Fig. 7: MRI scan at 2 months.
Brain tumors in the first year of life are predominantly supratentorial in location1-3. Congenital brain tumors, as defined by Arnstein et al, are those tumors that produce symptoms before 2 months of age4. Teratomas are the most common congenital intracranial neoplasm5-6. Congenital craniopharyngiomas are seen much less frequently, and there are few documented cases of these tumors7-10. Only one previous in-utero detection of a craniopharyngioma has been reported11. In a large study of midline supratentorial neoplasms from the University of Sao Paulo, of 1632 cases of intracranial neoplasms, 592 cases (36.2%) occurred in patients between 0 to 20 years. Of these, 3.5% were craniopharyngiomas, 1.35% hypophyseal neoplasms, and 6% pineal neoplasms28. The prevalence of these tumors in the fetus in unknown. Only 30% of craniopharyngiomas occur in children less than 16 years old24.
Etiology and pathogenesis
The origin of craniopharyngiomas is somewhat controversial. The term “craniopharyngiomas” is attributed to Cushing, who believed the tumor arose from cell rests derived from the craniopharyngeal duct12. Erdheim hypothesized that these tumors arose from remnants of Rathke"s cleft, and recent reports have supported this theory13-12.
Craniopharyngiomas are histologically benign tumors composed of bands of stratified squamous epithelium separated by connective tissue14 or an adamantinous or a squamous papillary structure. In a series of over 100 craniopharyngiomas the following histopathology types were found. “The frequently solid (50%), always uncalcified squamous papillary tumor type was found in one third of the adult patients (greater than or equal to 20 years) but did not occur in children. It was associated with a good functional postoperative outcome (84.6%). There have been no cases of tumor recurrence in the squamous papillary group. However, in the group with the adamantinous type of craniopharyngioma, the recurrence rate was 13% in adult patients and 9% in children. When compared to the adult adamantinous cases, the incidence of visual deficits was lower in the squamous papillary group (75% vs. 84%) but the incidence of endocrine abnormalities was higher (75% vs. 52%). Thus, the preoperative, operative, and postoperative features of the two types of craniopharyngioma were found to be distinctly different in adults and children”27. They are usually suprasellar in location, but some infrasellar cases have been reported15. Because of their location, these tumors may compress the optic chiasm and optic tracts or produce hypothalamic or pituitary dysfunction16 and hydrocephalus (from obstruction of the third ventricular cerebrospinal fluid outflow).
Signs and symptoms commonly produced by these tumors in older children include: headache, vomiting, visual loss and papilledema, endocrine disorders including short stature, obesity, hypogonadism, and diabetes insipidus17.
This case is the second documented case of in utero detection of a craniopharyngioma. The prenatal sonographic findings in both cases include a large, echogenic midline intracranial mass with suspected calcification. Hydrocephalus was absent in both case11. Polyhydramnios was reported in the previous case but was not seen in this case. Polyhydramnios and hydrocephalus have been variable findings in other cases of prenatally diagnosed intracranial masses2,5.
The CT appearance is that of a heterogenous suprasellar mass, often with non-uniform enhancement, and calcification is seen in 80% of cases18. The large size of these neonatal tumors is also a consistent finding7. Low-density cystic areas are reported in approximately 85% of cases, and these are frequently multilocular.
The MRI findings have been extensively reported, primarily in older patients. On T1-weighted images the signal characteristics are variable, depending on the amount of cholesterol, keratin, and methemoglobin in the tumor, and range from CSF to fat-like intensity19. On T2-weighted images, the masses are typically heterogeneous with high signal intensity. MRI, with the advantages of multiplanar imaging and high resolution, is the method of choice for evaluating the extent of these tumors and the degree of vascular encasement20.
There have been no anomalies consistently reported in association with congenital craniopharyngiomas. In two cases low-set ears have been noted; polydactyly, hypoplastic lung11, centronuclear (myotubular) myopathy25, or Moya-moya disease26 have also been reported. There is a mild female predilection among the reported cases, with boy to girl ratio of 4:7.
The primary differential diagnostic consideration of neonatal craniopharyngioma is a teratoma. This tumor occurs with greater frequency, is often suprasellar, large and contains calcification. The differential diagnosis between craniopharyngioma and teratoma in neonates is difficult radiologically, and biopsy is generally required to establish the diagnosis. Other neonatal intracranial neoplasms include astrocytomas, which may be suprasellar in location and in homogeneous in echotexture1 and optic chiasm and hypothalamic glioma. Primitive neuroectodermal tumors and lipoma of the corpus callosum should also be considered.
Although these tumors are benign histologically, and can be cured if completely removed, the prognosis for neonatal craniopharyngioma is very poor. Only one of 10 previously reported cases survived beyond one year of age7. The usual massive size and critical location of these tumors makes complete surgically removal very difficult21 and accounts for this poor prognosis. Complete removal provides the best prognosis but cannot always be achieved. When partial removal is performed it is usually supplemented by radiation therapy in older pediatric patients22. In lesions discovered during childhood and treated by surgery and radiation therapy, 5-and 10-year survival rates of 90% and 80% have been described23 but with a high morbidity (visual and endocrine deficits).
When complete resection can be performed (up to 90% in one series), there is a 7% risk of recurrence21. The risk of recurrence is much higher with partial resection. The risk of recurrence in subsequent pregnancies is not known to be increased: no familial cases have been reported.
Because of the poor prognosis, termination of pregnancy can be offered if the diagnosis is suspected early enough. The difficulty of making a differential diagnosis with teratoma is of little concern, since either tumor has an extremely poor prognosis. Cesarean section does not appear indicated even if the fetal head is enlarged.
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