Correspondence Division of Pulmonary and Critical Care Medicine, University of California, San Diego Medical Center, 9300 Campus Point Drive, 7381, La Jolla, CA 92037, USA

Email kmkerr@ucsd.edu

The case

A 40-year-old woman experienced a gradual onset of dyspnea during the fifth month of pregnancy with her second child. The pregnancy was otherwise unremarkable. Two weeks after spontaneous vaginal delivery she awoke with a sudden onset of right-sided chest pain and a marked increase in dyspnea. She was hospitalized and diagnosed as having acute pulmonary embolism by CT angiography, and treated with heparin followed by warfarin. She experienced a mild improvement in symptoms, but a repeat CT angiogram after 2 months of anticoagulation showed no improvement (Figure 1).

Figure 1 Transverse CT angiogram demonstrating a large mass almost totally occluding the right main pulmonary artery with extension into the interlobar artery (thick arrows)

The mass is also seen lining the left descending pulmonary artery (thin arrow).

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The patient presented to her referring pulmonologist 6 months after initial hospitalization; she reported persistent dyspnea on exertion and an episode of hemoptysis. Lower-extremity duplex ultrasonography was negative. Ventilation–perfusion scanning demonstrated large mismatched perfusion defects and echocardiography showed right-ventricular enlargement with estimated pulmonary artery systolic pressure 75 mmHg. At this point CHRONIC THROMBOEMBOLIC PULMONARY HYPERTENSION (CTEPH) was diagnosed. Sildenafil therapy was started and the patient was referred to our clinic for pulmonary thromboendarterectomy.

The patient complained of dyspnea and fatigue upon mild exertion. She reported no lower-extremity edema, chest pain, palpitations, lightheadedness, syncope, weight loss, fever, rashes or arthritis. There was no history of estrogen, appetite suppressant or illicit drug use, deep-venous thrombosis, or familial pulmonary hypertension or thromboembolic disease. She had a 15 pack-year history of tobacco use but had quit 3 years before presentation.

She was in no apparent distress at rest and there was no jugular venous distension. PULMONARY FLOW MURMURS were audible over the right and left posterior lung fields. A right-ventricular heave was present; S1 was normal but widening of the second heart sound was heard, with an accentuated pulmonary component and a grade 3/6 holosystolic murmur across the precordium. The abdomen and extremities were normal and there was no clubbing.

Serum chemistries, complete blood count and tests for a hypercoagulable state were normal. Chest radiography revealed right-ventricular enlargement, prominent central pulmonary arteries, patchy alveolar opacities in the right lower lobe and several linear opacities in the upper lobes. A perfusion scan demonstrated an absence of perfusion to the right lower lobe and large perfusion defects in the right middle and left lower lobes (Figure 2); ventilation scan was normal. Echocardiography revealed severe enlargement of the right atrium and ventricle, mild tricuspid regurgitation, normal left-ventricular size and function and a 'late positive' BUBBLE CONTRAST STUDY. Right-heart catheterization revealed the hemodynamics listed in Table 1. Pulmonary angiography (Figure 3) showed a bulky, irregular filling defect in the right main pulmonary artery extending into the right upper lobe and interlobar artery, with a small amount of flow distal to the near-occlusive lesion. On the left, there were marked luminal irregularities in the wall of the descending pulmonary artery, with narrowing of the upper lobe and occlusion of several of the basilar segments of the lower lobe. The large, proximal, irregular intraluminal masses seen on CT scanning and pulmonary angiography did not change with anticoagulation, and were considered more compatible with sarcoma than chronic thromboembolic disease.

Figure 2 Perfusion scan (posterior view)

There was an absence of perfusion to the right lower lobe, large segmental perfusion abnormalities in the right middle and left lower lobes and subsegmental perfusion defects in the upper lobes.

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Figure 3 Pulmonary angiogram

(A) Near-total obstruction of the right main pulmonary artery by an irregular mass is seen (black arrow). The right upper lobe artery is narrowed and irregular in contour with an intraluminal filling defect. A tiny amount of contrast is seen in the right middle lobe. (B) The left descending pulmonary artery (black arrow) is lobular in appearance with minimum flow to the left lower lobe (white arrow). Vessel narrowing is also noted in the proximal and midsegmental regions of the left upper lobe.

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Table 1 Hemodynamics measured upon right-heart catheterization

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The patient underwent pulmonary endarterectomy. During surgery a large, lobular mass originating in the pulmonary trunk and extending throughout the vasculature of both lungs was noted (Figure 4). Because of tumor invasion through the vessel wall into adjacent lung parenchyma as well as distal extension of tumor into segmental and subsegmental arteries, complete resection was impossible; however, tumor debulking led to reperfusion of the right middle and lower lobes and reduced pulmonary artery pressures (Table 1). Pathology revealed an undifferentiated intimal sarcoma. The patient was subsequently referred to oncology for adjuvant chemotherapy or radiation therapy.

