Discussion
Fetal eye deformities are rare, including anophthalmia, microphthalmia,
cataract, and PHPV, and clinical reports mainly focus on fetal
cataracts. Eye diseases are more common in term children and men, and
about 90% of patients have unilateral diseases4.
However, bilateral onsets are mostly accompanied by other ocular and
systemic abnormalities, including congenital trisomy 13, Walker–Warburg
syndrome, or Norrie disease, which are clinically described during the
postpartum period according to related manifestations. PHPV is often
manifested as a “white pupil,” accompanied by cataracts, glaucoma,
vision loss, and lens opacity. In severe cases, intravitreal hemorrhage,
congenital retinal detachment, and even eyeball atrophy may
occur5.
Normally, the primitive vitreous develops from the intercellular space
between the lens vesicle and primitive optic vesicle at 6–12 weeks of
the pregnancy. During the same period, the blood vessels in the
primitive vitreous begin to shrink gradually, and the primitive vitreous
is completely degenerated and absorbed after delivery. If the primitive
vitreous body is not completely degenerated and absorbed during
embryonic development, and the fibrovascular connective tissue is
abnormally proliferated, it will form a persistent primitive vitreous
hyperplasia.
Prenatal two-dimensional ultrasonography showed that the central part of
the vitreous was hyperechoic with a “funnel” or “inverted triangle”
shape6. The posterior wall of the lens was connected
to the base, and the tip was connected to the optic disk. One side of
the orbit is smaller than the other side. A three-dimensional surface
imaging showed hyperechoic fibrous plaques in the vitreous inside the
eyeball, and color Doppler blood flow detected blood flow signals in
strip arteries7.
PHPV has a poor prognosis, and if left untreated, it can cause repeated
intraocular hemorrhage and secondary glaucoma, which may, eventually,
require enucleation. However, the disease should be differentiated from
Walker–Warburg syndrome and congenital cataract6.
Congenital cataracts have a good prognosis and can be treated after
birth. On ultrasound, cataracts are mainly detected in the lens, mostly
in both eyes, with typical oval ring echoes. Walker–Warburg syndrome is
an autosomal recessive syndrome. Its main features are congenital
muscular dystrophy, hydrocephalus, cerebellar vermis hypoplasia,
cerebellar hemisphere hypoplasia or corpus callosum hypoplasia,
encephalocele, and ophthalmia with microscopic ocular malformations,
including persistent primary vitreous hyperplasia. Norrie disease is
another X-linked recessive disease that causes bilateral PHPV, and its
features include early childhood leukocytosis, deafness, mental
retardation, and loss of retinal ganglion cells. Glaucoma and cataracts
can coexist. The phenotypic features include growth restriction, narrow
nasal bridge, large ears, hypogonadism, and undescended testes. Since no
other systemic abnormalities were present in our patient, she was
diagnosed with isolated persistent vitreous hyperplasia.
Retinoblastoma, the most common malignant intraocular neoplasm of
childhood is the most common cause of leukocoria which is a cose mimic
of PHPV3,8. There have been very rare reports
detailing in utero imaging of retinoblastoma. However, retinoblastoma is
often associated with normal globe size and a calcified mass. PHPV is
the second most common cause of leukocoria after retinoblastoma.
Prenatal ultrasound reveals reduced eyeball and shows an echogenic band
extending from the posterior surface of the lens capsule to the optic
disc without any evidence of calcification.
In conclusion, PHPV with Rb is an important disease that can be
diagnosed prenatally. This case illustrates the value of prenatal
screening for persistent hyperplastic primary vitreous with
retinoblastoma. However, it should be noted that the eyes may appear
normal in the second trimester and abnormal in the third trimester.
Additionally, for intrauterine diagnosis in subsequent pregnancies, it
is recommended that prenatal genetic testing be performed at an early
stage.