Primary pulmonary artery leiomyosarcoma

Primary pulmonary artery leiomyosarcoma is a form of thoracic sarcoma and an extremely rare tumor of the thorax.

Epidemiology

The reported incidence rate is very low at around  ~0.001-0.03%. Most patients are around 40 and 60 years at time of diagnosis. 

Pathology

They are a smooth muscle tumor and are thought to arise from pluripotent cells found in the intima of the vessel. They may account for around 20% of all primary pulmonary artery sarcomas ⁷.

Clinical presentation

Symptoms are often non-specific and include cough, exertional dyspnea, chest pain, right ventricular failure and therefore can be misinterpreted as being related to pulmonary embolism. Diagnosis can often be delayed.

Radiographic features

CT

May be seen as a unilateral mass continuously filling the pulmonary artery with inhomogenous, heterogenous enhancement. Features of vascular distension, extravascular invasion into adjacent structures may be present.

MRI

Useful for assessing presence of enhancement.

• T1 C+ (Gd): shows enhancement or areas of enhancement ¹³

FDG-PET

May show uptake in the area of tumor ⁸.

Treatment and prognosis

It is an extremely malignant tumor with median survival times of all patients according to one publication of around 1.5 months with possible prolonged to 10 months with surgery such as pneumonectomy +/- excision of the tumor from the vascular bed. Early detection and surgical resection improves patient survival, the benefits of adjuvant therapy are not well understood. Systemic metastases have been reported in around 20% of cases at diagnosis and sites include the liver, pancreas, mesentery, brain, adrenals, kidneys, thyroid and the skin ⁹. Frequency of metastatic disease is not thought to be related to original tumor size,

Differential diagnosis

Consider

• primary pulmonary angiosarcoma
• large occlusive pulmonary embolus ^2,12
• it may very rarely mimic disseminated tuberculosis ⁹

See also

• leiomyosarcoma
• pulmonary artery sarcoma