Pneumocystosis

Pneumocystosis
Other namesPneumocystis jiroveci pneumonia,[1] Pneumocystis pneumonia,[2] PCP, Pneumocystis carinii pneumonia[3]
Pneumocystis jirovecii cysts
SpecialtyInfectious diseases[1]
Symptoms
Complications
Types
CausesPneumocystis jirovecii[1]
Risk factorsPoor immunity, HIV/AIDS[4]
Diagnostic methodMedical imaging, bronchoalveolar lavage, immunofluorescence assay, biopsy[2]
PreventionTrimethoprim/sulfamethoxazole (co-trimoxazole) in high risk groups[7]
MedicationTrimethoprim/sulfamethoxazole (co-trimoxazole)[4]
FrequencyUncommon,[4] 97% in lungs[7]

Pneumocystosis is a fungal infection that most often presents as Pneumocystis pneumonia in people with HIV/AIDS or poor immunity.[1][7] It usually causes cough, difficulty breathing and fever, and can lead to respiratory failure.[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.[5][7] If occurring in the skin, it usually presents as nodular growths in the ear canals or underarms.[3]

It is caused by Pneumocystis jirovecii, a fungus which is usually breathed in and found in the lungs of healthy people without causing disease, until the person's immune system becomes weakened.[7]

Diagnosis is by identifying the organism from a sample of fluid from affected lungs or a biopsy.[3][4] Prevention in high risk people, and treatment in those affected is usually with trimethoprim/sulfamethoxazole (co-trimoxazole).[4][8]

The prevalence is unknown.[7] Less than 3% of cases do not involve the lungs.[7] The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the Second World War.[9]

Signs and symptoms

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Pneumocystosis is generally an infection in the lungs.[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]

Lungs

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Main article: Pneumocystis pneumonia

When the lungs are affected there is usually a dry cough, difficulty breathing and fever, usually present for longer than four weeks.[2][7] There may be chest pain, shivering or tiredness.[8] The oxygen saturation is low.[2] The lungs may fail to function.[4]

Eyes

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Pneumocystosis in eyes may appear as a single or multiple (up to 50) yellow-white plaques in the eye's choroid layer or just beneath the retina.[12] Vision is usually not affected and it is typically found by chance.[12]

Skin

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If occurring in the skin, pneumocystosis most often presents as nodular growths in the ear canals of a person with HIV/AIDS.[3][6] There may be fluid in the ear.[6] Skin involvement may appear outside the ear, usually palms, soles or underarms; as a rash, or small bumps with a dip.[6] It can occur on the face as brownish bumps and plaques.[6] The bumps may be tender and the ulcerate.[3] Infection in the ear may result in a perforated ear drum or destruction of the mastoid bone.[6] The nerves in the head may be affected.[6]

Cause

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Pneumocystosis is caused by Pneumocystis jirovecii, a fungus which is generally found in the lungs of healthy people, without causing disease until the person's immune system becomes weakened.[7]

Risk factors

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Pneumocystosis occurs predominantly in people with HIV/AIDS.[8] Other risk factors include chronic lung disease, cancer, autoimmune diseases, organ transplant, or taking corticosteroids.[8]

Diagnosis

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X-ray and CT of ground glass opacities and pneumothorax in pneumocystis pneumonia

Diagnosis of Pneumocystis pneumonia is by identifying the organism from a sample of sputum, fluid from affected lungs or a biopsy.[4][3] A chest X-ray of affected lungs show widespread shadowing in both lungs, with a "bat-wing" pattern and ground glass appearance.[2][7] Giemsa or silver stains can be used to identify the organism, as well as direct immunofluorescence of infected cells.[3]

Diagnosis in the eye involves fundoscopy.[12] A biopsy of the retina and choroid layer may be performed.[12] In affected liver, biopsy shows focal areas of necrosis and sinusoidal widening.[10] H&E staining show extracellular frothy pink material.[10] Typical cysts with a solid dark dot can be seen using a Grocott silver stain.[10]

Differential diagnosis

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Pneumocystosis may appear similar to pulmonary embolism or adult respiratory distress syndrome.[2] Other infections can present similarly such as tuberculosis, Legionella, and severe flu.[2]

Prevention

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There is no vaccine that prevents pneumocystosis.[8] Trimethoprim/sulfamethoxazole (co-trimoxazole) might be prescribed for people at high risk.[8]

