2015, Volume 31, Number 2, Page(s) 158-160
Parvovirus B19 Induced Transient Aplastic Crisis in an Immunocompetent Child
Meetu AGRAWAL1, Roshni Tara PAUL1, Promod PAMU1, Narendra AVMR2
1Nizam's Institute of Medical Sciences, Department of Pathology, HYDERABAD, INDIA
2Nizam's Institute of Medical Sciences, Department of General Medicine, HYDERABAD, INDIA
Viral-induced aplastic crisis is an important cause of
unexplained anaemia. It becomes significant in the context
of an immunocompromised host. However, it is commonly
overlooked in a well-nourished immunocompetent
host. Parvovirus B19-induced transient crisis is one such
example. Bone marrow study is a commonly performed
preliminary investigation for an unexplained anaemia and
can provide important morphological clues as in our case.
We encountered classic Parvovirus B19 inclusions in the
proerythroblasts of the marrow while looking for the cause
of severe anaemia in an immunocompetent child.
Our patient, an 11-year-old girl, was apparently
asymptomatic 15 days before presentation and then
developed high grade fever which subsided after 4 days.
She started to complain of unrelenting fatigue and her
parents noticed progressive pallor. She was evaluated on
an out-patient basis, wherein the only positive finding
was severe pallor. There was no rash, organomegaly or lymphadenopathy. She was moderately built. Complete
blood picture revealed a haemoglobin of 5.6gm/dl, total
leucocyte count of 2800/mm3 with normal differential, and
platelet count of 2.8x105/mm3. Her biochemical evaluation
revealed serum iron of 95 μg/ml, folate level: 11 ng/ml.
B12: 547 pg/ml, bilirubin: 0.7 mg/dl and SGPT/SGOT: 33/
28 U/l. In view of bi-cytopenia with normal biochemical
parameters, she underwent a bone marrow study. The
marrow aspirate smears were particulate with increased
cellularity. There was myeloid prominence (M: E= 7:1) with
normal and orderly maturation. Severe erythroid hypoplasia
was noted with the only recognisable erythroid cell being
giant proerythroblasts (Figure 1A-D). These cells had large
megaloblastoid nucleus with 2-3 intranuclear nucleoli like
viral inclusions. The cytoplasm was moderate in amount and
basophilic with irregular fuzzy margins, classically described
as “dog ears”. Megakaryocytes were mostly unremarkable
except for occasional presence of emperipolesis (Figure
1E). Bone marrow biopsy showed similar features (Figure
1F). Extensive work up for any underlying causes of hypoproliferative or hemolytic conditions and immunedeficiency
was negative. Correlating the presence of red
cell hypoplasia with characteristic intranuclear inclusions,
a diagnosis of ‘transient aplastic crisis probably due to
Parvovirus B19' was made.
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|Figure 1: Low power photomicrographs of A) Peripheral smear showing mild anisocytosis and leucopenia (MGG; x100). B) Marrow
aspirate with marked myeloid prominence (MGG; x100). C) Abnormally large proerythroblasts with classic intranuclear viral inclusions
(x200) and D) High power photomicrograph of proerythroblast with inclusions, cytoplasmic vacuolation and fuzzy “ dog ear” like
outpouchings (x400). E) Megakaryocyte showing emperipolesis (x200). F) Giant erythroid precursors on biopsy (H&E; x200).
Serological tests were not done. In view of the severe
anaemia, two units of packed red cells were transfused. The
patient recovered within 2 weeks of initial presentation and
is asymptomatic and healthy at present.
Both viral and bacterial agents may cause transient myelosuppression.
Bacteria-induced bone marrow hypoplasia
usually occurs in the setting of chemotherapy due to the
concurrent neutropenia. Viruses can affect various cell
lineages in the bone marrow. Dengue virus and Parvovirus
B19 directly affect megakaryopoiesis and erythropoiesis
respectively1. Direct viral targeting of the marrow cells
is the basic pathogenetic mechanism in these cases. Human
herpes virus 6 (HHV-6) and disseminated adenovirus
infections have also been reported to cause marrow
suppression in immunocompromised patients and mainly
transplant recipients2,3. In vitro cell culture studies
have implicated the Hepatitis A and non A, non B (NANB)
hepatitis viruses as causative agents of myelosuppression4,5. Amongst all of these, morphological changes have
been best described for Parvovirus B19.
Parvovirus B19 is a small DNA virus belonging to the
Picornavirinae family. Though overt infection manifests in
immunocompromised patients, most immunocompetent
individuals are also seropositive by 15 years of age6.
It is known to cause transient aplastic crisis in patients
with chronic underlying hemolytic disorders. However,
demonstration of its transient presence in the absence of
hemolysis or immunodeficiency is rarely reported.
The B19 virus is known to be associated with aplastic
crisis, erythema infectiosum or fifth disease, fetal
hydrops and arthropathy7,8. In humans, the cellular
receptor for the virus is the P antigen, located on mature
erythrocytes, platelets and tissues from the heart, lung
and liver. Within erythroid series, there is preponderance
for proerythroblasts. Individuals lacking in P antigen are
resistant to B19 infection.
The severity of the infection depends on the infected
person's age, and haematological and immunological
status8,9. Haematological disorders related to decreased
RBC production or increased destruction predispose to
Parvovirus-related transient aplastic crisis. However, a
complete workup for all these conditions was negative in
The viral inclusions in giant proerythroblasts are quite
characteristic and were seen in our case. A major drawback
of the present case is the lack of serological and PCR
correlation. One reason could be the almost complete
recovery of the patient and thus loss to follow up, even
before appropriate serology could be performed. This it is
a common problem in a developing country like ours. It is
therefore important to collect the relevant samples at the
initial visit and preserve aliquots.
We conclude that viral-induced hypoplastic crisis must
be kept in mind even in an immunocompetent host and
appropriate serological tests must be done if necessary.
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