Pulmonary cryptococcosis is a form of pulmonary fungal infection caused by Cryptococcus gattii and C. neoformans. The respiratory tract is the principal route of entry for infection via inhalation of fungal spores.
Cryptococcosis predominantly occurs in immunocompromised patients but can also be seen in immunocompetent hosts, particularly, those exposed to avian (e.g. pigeon) droppings. The spectrum of pulmonary cryptococcosis depends on the host's defenses.
The presentation of pulmonary cryptococcosis can range from asymptomatic nodular disease to severe acute respiratory distress syndrome (ARDS) 3:
- most often, causes several lung nodules or masses +/- cavitation, chiefly in immunocompromised patients
- additionally, consolidation, mediastinal lymphadenopathy, and pleural effusion may also be present.
In the immunocompetent host the pulmonary infections normally are asymptomatic, in contradistinction to the immunocompromised patient, in whom cryptococcal infection is most often symptomatic, and commonly disseminates to the central nervous system, skin, and bones 1.
Overall, approximately one-third of patients are asymptomatic.
Symptoms range from a mild cough and low-grade fever to acute presentation with high fever and severe shortness of breath.
The method of entry is usually by inhalation of cryptococcal particles into the lungs, causing pulmonary infection. Spores are found worldwide in soil contaminated by avian droppings.
Serum cryptococcal antigen (sCRAG) levels are helpful in diagnosis and follow-up.
In general, there are several CT patterns that can be seen:
- clustered nodular pattern: most prevalent 4
- solitary pulmonary nodule or mass with or without cavitation
- scattered nodules
- peribronchovascular consolidation
The most common CT findings in immunocompetent patients with pulmonary cryptococcosis are pulmonary nodules. The nodules are most often multiple, smaller than 10 mm in diameter, and well-defined with smooth margins. The nodules usually involve less than 10% of the parenchyma and tend to be distributed peripherally (up to 65% 16) in the middle and upper zones. Where there are multiple nodules, they are usually bilateral 2. Associated cavitation may be seen in up to 40% of cases 8. Occasionally, unusual presentation such as large cavities may be seen 13.
Cavitations within nodules/masses tends to be more frequently present in immunocompromised patients than in immunocompetent patients 16.
FDG PET-CT may play a complementary role to CT 6 and ~60% of patients show higher FDG uptake than the mediastinal blood pool 4.
Treatment and prognosis
- antifungals such as oral fluconazole or intravenous amphotericin B
- 1. Müller NL, Franquet T, Lee KS et-al. Imaging of pulmonary infections. (2007) ISBN:078177232X. Read it at Google Books - Find it at Amazon
- 2. Lindell RM, Hartman TE, Nadrous HF et-al. Pulmonary cryptococcosis: CT findings in immunocompetent patients. Radiology. 2005;236 (1): 326-31. doi:10.1148/radiol.2361040460 - Pubmed citation
- 3. Kruglikov RI. [Several neurochemical mechanisms of learning and memory]. Izv Akad Nauk SSSR Biol. (6): 902-10. - Pubmed citation
- 4. Song KD, Lee KS, Chung MP et-al. Pulmonary cryptococcosis: imaging findings in 23 non-AIDS patients. Korean J Radiol. 11 (4): 407-16. doi:10.3348/kjr.2010.11.4.407 - Free text at pubmed - Pubmed citation
- 5. Huang CJ, You DL, Lee PI et-al. Characteristics of integrated 18F-FDG PET/CT in Pulmonary Cryptococcosis. Acta Radiol. 2009;50 (4): 374-8. doi:10.1080/02841850902756532 - Pubmed citation
- 6. Hsu CH, Lee CM, Wang FC et-al. F-18 fluorodeoxyglucose positron emission tomography in pulmonary cryptococcoma. Clin Nucl Med. 2003;28 (9): 791-3. doi:10.1097/01.rlu.0000082680.98898.2b - Pubmed citation
- 7. Chang WC, Tzao C, Hsu HH et-al. Pulmonary cryptococcosis: comparison of clinical and radiographic characteristics in immunocompetent and immunocompromised patients. Chest. 2006;129 (2): 333-40. doi:10.1378/chest.129.2.333 - Pubmed citation
- 8. Qu Y, Liu G, Ghimire P et-al. Primary pulmonary cryptococcosis: evaluation of CT characteristics in 26 immunocompetent Chinese patients. Acta Radiol. 2012;53 (6): 668-74. doi:10.1258/ar.2012.110612 - Pubmed citation
- 8. Fox DL, Müller NL. Pulmonary cryptococcosis in immunocompetent patients: CT findings in 12 patients. AJR Am J Roentgenol. 2005;185 (3): 622-6. doi:10.2214/ajr.185.3.01850622 - Pubmed citation
- 9. Zinck SE, Leung AN, Frost M et-al. Pulmonary cryptococcosis: CT and pathologic findings. J Comput Assist Tomogr. 2002;26 (3): 330-4. Pubmed citation
- 10. Haddad N, Cavallaro MC, Lopes MP et-al. Pulmonary cryptococcoma: a rare and challenging diagnosis in immunocompetent patients. Autops Case Rep. 2015;5 (2): 35-40. doi:10.4322/acr.2015.004 - Free text at pubmed - Pubmed citation
- 11. Babu AK, Gopalakrishnan R, Sundararajan L. Pulmonary cryptococcosis: An unusual presentation. Lung India. 2013;30 (4): 347-50. doi:10.4103/0970-2113.120618 - Free text at pubmed - Pubmed citation
- 12. Zhang Y, Li N, Zhang Y et-al. Clinical analysis of 76 patients pathologically diagnosed with pulmonary cryptococcosis. Eur. Respir. J. 2012;40 (5): 1191-200. doi:10.1183/09031936.00168011 - Pubmed citation
- 13. Morita S, Shirai T, Asada K et-al. Pulmonary cryptococcosis presenting with a large cavity. Respirol Case Rep. 2014;2 (2): 61-3. doi:10.1002/rcr2.49 - Free text at pubmed - Pubmed citation
- 14. Lam CL, Lam WK, Wong Y, Ooi GC, Wong MP, Ho JC, Lam B, Tsang KW. Pulmonary cryptococcosis: a case report and review of the Asian-Pacific experience. (2001) Respirology (Carlton, Vic.). 6 (4): 351-5. Pubmed
- 15. Hu Z, Chen J, Wang J, Xiong Q, Zhong Y, Yang Y, Xu C, Wei H. Radiological characteristics of pulmonary cryptococcosis in HIV-infected patients. (2017) PloS one. 12 (3): e0173858. doi:10.1371/journal.pone.0173858 - Pubmed
- 16. Xie LX, Chen YS, Liu SY, Shi YX. Pulmonary cryptococcosis: comparison of CT findings in immunocompetent and immunocompromised patients. (2015) Acta radiologica (Stockholm, Sweden : 1987). 56 (4): 447-53. doi:10.1177/0284185114529105 - Pubmed