The definitive diagnosis of Pneumocystis carinii pneumonia is -
Its life cycle begins when cysts rupture and release sporozoites, which mature into trophozoites that eventually form cysts. The diagnostic methods for P. carinii pneumonia (PCP) have progressed from open lung biopsy to bronchoalveolar lavage (BAL) and induced sputum analysis . Ref Harrison20th edition pg 1056
Serological test
Chest X-ray
Finding cysts in tissue specimens
) CT scan of thorax
Infection