[4] Involvement outside the lungs is rare but, can occur as a disseminated type affecting lymph nodes, spleen, liver, bone marrow, eyes, kidneys, thyroid, gastrointestinal tract or other organs.

[7] The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the Second World War.

[4] Involvement outside the lungs is rare but, can occur as a disseminated type affecting lymph nodes, bone marrow,[5][7] liver[5][10] or spleen.

[5][11] It may also affect skin,[3] eyes,[12] kidneys, thyroid, heart, adrenals and gastrointestinal tract.

[5][13] When the lungs are affected there is usually a dry cough, difficulty breathing and fever, usually present for longer than four weeks.

[12] If occurring in the skin, pneumocystosis most often presents as nodular growths in the ear canals of a person with HIV/AIDS.

[6] Skin involvement may appear outside the ear, usually palms, soles or underarms; as a rash, or small bumps with a dip.

[8] Diagnosis of Pneumocystis pneumonia is by identifying the organism from a sample of sputum, fluid from affected lungs or a biopsy.

[2][7] Giemsa or silver stains can be used to identify the organism, as well as direct immunofluorescence of infected cells.

[12] In affected liver, biopsy shows focal areas of necrosis and sinusoidal widening.