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Diseases of the blood involving
infants, children, and adolescents are commonly encountered by primary
care physicians. Many hematologic problems are straightforward and, therefore,
easy to diagnose and manage without involvement of a subspecialty
consultant. Yet others are rare, serious, or even life threatening, representing
complex diagnostic and management challenges. In such cases, engagement
of a pediatric hematology-oncology subspecialist is recommended.
The American Board of Pediatrics has certified more than 2000 practitioners in
this subspecialty.
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For good reason, hematology and oncology have been combined as
a single subspecialty discipline for several decades.1,2 One
of the first recognizable conditions treated by children’s
blood specialists was acute leukemia. As the principles of combination
chemotherapy became clear during the 1960s, the drugs used to treat leukemia
were also found to be effective in treating solid malignant tumors.
Accordingly, it was (and still is) the hematology specialist who
becomes skilled in these agents’ use in the care of leukemia and
other cancer patients. Hematology-oncology thus became a combined
specialty by the 1970s and has remained so from the standpoint of
board certification. Nevertheless, the increasing complexity of
the field during the past few decades has resulted in some practitioners
focusing primarily in one clinical area (oncology) or the other (hematology),
especially those working in large metropolitan areas where patient
numbers justify this subsubspecialization. Hematology-oncology specialists
tend to be concentrated in academic medical centers where they conduct
clinical or laboratory research as well as teach and provide patient
care. For years, the standard of care in childhood cancer has included
these patients’ enrollment, if possible, in peer-reviewed
multicenter research studies. More recent advances have also fostered
clinical trial participation becoming accepted practice in children
with nonmalignant hematologic conditions such as sickle cell disease
and hemophilia.
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Most hematologic disorders encountered by pediatricians are mild,
transient, and/or secondary to another acute or chronic
illness. They are usually identified because of abnormalities in the
blood count rather than by signs or symptoms specific to the hematologic
condition. Nevertheless, some hematologic conditions are chronic,
severe, and often familial in nature. Expertise in hematologic disorders
during childhood thus requires a keen interest in and knowledge
of genetics.
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Many diseases during childhood involve a specific organ, such
as the heart, lungs, kidneys, or brain. Strictly speaking, the blood
is not an organ but a liquid tissue that circulates throughout the
body; thus, an abnormality can have diverse clinical consequences
affecting many organs. The primary organ of the blood is the bone
marrow cavity, where postnatally the majority of blood cells are
produced. Other hematologic organs include the spleen and lymph
nodes, which contain diverse antibody-producing cells and lymphocytes.
The spleen is also a rich source of macrophages that remove senescent blood
cells, bacteria, and other soluble and particulate matter from the
bloodstream.
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Children with blood diseases may present with signs and/or
symptoms thereof, but more commonly exhibit manifestations that
are nonspecific or secondary to ...