Biomedical Engineering Reference
In-Depth Information
Hemangiomas
Vascular tumors are the second main group of vascular lesions
that can be treated with lasers. Within this group are infantile
hemangiomas (IHs), unique tumors that arise only in infancy
and that represent the focus of one of the major controversies
in laser surgery today. The relative lack of well-designed, pro-
spective, randomized controlled trials, the use of variable laser
devices and specifi c treatment parameters, and the natural
history of the lesions themselves complicate the evidence-
based evaluation of laser surgery as a treatment modality for
IH—uncomplicated or otherwise.
IHs constitute the most common vascular tumors of early
infancy and remain a frequent reason for referral to a special-
ist. The estimated incidence of IHs ranges from 1% to 2.6% in
healthy infants in the immediate newborn period to about
4-10% of infants by 1 year of age. A female predominance has
been described ranging from 2:1 to 9:1 (135), with Caucasian
infants having a higher reported incidence over other racial
groups; whether this refl ects some underlying aspect of the
pathophysiology of IH or simply a reporting bias remains to
be elucidated. Advanced maternal age, chorionic villus sam-
pling (vs amniocentesis), prematurity, low birth weight (less
than 1500 g), multiple gestation, and history of placental
abnormality suffered by the mother either during gestation or
delivery have all been reported as statistically signifi cant risk
factors for IH (136,137).
Histopathologically, these lesions are composed of benign
proliferations of plump endothelial cells with a unique vascu-
lar phenotype. Glutaminase transferase 1 staining of these
lesions is positive and demonstrates small, scanty capillaries,
a feature that persists throughout the natural progression of
IH and can help confi rm the diagnosis (138). Current theories
on the pathogenesis of these lesions suggest that IHs are struc-
turally similar to human placental blood vessels and may in
part be a disorder infl uenced by the combination of vasculo-
genesis (i.e., de novo formation of blood vessels from circulat-
ing stem cells) and angiogenesis (i.e., the sprouting of vessels
from existing ones) (139).
IHs have a stereotypical natural history of rapid growth
early in infancy followed by involution. Although most IHs
are not evident at birth, the astute clinician may observe a
localized area of pallor, macular erythema, or telangiectasia
that may serve as a premonitory mark that helps delineate the
future territory of the lesion, which typically appears within
the fi rst few weeks of life. Serial physical examinations may, at
this point, be necessary to distinguish IH from a capillary
malformation. Notably, IH lesions will characteristically
progress and undergo rapid proliferation in which the major-
ity of growth is completed by about six to nine months of age,
with deep hemangiomas tending to appear later and remain-
ing in the growth phase longer than their superfi cial counter-
parts. IHs tend to characteristically maintain their shape and
anatomic distribution during this proliferative phase sug-
gesting, as Chang et al. have worded it, that hemangiomas
“mark out their territory” early in life (140). Involution, char-
acterized clinically by increased ballotability and change from
crimson to dull grayish-purple on the surface, occurs during
the fi rst several years of life. New understandings of the
molecular basis of IH pathogenesis suggest that this fi nal
phase is less “spontaneous” than previously thought, most
likely representing a dynamic process in which forces favor-
ing apoptosis prevail over those propagating proliferation.
Studies of the natural history of IHs reveal that complete
resolution occurs in 50% of children by age fi ve years and 70%
by age 7 years, with continued improvement in the remaining
children until 10-12 years of age (141,142). For this reason
alone aggressive therapy for uncomplicated IH is generally not
warranted. A minority of lesions will not completely involute,
however, and those lesions that do not show signifi cant signs
of regression by age 6 to 8 years are less likely to completely
regress (142,143). Importantly, regression does not necessarily
imply totally normal skin, and postinvolution changes may
leave behind a cosmetically unacceptable result. Hemangioma
residua may include telangiectasia, atrophic or redundant
skin, scarring, and underlying fi brofatty tissue. In certain cos-
metically sensitive anatomical locations, especially the face,
treatment may be preferred in order to minimize physical and
psychosocial sequelae.
The clinical presentation and signifi cance of IH varies
greatly and is often linked to the location, size, and type.
Descriptive terms such as “strawberry,” “cavernous,” and “cap-
illary” are considered antiquated and should no longer be used
in conjunction with IH. Instead, IHs tend to be classifi ed based
on the depth of tissue involvement (superfi cial, deep, and
mixed) and/or divided by whether they are localized (i.e., spa-
tially confi ned) or segmental (i.e., territorial in distribution)
(144). Superfi cial hemangiomas are the most common type,
accounting for approximately 50% of cases. Combined hem-
angiomas are estimated to occur in 25-35% of cases, and deep
hemangiomas in about 15%.
IH can present anywhere on the body. They most commonly
involve the head and neck regions, with the majority of facial
lesions occurring on the central face in an apparent nonran-
dom distribution that may refl ect sites of development fusion
(145). Although most IHs are uncomplicated, a signifi cant
minority may involve a higher probability of complications
or may even suggest the possibility of associated fi ndings
(146,147). Segmental hemangiomas, especially on the face,
should raise concern for possible PHACES syndrome, which
refers to a constellation of clinical fi ndings that may include
posterior fossa brain malformations, hemangiomas, arterial
anomalies, coarctation of the aorta and cardiac defects, and eye
abnormalities (e.g., microphthalmia, optic nerve hypoplasia,
cataracts, coloboma, and increased retinal vascularity), sternal
clefting, and supraumbilical abdominal raphe (148). Periocu-
lar and orbital hemangiomas pose a risk for visual axis obstruc-
tion, with the development of amblyopia or retrobulbar
involvement primary concerns (149). IH blocking the ear canal
may interfere with auditory function. IH lesions located in a
“beard distribution,” (overlying the lower lip, mandible, chin,
and neck) are at risk for concomitant upper airway or subglot-
tic involvement and may present with an increasing degree of
noisy breathing, stridor, hoarse cry, or other signs of airway
obstruction. Nasal tip hemangiomas are known to distort the
nasal anatomy and may result in the “Cyrano” nasal deformity.
Head, neck, genital, and perineal lesions located in areas of
increased friction are at a higher risk for erosion, ulceration,
and pain. Lesions located in the lumbosacral area may them-
selves be a marker for spinal dysraphism or may be associated
with perineal hemangiomas, external genital malformations,