Figure 4 Resected sections of the pulmonary artery sarcoma from the pulmonary trunk and the right and left pulmonary arteries by pulmonary endarterectomy

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Discussion of diagnosis

Epidemiology, pathology and clinical presentation

Primary pulmonary artery sarcomas are extremely rare. Since Mandelstamm's initial description in 1923, approximately 200 cases have been reported in the literature. Their true incidence is unknown, but is probably underestimated through misdiagnosis as pulmonary embolism, and because accurate diagnosis requires pathologic examination. The etiology of these tumors is obscure and no risk factors have been identified. Although some studies have previously shown a slight female predominance,^{1, 2} a roughly equal sex distribution is now reported, with an average presentation age of 49.3 years.³

These tumors present as intimal or mural sarcomas, although most arise in the intima. Grossly, intimal sarcomas resemble mucoid, gelatinous clots filling the artery lumen. They extend distally, sometimes invading the adventitia or pulmonary parenchyma.⁴ Most demonstrate bilateral pulmonary artery involvement and are commonly located in the pulmonary trunk (85%) and right and left pulmonary arteries (71% and 65%, respectively). Some involve the pulmonary valve (32%) and the right-ventricular outflow tract (10%).³ Intimal sarcomas are usually poorly or not differentiated; patchy areas of spindle-cell proliferation alternate with areas of hypocellular collagenous stroma. Recanalized thrombi may be incorporated.⁴ In a review of 23 cases, malignant fibrous histiocytoma was the most common histologic subtype, occurring in a third of patients.⁵

Patients usually present with pulmonary artery obstruction, pulmonary hypertension and right-ventricular failure, leading to the symptoms listed in Table 2.³ Misdiagnosis as pulmonary thromboembolism is frequent, and was a logical initial diagnosis in the patient described. A few patients present with systemic symptoms such as fever or weight loss, which differentiate the presentation from chronic thromboembolic disease.

Table 2 Clinical features of pulmonary artery sarcomas^a

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Physical examination findings of CTEPH and pulmonary artery sarcomas include jugular venous distension, bruit over the pulmonary artery, cardiac murmur, hepatomegaly, edema and cyanosis. Clubbing can be seen with sarcomas, but not CTEPH.^{1, 3, 6} The physical examination of the patient we report indicated pulmonary hypertension thought to be due to partial obstruction of the larger pulmonary arteries because of pulmonary flow murmurs. No physical sign, however, differentiated the underlying diagnosis from other causes of pulmonary artery obstruction.

Treatment and management

Surgical resection offers palliation of symptoms and improved short-term survival; in localized lesions resection can be curative. The roles of chemotherapy and radiation remain undefined. Surgical options include endarterectomy, tumor and pulmonary artery resection and reconstruction, lobectomy and pneumonectomy, with approach dictated by tumor location, distal extension and metastatic spread.^{1, 3, 5, 10}

Kruger et al.¹ reviewed 93 cases reported before 1990. Median survival was 1.5 months from diagnosis, but was 10 months in 27 patients who underwent resection. Prognosis after successful surgery seems dependent on tumor recurrence rather than metastatic progression. In a review of 138 cases, 1-year survival was 31% among 35 resected patients, compared with 5% among 74 nonresected patients; survival at 5 years was 6% and zero, respectively.³ Survival at 1 and 2 years was nonsignificantly improved with adjuvant radiotherapy, chemotherapy or both. Devendra et al.¹⁰ reported on 16 pulmonary artery sarcoma patients. Average survival was 17 months after surgery, with one patient alive at 54 months.¹⁰

The leading preoperative diagnosis in the case we report was pulmonary artery sarcoma. Although CTEPH remained a possibility, surgery is indicated for either disease process and we elected to forgo further testing such as MRI or biopsy. Endarterectomy would be portentially curative for CTEPH or would alleviate symptoms and prolong survival if sarcoma were the underlying diagnosis. Despite complete resection being impossible, surgery did result in improved pulmonary hypertension and reperfusion of some lung segments. Once recovered from surgery the patient will undergo adjunctive therapy in an attempt to prolong survival, but long-term prognosis is poor.

Conclusion

This case describes pulmonary artery sarcoma masquerading as thromboembolic disease, illustrating the importance of considering these rare tumors in the differential diagnosis of pulmonary artery obstruction. Further investigation to differentiate the diagnosis from pulmonary embolism should be prompted by systemic symptoms and pulmonary perfusion abnormalities that fail to improve with anticoagulation. Although short-term survival can be prolonged, most patients eventually die from progressive obstruction of the pulmonary artery resulting in pulmonary hypertension and right-ventricular failure. The role of adjuvant treatments has yet to be determined.

References

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8. Schermoly M et al. (1987) Pulmonary artery sarcoma—unusual pulmonary angiographic finding—a case report. Angiology 38: 617–621 | PubMed | ChemPort |
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10. Devendra G et al. (2002) Pulmonary artery sarcomas: the UCSD experience [abstract]. Am J Resp Crit Care Med 165: A24

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Subject areas under which this article appears: Concomitant disease