Pneumocystis Jirovecii Pneumonia in Newly Diagnosed HIV Infection: A Challenging Case Report
Selin KESTEL KAYIK, Elif ACAR, Leyla MEMİŞ
Department of Pathology, Gazi University, School of Medicine, ANKARA, TURKEY
Keywords: Acquired Immunodeficiency Syndrome, Pneumocystis pneumonia, HIV
Pneumocystis jirovecii is a potentially life-threatening opportunistic pathogen particularly affecting the lungs, mainly in immunosuppressed
individuals and HIV-infected patients with a low CD4 cell count. A 50-year-old man presented with a 1-week history of pleuritic chest pain
and fever. He was also hypoxic with oxygen saturation of 86% on room air. Detailed clinical history revealed that he had fatigue, dyspnea, night
sweats, generalized bone pain and a loss of about 10 kg in weight over the past six months without intention. Chest imaging showed diffuse
bilateral infiltrates. Diagnostic bronchoscopy was performed. Transbronchial biopsy and bronchoalveolar lavage were received simultaneously.
The presence of P. jirovecii was suspected in hematoxylin-eosin-stained slides, and Gomoris methenamine silver stain was used to confirm the
diagnosis. A blood test revealed dyslipidemia, hypothyroidism, increased plasma levels of the gonadotropins and positive HIV antibodies with
a CD4+ cell count of 48/μL. CMV co-infection was found with CMV viral load of 6738 copies/ml in plasma. Herein, we present a case with
Pneumocystis jirovecii pneumonia (PCP) that led to a new diagnosis of Human immonudeficiency virus. As in our case, diagnosis of disease
through the pathological examination of tissues (biopsy samples) or bodily fluids could lead to the recognition of an unrevealed HIV-infection.
The incidence of AIDS and patients infected with HIV have
greatly increased in number since the 1980s. Pneumocystis
pneumonia quickly became one of the main AIDS-defining
diseases in the late 1980s 1
. There are currently 37.9
million people living with HIV. 1.7 million people were
newly infected with HIV in 2018 and 770,000 people died
of AIDS-related illnesses 2
Pneumocystis was first recognized in an animal that was
infected with Trypanosoma cruzi. It was therefore thought
that Pneumocystis was a form in the life cycle of T. cruzi.
The one who first recognized Pneumocystis in the lungs of
an experimentally infected rat with T. Lewisi was Antonio
Carinii. This new species of Pneumocystis was named P.
carinii and caused infection in rat lungs. Pneumocystis was
also described as the causative agent of interstitial plasma
cell pneumonia in the lungs of premature debilitated babies
in nurseries and foundling hospitals in Central Europe by
Van der Meer and Brug in 1942 3. However, the most
convincing evidence was established by Vanek and Jirovec
in 1952. Vanek and Jirovec identified Pneumocystis as the
causative agent of this disease from autopsies of 16 cases
4. Firstly Pneumocystis was accepted as protozoa, but
then it was proved by DNA analysis that Pneumocystis is a close relative of fungi rather than protozoa 5. The
Pneumocystis organisms which infect humans are named
P. jirovecii. Impairment of cell-mediated immunity is
especially important for the development of PCP. This
relationship is proved by the co-occurrence of PCP in
patients with AIDS. Other common populations that are
under the risk of developing PCP are organ transplant
patients, cancer patients, and patients on chemotherapeutic
agents and immunosuppressant drugs such as steroids,
cytotoxic agents and anti-tumor necrosis factor drugs used
for rheumatologic diseases 6.
We describe a case with Pneumocystis pneumonia and
newly diagnosed Human Immunodeficiency Virus in a
patient with nonspecific symptoms. Besides PCP, a detailed
examination revealed endocrine abnormalities with an
untreated advanced HIV infection at first admission.
A 50-year-old man presented with a 1-week history of
pleuritic chest pain and fever. His body temperature was
38.4 °C. He was also hypoxic with oxygen saturation
of 86% on room air, requiring 3-4 L of oxygen per nasal
cannula. The detailed clinical history revealed that he
had fatigue, dyspnea, night sweats, generalized bone pain and an unintentional loss of about 10 kg in weight over
the past six months. He has no known disease or surgical
operation history. He did not use any medication. Physical
examination was noteworthy for basal rales bilaterally.
