Acquired pulmonary artery stenosis is rarely found in adults and is usually caused by extrinsic pulmonary artery or right ventricular outflow tract compression by tumor. Marshall et al reported that teratoma and Hodgkin’s lymphoma were most frequent. Primary mediastinal large B-cell non-Hodgkin’s lymphoma is a rare subtype of large B-cell non-Hodgkin’s lymphoma.
This rare type is reported to have involvements of the surrounding vessels in one-third of patients. However, it is uncommon for mediastinal lymphoma to compress the heart or pulmonary arteries sufficiently to produce murmurs or evidence of haemodynamically significant obstruction. This may be due to the tendency for mediastinal tumors to enlarge laterally, rather than antero-posteriorly.4
In a series of case reports, NHL was responsible for only 9% of cases of extrinsic pulmonary artery compression by tumour.1
The MPA has a large lumen that does not easily cause a stenosis with impeding blood flow.
Therefore, it is very rare that the MPA involvement impedes blood flow with significant haemodynamic impairment as seen in the present case.
1.Marshall ME, Trump DL. Acquired extrinsic pulmonic stenosis caused by mediastinal tumors. Cancer1982;49:1496–9.
2.Popat U,Przepiork D, Champlin R,et al. High-dose chemotherapy for relapsed and refractory diffuse large B-cell lymphoma: mediastinal localization predicts for a favorable outcome. J Clin Oncol1998;16:63–9.
3.Robinson T,Lynch J, Grech E. Non-Hodgkin’s lymphoma causing extrinsic pulmonary artery compression. Eur J Echocardiogr2008;9:577–8
4. Waldhausen JA, Lambardo CR, Morrow AG. Pulmonic stenosis due to compression of the pulmonary artery by an intrapericardial tumour. J Thor Surg 1957;37:679-8