CT scans may detect a soft tissue density located in or around the pulmonary arteries. Differentiating thrombus from sarcoma is difficult, unless there is evidence of tumor elsewhere. Head, chest and abdominal CT should be obtained to rule-out distant metastases. Bronchoscopy and biopsies are usually nondiagnostic, but may be helpful. The perfusion defects are indistinguishable from pulmonary embolism.
Serial scans show no resolution despite anticoagulation, signaling another cause.
Pulmonary angiograms are useful to confirm occlusion of the pulmonary arteries and to delineate the size and location of the lesion. Angiography can also be used to obtain a histological diagnosis by an endocardial biopsy. Initially patients are often treated with anticoagulants because of the misdiagnosis of pulmonary embolism. These observations should suggest another cause of the pulmonary arterial obstruction. The spindle cells typically have abundant cytoplasm and centrally located nuclei.