Role of Bone Marrow Examination in the Evaluation of Infections: Clinico-Hematological Analysis in a Tertiary Care Centre
Vijay KUMAR, Akanksha BHATIA , Garima Baweja MADAAN, Sadhna MARWAH, AS NIGAM
Department of Pathology, PGIMER, Dr. Ram Manohar Lohia Hospital, NEW DELHI, INDIA
Keywords: Bone marrow examination, Infections, Pyrexia, Tuberculosis, Visceral leishmaniasis, HIV
Bone marrow examination (BME) is an important modality for investigation of case of pyrexia of unknown origin (PUO). However,
its yield in the diagnosis of infections has not been extensively studied and its role has not been well established. The aim of the study was to
investigate the usefulness of BME and to evaluate the etiological and clinico-hematological profile in cases of bone marrow infections.
Material and Method: This was a retrospective study where bone marrow cases were retrieved and a review of bone marrow findings with an
infectious etiology from July 2014 to June 2018 was done. Detailed history, clinical examination and hematological parameters at presentation
were recorded. Clinico-hematological correlation using descriptive statistics was performed.
Results: The study included 55 cases, on analysis of which the maximum number of infections were those of leishmaniasis accounting for
35%, followed by HIV (29%) and tuberculosis (15%). Other etiological agents included fungal infections (histoplasmosis and aspergillosis),
Enteric fever, Scrub typhus, parvovirus, falciparum malaria and filariasis. The most common clinical presentation was fever (80%) and the most
common clinical finding was splenomegaly (66%).
Conclusion: Bone marrow examination is an important diagnostic tool to delineate etiological diagnosis in infectious conditions, particularly
those presenting with PUO. Moreover, it is particularly important if urgent diagnosis is required or if alternate diagnostic modalities have not
revealed a reason for PUO.
Bone marrow examination (BME) plays an important role
in diagnosis of hematological as well as non-hematological
disorders. It is a simple and safe procedure and is particularly
useful in the investigation of pyrexia of unknown origin as
it leads to an etiological diagnosis in most of the cases 1,2
. Anemia and other peripheral cytopenias are the most
frequent indications for bone marrow examination and
may be the presenting signs of a clinically unsuspected
infection identifiable within the bone marrow.
Bone marrow changes resulting from infections can
be studied by analysis of morphology and etiology. On
morphology, similar lesions can be seen to arise from
different infectious agents and one agent can give rise to
various lesions (3). Routine staining procedures (Giemsa)
may be very helpful in the diagnosis of viral inclusions,
some parasites (Leishmania, Toxoplasma, Microfilaria)
and fungi (Histoplasma, Cryptococcus). Sometimes special
stains like Ziehl-Neelsen (ZN) and periodic acid-Schiff (PAS) stains may be required to identify organisms like
Mycobacterium and certain fungi.
The yield of bone marrow examination in the diagnosis of
infections has not been extensively studied and its usefulness
has not been well established. Hence, a retrospective study
was performed to investigate the role of BME along with
clinico-hematological analysis; and to help clarify its role
in the diagnosis of various infections.
The study was a retrospective study conducted in the
Department of Pathology. All case records of bone marrow
examination were retrieved and the bone marrow findings
were reviewed from July 2014-June 2018; and those
diagnosed as infections were included in the study. Clinical
details, biochemical profile, complete hemogram with
peripheral smear, bone marrow aspiration smears and bone
marrow biopsy slides (wherever available) were reviewed
and data were analyzed. All cases where bone marrow
aspiration/biopsy was inadequate for an opinion were excluded from the study. Institutional ethical clearance was
not obtained as it was a retrospective study.
Peripheral blood smear was routinely examined along
with the bone marrow aspiration and biopsy slides and
cytopenia was defined as: hemoglobin < 10 gm/dL, total
leucocyte count <4×103/μL and platelet count<100×103/
μL. Bone marrow aspiration and trephine biopsy had been
carried out as per the clinical indication. The bone marrow
procedure was carried out by standard methods. All the
bone marrow aspirate smears and trephine biopsies were
stained with Giemsa and hematoxylin and eosin (H&E).
In addition, wherever indicated, PAS and ZN stains were
applied to aspirate smears and biopsies. Bone marrow
culture was not available in these cases. Statistical analysis
using descriptive statistics was done.
The study included 58 cases, out of which 3 samples were
hemodiluted and hence were excluded from the study. Of
the remaining 55 cases, bone marrow aspiration and biopsy
had been performed for 27 cases (49%); whereas only
aspiration had been done in 28 cases (51%). There were
42 (76%) cases of adults and 13 (24%) of children; and the
mean age of presentation was 32.3 years (range, 1-72 years).
