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Pulmonary artery intimal sarcoma: poor 18F-fluorodeoxyglucose uptake in positron emission computed tomography
© Lee et al; licensee BioMed Central Ltd. 2013
Received: 23 May 2012
Accepted: 4 March 2013
Published: 7 March 2013
Intimal sarcoma of the pulmonary artery is a rare malignant tumor that may be misdiagnosed as chronic pulmonary thromboembolism, even if various imaging techniques are used. We report a case of a 58-year-old man with pulmonary artery intimal sarcoma.18F-fleuorodeoxyglucose (FDG) uptake was poor in the mass of the pulmonary artery, and no other hypermetabolic lesions were noted elsewhere. Our presumptive diagnosis was a massive mural thrombus and a concomitant chronic thromboembolism. Intravenous heparin and recombinant human tissue-type plasminogen activator was subsequently administered. However, the patient needed an emergency operation for sudden aggravation of the vital signs, and the tissue diagnosis was intimal sarcoma with poor clinical outcomes.
Intimal sarcoma is a rare mesenchymal tumor, and it can arise from the great arteries. The incidence of pulmonary artery intimal sarcoma is almost twice that of the aorta . It usually arises from the intimal layer of the right, left, and main pulmonary arteries. The usual features of these tumors are endoluminal growth and later vessel obstruction or seeding of distal emboli. In addition, in rare cases, it may extend in a retrograde fashion to the pulmonary valve and the right ventricle [1, 2].
This tumor is highly malignant and the prognosis is very poor. Survival is usually 12 to 18 months after the onset of the symptoms . This disease mainly occurs in adults with female sex predominance, with the mean age at diagnosis being 48 years . The diagnosis is often delayed and difficult, due to gradually developing symptoms of the pulmonary artery obstruction and right heart failure with a long asymptomatic course.
A 58-year-old man was admitted with a month’s history of exertional dyspnea, which had been worsening for twenty days. The patient was being medicated for diabetes mellitus and hypertension. He was relatively stable, at New York Heart Association functional class II-III. On physical examination, the patient exhibited tachypnea, with 20 breaths per minute and his oxygen saturation was 92%, his pulse was regular at 95 beats per minute, and his blood pressure was 130/80 mmHg. Auscultation revealed a prominent second heart sound and grade 3/6 systolic murmur over the pulmonary area. A blood count revealed platelets at 57,000/mm3, but the rest of the work-up revealed no hematologic evidence of intrinsic hypercoagulability. The N-terminal pro-B-type natriuretic peptide level was 395 pg/ml (normal range: 0–125) and D-dimer was 0.816 μg/ml (normal range: 0–0.5). The chest radiograph revealed atherosclerotic cardiovascular change and mild cardiomegaly. Electrocardiography showed a sinus rhythm.
The intraoperative frozen biopsy was suggestive of sarcoma. We tried weaning the patient from cardiopulmonary bypass, but had to use extracorporeal membrane oxygenation (ECMO) due to the unstable vital status.
Given the poor prognosis and inability to wean the patient from the ECMO, we decided to withdraw the life support system after 5 days.
The clinical features of pulmonary intimal sarcoma are similar, and it is frequently misdiagnosed as chronic pulmonary thromboembolism. It may include right heart failure due to pulmonary hypertension, along with such as a cough, dyspnea, chest pain, hemoptysis, and syncope. However, if concomitant symptoms include fever, cachexia, and anemia but no risk factors for venous thrombosis, malignancy should be considered. In our case, our initial diagnosis was pulmonary thromboembolism due to laboratory tests and radiologic features. There was no hematologic evidence of intrinsic hypercoagulability, but D-dimer was 0.816 ug/ml (normal range: 0–0.5).
Advances in imaging technology, such as echocardiography, contrast-enhanced computed tomography, and magnetic resonance imaging, have supported better diagnoses of masses in the pulmonary artery, but without always differentiating successfully between a thrombus and a malignancy. The FDG-PET is a more reliable method for the confirmation of the neoplastic features and the distant metastatic extent of the disease, due to increased FDG uptake in its malignancy. Even though, FDG is not a tumor-specific agent, FDG-PET is increasingly used. Several authors have reported that FDG-PET has been useful in a diagnostic workup for differentiating among or staging malignant diseases, and monitoring the response to treatment of pulmonary artery intimal sarcoma [4, 5]. Among unusual findings, Mathias et. al.  reported a pulmonary intimal sarcoma with a lack of uptake of FDG in PET. It also revealed highly malignant cells, but its cellularity was low with marked interstitial myxoid tissue. Also in our patient, the FDG uptake was not significant, and we decided that the mass was a thrombus with distal embolic progression. Even though the character of the tumor was highly malignant, if the cellularity was low and myxoid tissue was marked, a negative FDG-PET study would have been possible. The patient mass did not take up FDG significantly in the FDG-PET, and thus we misdiagnosed it as a thrombus. This mistaken diagnosis could have led to inappropriate therapy, such as anticoagulation and thrombolysis. Unfortunately, there were few treatment options and there are no specific guidelines on the management of pulmonary artery sarcomas. The usual therapy is a surgical approach with adjuvant chemotherapy [7, 8]. The prognosis, which depends on the location and vascular extension, is very poor without surgery. The surgical procedures, such as pneumonectomy, palliative stenting, and endarterectomy of the pulmonary artery, depend on the tumor site. Even if patients present with unresectable lesions, debulking surgery might still be needed for hemodynamic improvement. Some cases that have undergone surgery have had a long-term survival of approximately 3 years for isolated local tumors . However, in our patient, both distal pulmonary arteries were completely or partially obstructed with the thrombi. Thus, complete removal of the tumor embolus was impossible, postoperative hemodynamic status was very poor, and ECMO was needed.
Intimal sarcoma of the pulmonary artery is a rare malignant tumor that may be misdiagnosed as pulmonary thromboembolism, even if advanced imaging technology is used. Even though the FDG is poorly taken up in PET, the possibility of malignancy should be considered. We report a case of pulmonary artery intimal sarcoma that was not initially diagnosed as a malignancy due to poor uptake of FDG in a PET study.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
This research was supported by Yeungnam University research grants in 2012.
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