What does right pleural reaction mean in chest x_ray?

Inflammation: There is inflammation between the lung and the chest wall. It can be caused by infection - viral or bacterial or other inflammatory process. Blood clots in the lung and even cancer can cause this reaction but this is rare unless you are at specific risk. Either way you should have your xray repeated in about 2 months to see if it resolves. If painful or trouble breathing see MD promptly.

Consult physician: Can be either pleural thickening (lining of lung) or fluid in pleural space. This can be reaction to infection (viral pleuritis or bacterial etiology, and trauma. Sometimes pleural effusions can be associated with neoplastic processes. All of these things depend on context radiograph was performed; fever, chest pain etc. You should consult person ordering this exam.