The male:female ratio was 2.2:1. The clinical presentation
of the cases varied from high grade fever and abdominal
pain to non-specific symptoms like generalized weakness
). Fever was the commonest symptom and seen in
80% of the cases (n=44).
On clinical examination, splenomegaly was the commonest
finding, seen in 66% of the cases (n=36). Other significant
findings were hepatomegaly, lymphadenopathy, effusion
(ascitic/pleural/pericardial) and pallor (Table II). The HIV
antigen was found to be positive in 29% of the cases (n=16)
and the RK39 antigen for leishmaniasis was positive in 16%
of the cases (n=9).
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|Table II: Clinical examination and investigations of the cases
included in the study.
On peripheral smear examination, anemia was the most
common finding seen in 91% of the cases (n=50). The most
common type of anemia was the normocytic normochromic
type. Other findings were pancytopenia, leucopenia,
thrombocytopenia and rouleaux formation. Common
hematological findings are summarized in Table III.
On bone marrow examination, an increase in plasma
cells and histiocytes along with hemophagocytosis
was commonly observed. Erythroid hyperplasia and
dyserythropoiesis were also commonly seen (Table ttable4>IV). A
total of 19 cases showed presence of Leishmania donovani
(LD) bodies (Figure 1A,B). Granulomas were seen in 8 cases; however acid fast bacilli could be demonstrated
only in 1 case on ZN staining (Figure 2A-C). PAS positive
histoplasma was observed in 3 cases (Figure 1C,D). Giant
proerythroblasts having intranuclear inclusions (Figure
3B) suggestive of parvo virus infection; and gametocytes of
Plasmodium falciparum (Figure 3C) were seen in two cases each. There were one case from each of aspergillosis (Figure 2D) and microfilariasis (Figure 3D). Erythroblastopenia
and erythrophagocytosis were also observed. The spectrum
of infections observed in the study is demonstrated in
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|Figure 1: A,B) Visceral leishmaniasis: Bone marrow aspirate showing presence of intracellular (A, blue arrow) and extracellular (B,
red arrow) LD bodies (Giemsa; x1000). C,D) Histoplasmosis: Bone marrow aspirate showing presence of intracellular (C, green arrow;
Giemsa; x1000) and extracellular (D, yellow arrow; PAS; x1000) histoplasma.
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|Figure 2: A-C) Tuberculosis: Epithelioid cell granulomas on bone marrow biopsy seen in a case of HIV (A,B; H&E; x400) and acid fast
bacilli seen on ZN stain (C; ZN; x1000). D) Aspergillosis: Bone marrow biopsy showing presence of numerous acute angle branching
hyphae of Aspergillus (H&E; x1000).
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|Figure 3: A) Bone marrow aspirate showing presence of hemophagocytosis in a case of Scrub typhus (Giemsa; x1000). B) Giant
proerythroblast with nuclear inclusion and erythroblastopenia seen in a case of Parvovirus infection (Giemsa; x1000). C) Gametocytes
of Plasmodium falciparum seen on bone marrow aspirate seen in a case of Malaria (arrow; Giemsa; x1000). D) Bone marrow aspirate
showing Microfilaria (Giemsa; x200).
A variety of morphologic changes in the bone marrow have
been described in various infectious. These changes may be
features of acute inflammation (interstitial edema, vascular
congestion, hemorrhage, ischemic necrosis or suppurative
necrosis) or chronic inflammation with granuloma
formation, reactive lymphoid hyperplasia, plasmacytosis,
histiocytosis or fibrosis 3
. Bone marrow examination can
also lend to the etiological diagnosis in many cases.
Many studies have demonstrated the utility of bone marrow
in a particular type of infection; however no study has been
done which has studied the spectrum of infections which
can be seen on bone marrow examination 4,5.
In this study, there were 19 cases (35%) where amastigote
forms of LD bodies were seen. Of these, there was one case
of HIV infection which developed visceral leishmaniasis, and showed presence of granulomas with LD bodies even
on FNAC of cervical lymph node. In the bone marrow
aspirates, LD bodies were mostly seen both intracellularly
and extracellularly (89.5%). Corresponding bone marrow
biopsy was available in 8 of these cases, of which LD bodies
were seen in 6 cases (75%). Other findings associated with
leishmaniasis were reactive plasmacytosis in the bone
marrow seen in 79% of the cases and rouleaux formation
on peripheral smear seen in 2 cases. Clinically, fever
was the most common presenting symptom (95%) and
splenomegaly was seen in all cases. This is in accordance with
various studies and case reports of visceral leishmaniasis 6.
In a study conducted by Chandra et al. similar findings have
been observed. In their study, fever was the most common
presenting feature followed by hepatosplenomegaly 7.