Laboratory examinations showed an elevated ESR 102
mm/hr (normal reference 1-15 mm/hr), CRP 79.6 mg/L
(normal reference 0-5 mg/L), ProBNP 171 pg/mL (normal
reference 0-110 pg/mL), TSH 10,604 mIU/mL (normal
reference 0.38-5.33 mIU/mL), antithyroglobulin antibodies
5.7 IU/mL (normal reference 0-4 IU/mL), FSH 27.14 mIU/
mL (normal reference 1.27-19.26 mIU/mL), LH 13.47
mIU/mL (normal reference 1.24-8.62 mIU/mL), LDL 137.9
mg/dL (normal reference 60-130 mg/dL), total cholesterol
216.6 mg/dL (normal reference 0-200 mg/dL), HDL 30.7
mg/dL (normal reference 40-60 mg/dL), triglycerides 240
mg/dL (normal reference 0-200 mg/dL) and low levels of
Hemoglobin at 10.8 g/dL (normal reference 13.5-17.5 g/dL).
WBC count was 8.06×109/L (normal reference 4.5 to 11.0
×109/L). A chest X-ray showed diffuse bilateral infiltrates
). Firstly, the patient was started empirically
with ceftriaxone and clarithromycin for a presumed
diagnosis of infection, and prednisone for respiratory
distress. Diagnostic bronchoscopy with bronchoalveolar
lavage and transbronchial biopsy was done for etiological
investigation. Light microscopic examination of the
transbronchial biopsy showed foamy, pale eosinophilic,
amorphous material in the alveolar spaces (Figure 2
Next to these areas, the thickness of the alveolar septum
was increased with lymphoplasmacytic inflammatory cell
infiltration. A predominance of type 2 pneumocytes was noticed in the alveolar walls (Figure 2
). The differential
diagnostic list included pulmonary alveolar proteinosis,
alveolar edema, and Pneumocystis jirovecii pneumonia.
Alveolar proteinosis was excluded since there were no
cholesterol clefts and PAS-positivity in the intra-alveolar
material. With Gomoris methenamine silver nitrate
method, cysts of Pneumocystis jirovecii stained brownishblack
with capsular dots (Figure 3
Click Here to Zoom
|Figure 1: Bilateral diffuse symmetric reticular interstitial
Click Here to Zoom
|Figure 2: An alveolus with the foamy/bubbly eosinophilic
exudates and a few mononuclear cells. The alveolar septa have a
few inflammatory cells and collagen and are lined by hyperplastic
type II pneumocytes (H&E; x600).
Click Here to Zoom
|Figure 3: Gomori Methenamine-Silver (GMS) stain of
transbronchial biopsy shows Pneumocystis jirovecii cysts with
capsular dots. Note that the position of the dots varies in each cyst
Click Here to Zoom
|Figure 4: The foamy/bubbly eosinophilic exudates and a few
mononuclear cells in the bronhoalveolar lavage fluid cell block
(H&E; x600). Inset image: GMS stain decorates the crescentic cyst
walls within the foamy material (GMS; x1000).
HIV antibody testing was performed, and the patient tested
positive. The CD4 count was 48 cells/μm (normal reference
range 500-1500 cells/μm) and viral load was very high (1
260 000 copies). CMV co-infection was found with CMV
viral load of 6738 copies/ml in plasma.
The patient has been followed up for two years and had
two episodes of CMV pneumonia plus one of Pneumocystis
HIV infection is closely related to opportunistic infections
and tumors that are mostly seen in immunosuppressed
individuals. In the acute phase of HIV infection, CD4+ T
cells in mucosal tissue are infected 7
. Mucosal infection
is followed by the dissemination of the virus and the
development of antiviral humoral and cell-mediated
host immune responses. These responses are evidenced
by seroconversion that is usually detectable within 3 to 7
weeks of presumed exposure. In this stage, 40% to 90%
of people who acquire a primary infection develop acute
retroviral syndrome. Clinically it is a self-limited acute
illness with nonspecific symptoms such as sore throat, myalgias, fever, weight loss, and fatigue, resembling a flulike
illness. These clinical findings resolve spontaneously
in 2 to 4 weeks. During this period, major transmission of
infection can happen even before the antibody response
has appeared 8
. If individuals have tissue biopsies in this
period, it is possible to detect HIV by immunochemistry
. In the chronic phase of the HIV infection, patients
are either asymptomatic or develop minor opportunistic
infections such as oral candidiasis, vaginal candidiasis
or herpes zoster. Finally, when the host defense loses the
battle, a dramatic increase in the plasma viral load and lifethreatening
severe clinical HIV disease appears, originally
termed as acquired immune deficiency syndrome (AIDS)
Pneumocystis is an extracellular organism that has a major
predilection for the lung and mostly inhabits alveolar
spaces 11. P. jirovecii is still the most common cause of
lethal pneumonia in patients with HIV infection. Although
it is not certain, the transmission of Pneumocystis from
host to host is assumed to occur via aerosolized particles
12. Pneumocystis organisms have at least 2 predominant
life cycle forms. The trophic form measures between 1-4
μm, is relatively pleomorphic in shape, is found in clusters,
is surrounded by a plasma membrane, and has no rigid
cell wall. For detection of the trophozoite form, a variety
of Romanowsky stains (Giemsa, Wright, Diff-Quick),
and Gram and methylene blue stains can only be applied
to imprint smears and cytology specimens 13. The cyst
form is 5 to 7 μm in diameter, appearing as thick-walled
spherules. When collapsed, the cyst form looks like a cup or crescent shape, contains up to eight intracystic bodies. The
cyst wall-stains can be used for tissue sections and include
Gomoris (Grocott) methenamine silver (GMS) and its rapid
variants, toluidine blue O, and Gram-Weigert methods.
