnosis is essential in treatment.
Pulmonary artery sarcomas were first described by Mandelstamm in 1923. Since then, case reports and a few case series have appeared in the literature. In general, the average age on presentation is 52 years, with a range from 13 to 81 years. Some studies have suggested a slight female predominance, while others suggest an equal sex distribution. These tumors primarily metastasize to the mediastinum and lung (50%), with distant extrathoracic metastasis occurring in almost any organ (16%).
Grossly, intimal sarcomas resemble mucoid or gelatinous clots that appear as polypoid, intraluminal, or nodular sessile masses. These spread to fill the lumen of the pulmonary artery, giving the appearance of organized thrombi. The underlying pathophysiology of this tumor is not fully understood, but the most widely accepted hypothesis is that they arise from primitive mesenchymal cells in the intima of the pulmonary arteries.
Histologic patterns observable include undifferentiated sarcomas accounting for the majority of reported cases (37%), followed by leiomyosarcomas (17 to 20%). Fibrosarcoma, rhabdomyosarcoma, malignant mesenchymoma, angiosarcoma, myxosarcoma, chrondrosarcoma, osteosarcoma, malignant fibrous histiocytoma, and liposarcoma have all been described, but these histologic descriptions have not been shown useful clinically or prognostically.
The presence of tumor in the pulmonary artery usually does not result in symptoms until the insidious growth or distal embolization results in right ventricular dysfunction. Peripheral emboli to the distal pulmonary circulation may account for exacerbations of chest pain, dyspnea, and even pulmonary infarction, which may lead to hemoptysis. This is the likely mechanism of exacerbation in our particular patient. Nonspecific signs and symptoms such as fatigue, weakness, weight loss, digital clubbing, anemia, and lack of response to anticoagulation are features of malignant disease. A high erythrocyte sedimentation rate 50 mm/h has been used to distinguish between pulmonary thromboembolism and tumor. Unusual presentations include bleeding diathesis, polycythemia, thrombocytopenia, heparin-induced thrombocytopenia, and activated protein C resistance. The underlying pathogenesis of these presentations are not completely understood.
Several diagnostic techniques have been described to establish a diagnosis. Bronchoscopy is only useful if the neoplasm has invaded the wall of the bronchus. Ventilation/perfusion scan may show perfusion defects but are generally indistinguishable for thromboembolic disease. Microscopic tumor emboli may result in an abnormal radionuclide perfusion that may be indistinguishable from thromboembolic disease, but rarely results in pulmonary angiographic findings except when they are associated with hepatoma and renal cell cancers. CT angiography has recently been shown to have some distinguishing features that may aid in diagnosis. In contrast to the abrupt vascular narrowing in embolic disease, tumors of the pulmonary artery form a contiguously soft tissue-filled pulmonary artery, sometimes with vascular distension and extravascular spread. In addition, Yi et al identified 7 patients with pulmonary artery sarcoma and 40 patients with pulmonary embolism using CT. Pulmonary artery sarcomas tended to have lower-attenuation filling defects, and occupied the entire luminal diameter of the main or proximal pulmonary artery. Lesions resulting in luminal obliteration of proximal pulmonary arteries were absent in all 40 patients with pulmonary embolism. Angiography may demonstrate filling defects due to sarcoma that may be described as lobulated, polypoid, and may show an oscillating motion. MRI with gadolinium enhances pulmonary artery sarcoma, which helps differentiate these intraluminal abnormalities from embolic disease. Therefore, it has been useful in the preoperative diagnosis and may assess results of surgical treatment.
Although imaging modalities have improved significantly, no single modality has 100% accuracy. Obtaining tissue remains necessary to definitively diagnose sarcoma. Endovascular biopsy has recently been described at our institution as a useful modality in high-risk operative patients, but open biopsy is still the method of choice.
Pulmonary artery sarcomas are highly malignant, with a median survival time of 1.5 months without surgical intervention. The mean survival regardless of therapy ranges from 14 to 18 months. Five-year survival has been reported in two cases of mural sarcoma and one case of low-grade intimal sarcoma.
Surgical resection offers the most effective treatment modality for palliation and improves survival. Surgical therapy includes local excision, endarterectomy, pneumonectomy, and pulmonary artery reconstruction. One patient who underwent tumor resection with pulmonary artery reconstruction for a low-grade sarcoma was alive after 5 years. The role of adjuvant treatment is still controversial, but reports suggest that postsurgery chemotherapy or radiation therapy improved 1-year and 2-year survival. One case report suggested successful treatment with four cycles of ifosfamide and epirubicin in an unresectable patient.
Our patient presented with shortness of breath that was initially diagnosed as a pulmonary embolism and treated with anticoagulation (Fig 1). Despite adequate anticoagulation for 6 months, his symptoms persisted. A repeat CT angiogram revealed progression of the filling defects in the main, left, and right pulmonary arteries (Fig 2). Doppler ultrasound revealed absence of clot in the deep veins of the lower extremities. Echocardiography and right-heart catheterization demonstrated a normal-appearing right ventricle with only mild pulmonary artery hypertension. At this point, the differential diagnosis broadened to include a tumor of the pulmonary artery, as thromboembolic disease would have been unlikely 9 months after the patient’s total knee arthroplasty. Generally, the rates of symptomatic venous thromboembolism are reported to occur in 1.5 to 10% of patients after hip or knee arthroplasty within 3 months. MRI with gadolinium helped confirm the diagnosis as gadolinium enhances tumor and not thrombus (Fig 3). Endovascular biopsy was attempted but was unsuccessful. The patient subsequently underwent an open biopsy. The tissue revealed high-grade malignancy composed of spindle cells and pleomorphic giant tumor cells consistent with intimal sarcoma. The tumor was unresectable, and the patient is currently being treated with combination chemotherapy with ifosfamide and adriamycin. He remains mildly short of breath but is still able to carry out his normal activities of daily living.
Clinical Pearls
Footnotes
The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
Received for publication November 21, 2005. Accepted for publication December 16, 2005.
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