Pneumocystosis

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Pneumocystosis
Other names: Pneumocystis jiroveci pneumonia,[1] pneumocystis pneumonia,[2] pneumocystis carinii pneumonia (PCP)[3]
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Pneumocystosis on chest X-ray
SpecialtyInfectious diseases[1]
Symptoms
ComplicationsRespiratory failure, perforated ear drum[4][6]
Types
CausesPneumocystis jirovecii[7]
Risk factorsPoor immunity, HIV/AIDS[4]
Diagnostic methodMedical imaging, bronchoalveolar lavage, immunofluorescence assay, biopsy[2]
PreventionTrimethoprim/sulfamethoxazole (co-trimoxazole) in high risk groups[8]
MedicationTrimethoprim/sulfamethoxazole (co-trimoxazole)[4]
Prognosis10 to 50% risk of death[2]
FrequencyUncommon,[4] 97% in lungs[7]

Pneumocystosis is a fungal infection that usually presents as pneumonia.[7] Symptoms may include cough, difficulty breathing and fever, and can lead to the lungs to stop working.[4] Involvement outside the lungs is rare, but may include lymph nodes, spleen, liver, bone marrow, kidneys, thyroid, and other organs.[5][7] In the skin, it may present as nodular growths in the ear or underarms.[3]

It is caused by the fungus Pneumocystis jirovecii.[7] It generally only occurs in people with poor immunity such as HIV/AIDS or premature babies.[7][1] It is an airborne disease.[4] It is often breathed in by 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 tissue biopsy.[3][4] Prevention in high risk people, and treatment in those affected is usually with trimethoprim/sulfamethoxazole (co-trimoxazole).[4][8] There is no vaccine.[8] Between 10 to 50% of those infected die as a result.[2]

Pneumocystosis has a worldwide distribution.[2] The precise number of people affected is unknown.[4] More than 97% of cases only involve the lungs.[7] The first cases were described in premature and malnourished babies in Europe following the Second World War.[9]

Signs and symptoms

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

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

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

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 skin may break.[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

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

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] It has been reported in premature infants and malnourished children.[2]

Diagnosis

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 frothy pink material outside cells.[10] Typical cysts with a solid dark dot can be seen using a Grocott silver stain.[10]

Differential diagnosis

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

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

Treatment

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

Outcomes

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

Pneumocystosis has a worldwide distribution.[2] 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 if not treated.[7]

The liver may be affected by pneumocystosis in up to 40% of HIV-positve people with CD4+ T-lymphocyte counts of <50/mm3, who have been given pentamidine by inhalation.[10]

History

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

  1. 1.0 1.1 1.2 "ICD-11 - ICD-11 for Mortality and Morbidity Statistics". icd.who.int. Archived from the original on 1 August 2018. Retrieved 30 June 2021.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 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. Archived from the original on 2021-07-28. Retrieved 2021-07-28.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 "Pneumocystosis | DermNet NZ". dermnetnz.org. Archived from the original on 24 July 2021. Retrieved 24 July 2021.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 "Orphanet: Pneumocystosis". www.orpha.net. Archived from the original on 24 July 2021. Retrieved 24 July 2021.
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 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. Archived from the original on 2021-07-27. Retrieved 2021-07-26.
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 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. Archived from the original on 2021-07-25. Retrieved 2021-07-24.
  7. 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 7.11 7.12 7.13 7.14 7.15 "CDC - DPDx - Pneumocystis". www.cdc.gov. 22 January 2019. Archived from the original on 25 July 2021. Retrieved 25 July 2021.
  8. 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 "Pneumocystis pneumonia | Fungal Diseases | CDC". www.cdc.gov. 1 December 2020. Archived from the original on 26 July 2021. Retrieved 26 July 2021.
  9. 9.0 9.1 9.2 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. Archived from the original on 2021-07-25. {{cite journal}}: |access-date= requires |url= (help)
  10. 10.0 10.1 10.2 10.3 10.4 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. Archived from the original on 2021-07-27. Retrieved 2021-07-26.
  11. O'Malley, Dennis P. (2013). "7.4. Infections: Fungi". Atlas of Spleen Pathology. Springer. p. 151-155. ISBN 978-1-4614-4671-2. Archived from the original on 2021-07-27. Retrieved 2021-07-26.
  12. 12.0 12.1 12.2 12.3 12.4 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. Archived from the original on 2021-07-27. Retrieved 2021-07-27.
  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. Archived from the original on 2021-07-27. Retrieved 2021-07-26.

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