GMS is mostly preferred for daily routine diagnostic work
by pathologists. We also used GMS to observe P. jirovecii
in our case (Figure 3,4). For diagnostic purposes, various
methods can be used. The output of these diagnostic
specimens according to Gigliotti & Limper & Wright,
2014 is approximately as follows; induced sputum 20-40%,
tracheal aspirate 50-60%, bronchoalveolar lavage 75-95%,
transbronchial biopsy 75-95%, and open lung biopsy 90-
100% 3. In immunocompromised patients, especially
those with impaired CD4+ T cell function, pneumocystis
organisms begin to proliferate in alveolar spaces and
cause fatal infection if untreated. The key inflammatory
cells which evoke inflammation in Pneumocystis infection
include CD4+ T cells, alveolar macrophages, and
neutrophils. Type 1 pneumocyte degeneration, hyperplasia
of type 2 pneumocytes, and impairment of the alveolarcapillary
barrier are observed during advanced infection. As
a result, the alveolar gas exchange is disrupted. Surfactant
dysfunction is also observed in P. jirovecii pneumonia
The typical histopathological pattern in PCP in the
individual with AIDS includes eosinophilic, foamy exudate
in the alveolar lumen which contains cell debris and the
microorganisms (Figure 2). The alveolar exudate may
be focal or diffuse. There is a retraction artifact between
alveolar exudate and the alveolar septa in formalin-fixed tissue (Figure 2). This feature is also characteristic of
Pneumocystis jirovecii pneumonia.
Pulmonary alveolar proteinosis (PAP) and pulmonary
edema also cause a similar foamy exudate in the H & E
stained sections. In PAP, there are cholesterol clefts and
lipid-containing macrophages in alveolar spaces. In our
case, there was a typical honeycomb appearance of alveolar
exudate which is typical for P. jirovecii pneumonia. At
higher magnification, the microorganisms appear as tiny
basophilic dots within the spaces of the frothy exudate. In
GMS-stained sections, organisms appear as small (6-8 μm),
oval to round or crescent-shaped. The cyst walls are black
and characteristically there is a focal, darkly staining area of
P. jirovecii does not bud and this feature can be used to
distinguish between this organism and fungi, such as small
variants of Blastomyces dermatitidis, Candida glabrata,
capsule deficient Cryptococcus species and Histoplasma
There are commercially available antibodies to P. jirovecii
in routinely processed cytology and biopsy specimens.
They can identify both the cyst and the trophozoite forms
of P. jirovecii in clinical specimens 15.
There are also molecular techniques such as real-time PCR
for the detection of the organism. One should be careful
during the assessment of the real-time PCR results as P.
jirovecii is also found in healthy individuals. The clinical
and laboratory results should therefore be considered
together to decide whether treatment is necessary or not
P. jirovecii cannot be cultivated on cell-free media in the
clinical laboratory and the diagnosis of PCP depends
mainly on the demonstration of the organism in biopsy or
Hypoxia is the hallmark of the PCP, but the clinical findings
depend on the host immune status. Fever, nonproductive
cough, tachypnea, and severe dyspnea may be observed.
Cyanosis may be present or may develop rapidly. In acute
progressive infection with respiratory failure, diffuse alveolar
damage, hyaline membranes and reactive epithelial cell
proliferation may be seen. In chronic infection, interstitial
and intraluminal fibrosis may be seen 17.
Patients at high risk for PCP, specifically HIV-infected
patients with CD4+ T-lymphocyte counts of less than 200
cells/mm3 and all AIDS patients who have already had one
or more episodes of PCP receive prophylaxis with TMPSMX
and aerosolized pentamidine 18.
In conclusion, when physicians come across a diagnosis
of PCP, HIV infection should be investigated. PCP is a
relatively common AIDS-defining infection. As in our case,
diagnosis of disease through the pathological examination
of tissues (biopsy samples) or bodily fluids could lead to the
recognition of an unrevealed HIV infection.
CONFLICT of INTEREST
The authors declare no conflict of interest.
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