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.