Discussion
KHE is a rare vascular neoplasm during infancy and should be carefully
differentiated from infantile hemangioma1. The
prevalence of KHE in Massachusetts is about 1 in 100,000
children2. It can present as a raised subcutaneous
mass, involving the extremities, trunk, or cervicofacial region. In
addition, it may present as intrathoracic or retroperitoneal lesions in
10% of patients, not involving the skin2. The major
pathological manifestations of KHE are abnormal angiogenesis and
lymphangiogenesis3. Diagnosis is based on the
combination of clinical, histologic, and imaging features. MRI can
illustrate an ill-defined mass, hypointense or isointense compared with
muscle in T1-weighted sequences, and hyperintense in T2-weighted
sequences4. Although KHE is a benign vascular tumor
that does not spread to other parts of the body, it can grow
aggressively and is often associated with the most serious complication,
KMP, which is a life-threatening complication of KHE. The KMP was first
described in 1940 with characteristics of active consumptive
coagulopathy5. Therefore, laboratory data can show
profound thrombocytopenia and hypofibrinogenemia with elevated markers
of coagulation activation. In a large cohort study2,
the risk factors for KMP included the tumor location (intrathoracic or
retroperitoneal involvement), the tumor depth (infiltration into muscle
or fascia), and the tumor size (maximum diameter greater than 8 cm).
Immediate management is needed to avoid high mortality and morbidity. It
is currently thought that KMP occur in approximately 70% of KHE, but
not in infantile hemangioma4,6. Given the high
mortality range from 8 to 24%4,7, accurate diagnosis
and prompt treatment are important. However, there is no standard
treatment guideline due to the rarity of KHE.
The treatment method for KHE is mainly based on the opinions of experts,
and a small number of case reports and case series. Supportive treatment
should be provided first to prevent the patient’s condition from getting
worse, followed by curative therapy for the underlying vascular tumor.
Fresh frozen plasma or cryoprecipitate is used to correct coagulopathy.
Platelets are reserved for active bleeding or before surgery, because it
will exacerbate mass bleeding and platelet trapping in the
tumor3,8. Although surgical resection is considered to
be the standard method for the treatment of vascular tumors, it is
difficult to perform during the active phase of KMP due to acute
bleeding and severe coagulopathy. Since most KHE is infiltrative and may
invade adjacent organs, it is almost impossible to obtain a clear tumor
margin for surgery9. Arterial embolization may be an
effective treatment method for KHE combined with KMP, but its main
limitation is the technical difficulty of accessing the very small
feeding arteries in neonates and young infants3.
Previous studies have found that arterial embolization only had a
temporary therapeutic effect for some cases of KMP7.
According to the 2013 consensus of medical treatment for complicated
KHE9, intravenous vincristine 0.05 mg/kg once a week
and oral prednisolone 2 mg/kg/day or intravenous methylprednisolone 1.6
mg/kg/day are recommended as the first-line treatment for KHE patients
with KMP, and oral prednisolone 2 mg/kg/day is recommended for those
without KMP. Sirolimus has recently been suggested as an alternative
therapy for KHE 3,8. Cashell J, et al. reported the
life-saving treatment of an infant with KHE and KMP after three weeks of
treatment with prednisolone, vincristine, and
sirolimus10.
In the acute stage of KMP, it is difficult to perform surgery when there
is evidence of bleeding tendency. On the other hand, drugs take too long
to correct coagulopathy with active bleeding. Transcatheter arterial
embolization may be an alternative therapy. However, to the best of our
knowledge, there are no case reports of such small infants receiving
arterial embolization to treat KHE. In the present case, a 9-day-old
newborn underwent arterial embolization for KHE with KMP, combined with
sirolimus treatment, and the outcome was favorable. Our successful
experience of treating KHE with KMP revealed that transcatheter arterial
embolization is feasible and can be used as an alternative to surgical
resection, even in small babies.