Treatment

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Treatment is usually with co-trimoxazole.[4][8] Other options include pentamidine, dapsone and atovaquone.[2]

Outcomes

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It is fatal in 10-20% of people with HIV/AIDS.[3] Pneumocystosis in people without HIV/AIDS is frequently diagnosed late and the death rate is therefore higher; 30-50%.[3]

Epidemiology

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The exact number of people in the world affected is not known.[7] Pneumocystosis affects lungs in around 97% of cases and is often fatal without treatment.[7]

History

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The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the Second World War.[9] It was then known as plasma cellular interstitial pneumonitis of the newborn.[9]

Pneumocystis jirovecii (previously called Pneumocystis carinii) is named for Otto Jírovec, who first described it in 1952.[2]

References

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  1. ^ a b c d "ICD-11 - ICD-11 for Mortality and Morbidity Statistics". icd.who.int. Retrieved 30 June 2021.
  2. ^ a b c d e f g h i Russell-Goldman, Eleanor; Milner, Dan A.; Solomon, Isaac (2020). "Pneumocystosis". In Milner, Danny A. (ed.). Diagnostic Pathology: Infectious Diseases. Elsevier. pp. 310–313. ISBN 978-0-323-61138-1.
  3. ^ a b c d e f g h i j "Pneumocystosis | DermNet NZ". dermnetnz.org. Archived from the original on 24 July 2021. Retrieved 24 July 2021.
  4. ^ a b c d e f g h i j k l "Orphanet: Pneumocystosis". www.orpha.net. Archived from the original on 24 July 2021. Retrieved 24 July 2021.
  5. ^ a b c d e f g Ioachim, Harry L.; Medeiros, L. Jeffrey (2009). "28. Pneumocystosis lymphadenitis". Ioachim's Lymph Node Pathology (4th ed.). Philadelphia: Lippincott Williams & Wilkins. pp. 156–157. ISBN 978-0-7817-7596-0.
  6. ^ a b c d e f g h i Calonje, J. Eduardo; Grayson, Wayne (2020). "18. Infectious diseases of the skin". In Calonje, J. Eduardo; Brenn, Thomas; Lazar, Alexander J.; Billings, Steven D. (eds.). McKee's Pathology of the Skin, 2 Volume Set (5th ed.). Elsevier. p. 964. ISBN 978-0-7020-6983-3.
  7. ^ a b c d e f g h i j k l m n o "CDC - DPDx - Pneumocystis". www.cdc.gov. 22 January 2019. Archived from the original on 25 July 2021. Retrieved 25 July 2021.
  8. ^ a b c d e f g "Pneumocystis pneumonia | Fungal Diseases | CDC". www.cdc.gov. 1 December 2020. Archived from the original on 26 July 2021. Retrieved 26 July 2021.
  9. ^ a b c Carmona, Eva M.; Limper, Andrew H. (February 2011). "Update on the diagnosis and treatment of Pneumocystis pneumonia". Therapeutic Advances in Respiratory Disease. 5 (1): 41–59. doi:10.1177/1753465810380102. ISSN 1753-4666. PMC 6886706. PMID 20736243.
  10. ^ a b c d Zaki, Sherif R.; Alves, Venancio A. F.; Hale, Gillian L. (2018). "7. Non-hepatotropic viral, bacterial, and parasitic infections of the liver". In Burt, Alastair D.; Ferrell, Linda D.; Hubscher, Stefan G. (eds.). MacSween's Pathology of the Liver (7th ed.). Philadelphia: Elsevier. p. 477. ISBN 978-0-323-50869-8.
  11. ^ O'Malley, Dennis P. (2013). "7.4. Infections: Fungi". Atlas of Spleen Pathology. Springer. pp. 151–155. ISBN 978-1-4614-4671-2.
  12. ^ a b c d e Papaliodis, George N. (2017). "9. Pneumocystis jirovecii". In George N. Papaliodis (ed.). Uveitis: A Practical Guide to the Diagnosis and Treatment of Intraocular Inflammation. Springer. p. 71. ISBN 978-3-319-09125-9.
  13. ^ Gigliotti, Frances; Wright, Terry W. (2008). "13. Pneumocystosis". In Hospenthal, Duane R.; Rinaldi, Michael G. (eds.). Diagnosis and Treatment of Human Mycoses. Totowa, New Jersey: Humana Press. ISBN 978-1-59745-325-7.
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