Purpura, Petechiae, Meningococcemia, HSP, Osler-Webber-Rendu
Vascular disorders may be responsible
for petechiae
or purpura
in children who have normal or increased platelet counts.
Meningococcemia and other bacterial
infections are critical causes of vascular
purpura
because of the high associated morbidity and mortality and the critical need to
consider the diagnosis and begin therapy rapidly. The purpura is due to
either direct vascular invasion by the organism or to an endotoxin-induced
Schwartzman reaction. Clinically,
erythematous
papules are seen initially, but they soon evolve into widespread
petechiae
with purple to slate-gray purpura.
Disseminated intravascular coagulation (DIC)
develops less frequently, causing
petechiae
and purpura
due to both thrombocytopenia and
acrocyanosis that
progresses to symmetric peripheral gangrene following fibrin deposition.
Patients who have DIC are very ill-appearing and in septic shock. Laboratory
studies reveal thrombocytopenia, hypofibrinogenemia, and prolongation of the
partial thromboplastin time and the prothrombin time.
Other
infectious etiologies of vascular
purpura
include gram-negative sepsis
(particularly in association with granulocytopenia or immune suppression),
scarlet fever,
Haemophilus
influenzae
infection, Streptococcus
pneumoniae infection, Rocky
Mountain spotted fever, and disseminated fungal infections.
Viral
infections are the most common causes of vascular
purpura.
Although the purpura occasionally can be due to specific viruses, such as
parvovirus B19 or Hanta virus causing hemorrhagic fever, most often it
occurs in otherwise well children who have a variety of more routine viral
illnesses. The critical clinical issue is to exclude the more serious bacterial
infections from the differential diagnosis before assuming a viral etiology.
Purpura
can be seen in a variety of other illnesses, including
glucocorticoid
excess, Ehlers-Danlos
syndrome, and serum sickness.
Henoch-Schönlein
purpura
is the most common cause of noninfectious vascular
purpura
in children. The palpable purpuric lesions are distributed
classically on the lower extremities, avoiding the trunk and head.
Collagen-vascular disorders also may present with a
purpuric
rash. The classic "blueberry
muffin" baby has a vasculitis that most often is due to congenital
toxoplasmosis, rubella, or cytomegalovirus.
Hereditary hemorrhagic
telangiectasia
(Osler-Weber-Rendu
syndrome) is an autosomal dominant disorder that usually presents with
recurrent epistaxis that worsens with age.
The most severely affected patients develop epistaxis during childhood, with
cutaneous changes beginning to appear at puberty.
The lesions of vascular purpura are usually palpable. In
contrast, the petechiae and purpura of platelet dysfunction typically are
nonpalpable. Platelet
dysfunctions must be considered in patients who have
purpura
and normal platelet counts. Clinically significant platelet dysfunctions
in children usually are due to a variety of congenital disorders. The clinical
history and physical examination generally will allow differentiation of
platelet dysfunction and vascular purpura, with the latter usually associated
with a more specific rash. Platelet function studies occasionally may be
necessary to document a platelet disorder.
References:
Baselga E, Drolet BA, Esterly NB. Purpura in infants and children. J
Am Acad Dermatol. 1997;37:673-705
Schneiderman P. The vascular purpuras. In: Beutler E, Lichtman MA,
Coller BS, Kipps TJ, eds. Williams Hematology. 5th ed. New York, NY:
McGraw-Hill; 1995:1401-1412