Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Primary spontaneous pneumothorax ?
    ### Response:
    Primary spontaneous pneumothorax is an abnormal accumulation of air in the pleural space (the space between the lungs and the chest cavity) that can result in the partial or complete collapse of a lung. It is called primary because it occurs in the absence of lung disease such as emphysema and spontaneous because the pneumothhorax was not caused by an injury such as a rib fracture.
    