Plasmacytosis and hemophagocytosis were common
findings and were attributed to the longer duration of the
There were 16 cases (29%) of diagnosed HIV infection for
which bone marrow examination was done. Out of these,
opportunistic infections like tuberculosis was seen in one
case (granulomas with positive ZN stain) and presence
of LD bodies in another. Two cases showed presence of
malignancy (T-cell lymphoma and acute leukemia). One
case showed therapy related changes in the bone marrow
and one case was hypocellular with focal gelatinous changes.
The rest of the HIV positive cases showed reactive changes
like reactive plasmacytosis and prominence of histiocytes.
Dyshemopoiesis in the form of dyserythropoiesis was
seen in most of the cases. However, the diagnostic yield of
bone marrow in HIV infections in the present study was
only 31%. This is similar to study conducted by Pande et
al. where the diagnostic yield of bone marrow was 26%
9. However, in the present study there were only 2 cases
(13%) of superadded infections being diagnosed on bone
marrow and fungal infections were not identified. This is in
contrast to the above-mentioned study, where superadded infections accounted for 50% of the cases. However, there
were two cases of malignancy (T-cell lymphoma and acute
leukemia) which also accounted for 13% of the total HIV
cases. Other non-specific findings like dysplastic changes
and plasmacytosis have been reported in various other
studies as well 9,10.
There were 8 cases (15%) of tuberculosis in our study,
including the one seen in a HIV positive patient. Of these 8
cases, 5 of them showed granulomas only in bone marrow
biopsy; one case showed granulomas both in aspirate and
biopsy; and 2 cases showed granuloma only in the marrow
aspirate. However, ZN stain was positive only in one case.
This may be due to the fact that acid fast bacilli are seen
only in 25% of marrow biopsies as claimed by other studies
11. So, in a country like India it is difficult to rule out
tuberculosis in the absence of any associated findings with
the granuloma. Cases with caseous necrosis were also seen
in 3 cases (38%). This is similar to findings observed by
Gupta et al. 6.
Fungal infections accounted for 4 cases (7%) of which 3
were that of histoplasmosis. Of these 3 cases, 2 presented
with fever and one with pancytopenia. PAS positive
Histoplasma organisms were seen mainly intracellularly
in two cases and both intra- and extracellularly in one
case. In a study conducted by Chandra et al., similar
findings were observed in a case of histoplasmosis on
bone marrow aspirate; however they have also described
hemophagocytosis as a clue towards diagnosing the disease
12. In the present study, however, hemophagocytosis
was not observed in any of the cases. There was one case
of aspergillosis where PAS positive acute angled fungal
hyphae were seen in the bone marrow biopsy. Serology
for HIV was negative in all of the four cases. This is unlike
other studies wherein fungal infections in the marrow have
been mostly described in HIV positive cases 13.
Other than these above mentioned infections, there were
3 cases of enteric fever where erythrophagocytosis was
evident in the marrow. However, no granulomas were
seen. Two of these cases turned out to be WIDAL positive
and one case was Typhidot positive. This is in accordance
with many studies where presence of erythrophagocytosis
without granuloma was seen in cases of enteric fever 14.
There were 2 cases of scrub typhus which showed evidence
of hemophagocytosis with mild dyserythropoiesis.
Two cases of parvo virus infection (parvo IgM positive)
were also included in the study, and showed paucity of
erythroid precursors with giant proerythroblasts having
intranuclear inclusions on bone marrow aspirate. These findings were similar to those described in earlier studies
15. However, B19 DNA PCR was not done in the present
case. Two cases of falciparum malaria were also observed;
wherein gametocytes of Plasmodium falciparum and
intracellular hemozoin pigment within the histiocytes were
observed. There was also a case of filariasis that presented
with fever and where microfilaria were identified on bone
As the bone marrow aspiration and biopsy was performed
by the clinical departments, bone marrow biopsy had not
been done in 28 of the cases. This could partly be due to
technical reasons. Nevertheless, bone marrow aspirates
were adequate in those cases and a diagnosis could be
In conclusion, bone marrow aspiration and biopsy can
be useful in diagnosing a variety of infections including
bacterial, fungal, parasitic and even viral, in conjunction
with the clinical findings. This study assumes more
significance particularly in those cases where bone marrow
culture is not available or remains non-contributory.
Bone marrow examination is an important diagnostic tool
to delineate etiological diagnosis in infectious conditions,
particularly those presenting with PUO. Moreover, it is
particularly important if urgent diagnosis is required or if
alternate diagnostic modalities have not revealed a reason
for PUO. This study highlights the role of bone marrow
examination as an important diagnostic modality for the
etiological diagnosis of infection and thereby, helps to
provide better management of such cases. To the best of our
knowledge, no similar comprehensive study elucidating
the role of bone marrow examination in the diagnosis of
infections has been found in the literature.
CONFLICT of INTEREST
The authors declare no conflict of interest.
The authors received no specific funding for this work.
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