Why would someone with pneumocystis jiroveci pneumonia have purple spots on body?

Could be other cause: Patients with pneumocystis jirovecii pneumonia can be very sick & develop other complications such as sepsis. Many of them have other underlying disorders or immune system compromise (such as HIV or transplant related immunosuppression) which puts them at risk for severe sepsis. Those purple spots may be related to their critical illness & not due to pneumocystis jirovecii itself.

HIV: Persons with pneumocystis infection are usually immunosuppressed, and the most common cause is hiv/aids. These patients may also have a type of cancer of the skin caused by herpesvirus 8 called kaposi's sarcoma, and this produces purple skin lesions.