1. Case of the Month 19 January 2017
History:
A 56-year-old farmer with no known previous disease presented with progressive shortening of breath and hemoptysis. An initial chest radiograph was performed, followed by a CT for exclusion of pulmonary embolism.

2. Case of the Month 19

3. Case of the Month 19
What is your diagnosis ?

5. Case of the Month 19 January 2017
History:
A 56-year-old farmer with no known previous disease presented with progressive shortening of breath and hemoptysis. An initial chest radiograph was performed, followed by a CT for exclusion of pulmonary embolism.
What are the key findings on the CXR?

6. Case of the Month 19
The chest x-ray demonstrates an enlarged left pulmonary artery with mass lesions in the periphery of the left lung base. There is also a small left pleural effusion.

7. Case of the Month 19
CT demonstrates a complete occlusion of the left lower lobe and lingula arteries which at first sight gives an impression like pulmonary embolism. But there is an expansive effect of the lesion and some spiculation around some vessels (blue arrow), suggestive of infiltration, which is not compatible with pulmonary embolism. Furthermore, the subpleural lesions, which are located in the periphery of the occluded vascular territories look like nodular mass lesions and do not have the pattern of pulmonary infarction. No emboli were present on the right side. Therefore, we suspected a neoplastic occlusion of the vessel with peripheral tumor emboli and pulmonary metastases.

8. Case of the Month 19
A PET-CT demonstrated 18FDG-uptake in the occluded pulmonary vessels, in an enlarged mediastinal lymph node and the subpleural nodular lesions. A core biopsy of one of the subpleural nodular lesions was perfomed. Histology demonstrated a spindle cell sarcoma. Therefore, the diagnosis of a spindle cell sarcoma of the left pulmonary artery with mediastinal and intrapulmonary metastases was made.
Case provided by Dr M. Müller
Frauenfeld, Switzerland

9. Case of the Month 19 Discussion
Pulmonary artery sarcomas are rare, representing less than 1% of all sarcomas
They typically occur in middle-aged adults and the clinical symptoms depend on their location
They are asymptomatic or can manifest as hemoptysis, chest pain, dyspnea or heart failure
The imaging diagnosis can be delayed due to misinterpretation of the findings as pulmonary embolism

10. Case of the Month 19 Discussion
Imaging features which should raise concern about the presence of a neoplasm rather than a simple embolus are:
Large unilateral obstruction of the main pulmonary arteries,
Vascular distension
Expansion beyond the vessel wall
Lack of improvement despite adequate anticoagulation
No evidence of a deep venous thrombosis and
Distant metastases
MR imaging or PET can be useful, because they can show enhancement or 18FDG uptake. However, the enhancement on MR can be subtle and standard MDCT usually shows no enhancement.

11. Case of the Month 19 Discussion
Pulmonary artery sarcomas commonly rise from the pulmonary trunk and the central pulmonary arteries
The most dominant histologic subtypes are undifferentiated intimal sarcoma and leiomyosarcoma
The treatment consists, when possible, of surgical resection, radiation and chemotherapy
Adenopathies or metastases are poor prognostic indicators with a 5-year survival rate of less than 20% (with spindle cell histology)

12. References and recommended further reading
Case of the Month 19
References and recommended further reading
von Falck C, Meyer B, Fegbeutel C et al. Imaging features of primary Sarcomas of the great vessels in CT, MRI and PET/CT: a single center experience. BMC Medical Imaging 2013; 13:25 (
Gladish GW, Sabloff BM, Munden RF et al. Primary Thoracic Sarcomas. Radiographics 2002; 22:
Bressler EL, Nelson JM. Primary Pulmonary Artery Sarcoma: Diagnosis with Imaging, and Transthorcacic Needle Biopsy. AJR 1992; 159: