Pulmonary Cryptococcosis: A case report and review of literature.

Introduction

Pulmonary Cryptococcosis is an uncommon lung infection [1] caused by the pathogenic species complex of Cryptococcus neoformans. All 11 sub-species of the complex are yeast-like encapsulated saprophytic basidiomycetes [2&3].

Cryptococcus neoformans is an occasional opportunistic fungal so although it’s relatively inactive in immunocompetent patients, it can cause very serious complications in immunosuppressed patients, including fatal meningitis - meningoencephalitis (mortality rate is 10-30% [5]), as well as severe pneumonia which is one of the leading mycological causes of morbidity/ mortality among HIV patients worldwide [1&6].

However, as previously said, immunocompetent hosts usually do not experience any symptoms and if they do, those symptoms are relatively mild. Also, the study of sign and symptoms of the disease is at a relatively early stage. Those 2 factors are detrimental to the fact that a great percentage of such cases are misdiagnosed as other diseases, such as lung cancer [6].

The reason lung cancer is one of the main misdiagnoses clinicians make, is because the radiography of the chest indicates the presence of nodular or mass-like lesions in the lungs. It is therefore easy yet obviously wrong to assume those lesions as malignant [1&6].

The proper diagnosis of this infection employs chest X-rays and computed tomographic (CT) scans to detect the the nodular or mass-like lesions in combination with tissue biopsy and culture to identify the specific type of microorganism, before jumping to conclusions on the nature of the cells inside the lesion [5&6]

Alternatively, in order to properly explain the presence of such lesions, we have to also utilize histopathological methods. This is because just by analyzing the radiography, we cannot differentiate whether the presence of the lesions is due to malignancy or not. Also, even if we somehow knew that the cells of the lesions were not cancerous, we still couldn’t specify the infections and thus, we wouldn’t proceed with the optimal disease management plans [5&6].

On a more general scale, histopathology enables experts to explore changes in cells that can clarify the real cause of the patient’s illness. Pathologists are able to reach a conclusion for their diagnosis, just by examining a little piece of tissue from various organs [7].

Therefore, histopathology is extremely important because it broadens and advances the treatment options [7].

Materials and Methods

Patient’s Clinical History

The patient is a 59 year-old male which currently travels through his post-orthotopic-liver-transplant (due to HCV) period. Patient resides in Pennsylvania, where the general climate is temporal. Patient is also a light smoker. After the liver transplant, patient appeared with an overall increase in the values of the liver function tests, as well as a decrease in his body weight. He was then admitted to the hospital where the following conclusions were deduced: stable vital signs, afebrile, ordinary lung function (auscultation), great overall abdominal image and no signs of adenopathy. Clinicians proceeded with a routine CT scan of his chest, in which four nodular lesions were observed, within the peripheral aspect of the left upper lobe. Again, no signs of adenopathy were noted in any of the examining regions.

Methodology

[After the radiographic scans, CT-guided fine needle aspiration of the left upper lobe mass was performed]

Through a careful and thorough observation and examination of the panel images on the Figure 2 and Figure 3, we came in the following conclusion regarding the methods and the techniques used to acquire those panel images:

The images were captured by a light microscope with the help of histochemistry. We can clearly observe the colouring of the tissue and thus we can assume tissue staining. Specifically, the staining materials ranged from PAS to possibly H&E and ultimately, mucicarmine which is widely for the detection of C. neoformans fungi.

From the fact that the above techniques were used to find out the presence of malignancy or fungi, we can rationally assume that the procedure that was executed to obtain the corresponding samples was CT-guided fine needle aspiration.

CT-guided FNA is a type of biopsy procedure, in which a very thin needle is inserted into the “abnormal” area -in this case the lobe mass- and a tissue sample is extracted and placed into smear aspirator and from there, it is sent to the laboratory for further analysis. It’s most usually used to rule out conditions such as cancer.

The diagnostic yield of FNA in these cases has been shown to be higher than that of bronchoscopy with biopsy and many other techniques, and that’s why we can assume that the images were obtained using with this method.

Finally, note that histological sections are almost transparent, and stains are used to utilized to recognize individual components of cells. However, Immunohistochemistry uses antibodies labelled coloured dyes, which are then used as specific test modes, to locate specific protein molecules to individual cells in tissue sections, and this study is irrelevant at our case.

Results

Computed tomography scan of his chest demonstrated four nodular lesions within the peripheral aspect of the left upper lobe, the largest measuring 3x3cm. A small left pleural effusion was also noted, however, no adenopathy was identified within the axillary regions, mediastinum, or hilar regions.

Computed tomography guided FNA of the left upper lobe mass was performed.

Cytologic examination of direct smears of FNA material obtained from the left upper lobe mass revealed a slightly mucoid background, moderate cellularity, polymorphonuclear leukocytes, lymphocytes, and epithelioid histiocytes (figure 2).

Also, a significant number of spherical to ovoid yeast forms were seen which appeared to have a capsule. Several of the organisms exhibited narrow-based budding. Mucicarmine stain highlighted the capsular material (figure 3).

Figures

Figure 1: The figure represents the CT scan of the patient’s chest. We can clearly observe the presence of relatively big nodular lesion on the (upper) left lobe. However, there are another 3 nodular lesions which are not clearly captured in this image

Figure 2: This figure represents histological tissue samples obtained from the lobe mass (both panels are PAS stained). (A) Deep red colour (magenta) demonstrates the presence of mucus. (B) The bluish colour in the 2nd panel demonstrates yeasts morphology.

Figure 3: This figure represents histological tissue samples obtained from the lobe mass (1st panel is PAS stained but the 2nd can be both PAS and H&E stained). (A) Green circles clearly indicate the presence of narrow-based budding yeasts (B) The toned purple border in the 1st panel indicates the presence of capsular material (C) The 2nd panel is also stained with mucicarmine, in order to emphasize the characteristic gelatinous capsule with a bright pink.

Discussion

Diagnosis

“Cytologic examination of direct smears of FNA material obtained from the left upper lobe mass revealed a slightly mucoid background, moderate cellularity, polymorphonuclear leukocytes, lymphocytes, and epithelioid histiocytes (Figure 2).”

The presence of high amount of immune cells (leukocytes , lymphocytes, histiocytes) in the specific are (left upper lobe), indicate the presence of an infection or injury for which the immune cells are getting concentrated.

Looking at the clinical image of the patient and the above information, we can exclude the presence of an injury (non-mentioned). We can then exclude a number of infections which cause inflammation because the patient was afebrile (ex. pneumonia bronchitis). We can also semi-exclude a number of infections which usually have an effect on the heart, because the patient showed regular rate and rhythm (ex. Influenza virus). Finally, we can semi-exclude adenopathy related diseases as we assume no abnormal lymph nodes were palpated during the physical examination of the patient.

“Also, a significant number of spherical to ovoid yeast forms were seen which appeared to have a capsule. Several of the organisms exhibited narrow-based budding. Mucicarmine stain highlighted the capsular material (Figure 3).”

The presence of encapsulated spherical/ ovoid shaped yeasts combined of the observation of narrow-based budding, clearly narrows down the potential infectious agent to a complex of species: Cryptococcus neoformans.

That is because out of the kingdom of fungi the complex of C. neoformans have the distinct following characteristics, polysaccharide capsule and replication via narrow-based budding.

Finally, the histological findings in are quite specific to this disease, yet they cannot identify which one of the species was the infectious agent, because both C neoformans species complex and C gattii exhibit a similar morphology. However, pulmonary infection is rarely caused by C gattii, and only a few cases were reported [6].

Pulmonary Cryptococcosis

Cryptococcosis is a common opportunistic infection in acquired immunodeficiency syndrome (AIDS) patients and in other immunosuppressed patients and significantly more uncommon to those with no apparent immunocompromise. Most infections with C. neoformans occur in the lungs. However, meningitis and encephalitis are often caused by C. neoformans, making it a particularly dangerous fungus [6].

Most of the cases are caused by the ubiquitous encapsulated yeast, C. neoformans, whereas, as mentioned, C. gatti accounts for a smaller proportion of cases, often in immunocompetent patients. It is an intracellular pathogen that can utilize phagocytes of the host to spread within the body [8].

In the human lungs, C. neoformans cells are phagocytosed by local macrophages. Those macrophages produce toxic agents, in order to create a hostile environment, to kill the invading pathogens. However, some C. neoformans cells can survive intracellularly in macrophages, with the help of their capsule. "Intracellular survivors” appears to be the fundamental brick for latency, disseminated disease, and resistance to eradication by antifungal agents [9].

In our case, the patient is currently traveling a time period after which he had a liver transplant due to sever hepatitis C and thus, he receives immunosuppressant drugs on a weekly basis, in order for his body to accept the donor’s liver [6].

That’s exactly why our patient falls under the “immunocompromised” category of patients and is susceptible to opportunistic infections such as (pulmonary) cryptococcus [7].

Pulmonary Cryptococcosis Management

Factors predisposing to cryptococcal infection include corticosteroid administration, lymphoreticular malignancies (especially Hodgkin's disease), sarcoidosis and HIV infection (80-90%); however, 50% of cases have no recognized predisposing condition [manual].

Temperate climates, exactly like Pennsylvania which our patient lives in, are the primary location for Cryptococcus neoformans var. neoformans [manual]. Thus, we not only identify a potential cause of the disease, but we can conclude that the disease was caused by this very specific variety of the complex.

“Initial therapy of pulmonary disease should be amphotericin B alone or in combination with flucytosine. Amphothotercin B can be administered alone for 6-10 weeks or in conjunction with flucytosine for 2 weeks, followed by fluconazole for a minimum of 10 weeks.” [11]

References

1. Kanet Kanjanapradit,1 Zdravko Kosjerina,2 Wiwatana Tanomkiat,3 Warangkana Keeratichananont,4 and Siripen Panthuwong, 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5546643/

2. [FerryHagenabKantaraweeKhayhanacBartTheelenaAnnaKoleckaaItzhackPolacheckdEdwardSionovdeRamaFalkdfSittipornParnmeng ThorstenLumbschhTeunBoekhout](https://www.sciencedirect.com/science/article/pii/S1087184515000328?via%3Dihub#!), 2009, https://www.sciencedirect.com/science/article/pii/S1087184515000328?via%3Dihub#s0145

3. Gustavo de Sousa Arantes Ferreira, Andre Luis Conde Watanabe, Natalia de Carvalho Trevizoli, Fernando Marcus Felippe Jorge, Carolina de Fatima Couto, Priscila Brizolla de Campos, and Gabriel Oliveira Nunes Caja, 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7280860/

4. Joel Schop, 2007, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2323542/

5. Unknown author, 2012, https://en.wikipedia.org/wiki/Cryptococcus_neoformans

6. Kanet Kanjanapradit,Zdravko Kosjerina, Wiwatana Tanomkiat, Warangkana Keeratichananont, and Siripen Panthuwong2007, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5546643/

7. Unknown author, 2009, https://anapath.ch/things-to-know-about-histopathology/

8. Assoc Prof Patrick Emanuel, 2017, https://dermnetnz.org/topics/cryptococcosis-pathology

9. Unknown author, 2006, https://webpath.med.utah.edu/LUNGHTML/LUNG503.html

10. Findra Setianingrum, Riina Rautemaa-Richardson, David W Denning, 2003, https://academic.oup.com/mmy/article/57/2/133/5133472

11. Unknown author, unknow date, https://www.medscape.com/register?client=205502&scode=msp&action=complete&lang=en&register=true&form=about&urlCache=aHR0cHM6Ly9lbWVkaWNpbmUubWVkc2NhcGUuY29tL2FydGljbGUvMjE1MzU0LXRyZWF0bWVudA