Craniopharyngioma

Nagi, Sonia

doi:10.1007/978-3-319-29043-0_22

Sonia Nagi MD⁵

2186 Accesses

Abstract

Craniopharyngioma is an epithelial tumor, classified as WHO grade 1. Although histologically benign, craniopharyngiomas are aggressive neoplasms, and recurrences are common because complete surgical resection is difficult. They represent approximately 5 % of all intracranial tumors. Craniopharyngiomas are derived from remnants of the Rathke pouch and can occur anywhere along the course of the craniopharyngeal duct, from the nasopharynx to the third ventricle. They are usually sporadic. Rare cases of adamantinous craniopharyngiomas have been associated with Gardner syndrome, a variant of familial adenomatous polyposis. Craniopharyngiomas are characterized by a bimodal age distribution, with a main peak in children (5–14 years) and a second peak in adults (fifth to seventh decade). They most commonly involve the suprasellar and sellar area (75 %), where they are either anterior or posterior to the optic chiasm. In fewer cases, their location is purely suprasellar (20 %) or entirely intrasellar (5 %). There are two histologic subtypes: the adamantinous type, most common form, typically seen in children and adolescents; and the papillary type, seen almost exclusively in adults. Adamantinous craniopharyngiomas are usually lobulated and cystic tumors, containing a dark greenish brown fluid. These cysts contain variable amounts of cholesterol, keratin, protein, methemoglobin, and necrotic debris, which account for their variable appearance on MRI. They are usually associated with calcification and often demonstrate local brain invasion, being adherent to adjacent vessels and nerves. Papillary craniopharyngiomas are generally well-circumscribed, predominantly solid tumors. The solid component may rarely contain small cystic areas or calcifications. The third ventricle is a common location of this subtype. Clinical symptoms are variable, on account of the variable location. Headache, visual field defects, decreased visual acuity, and hormone disturbance are the common clinical symptoms in the suprasellar location. The most common endocrine dysfunctions encountered in children are growth retardation and delayed or precocious puberty. Global hypopituitarism, hyperprolactinemia, and diabetes insipidus are the other endocrine disorders encountered. Less commonly, patients may present with cognitive impairment or personality change.

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Craniopharyngiomas

Craniopharyngioma

Histopathology and Molecular Pathology of Craniopharyngioma in Adults

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Craniopharyngioma is an epithelial tumor, classified as WHO grade 1. Although histologically benign, craniopharyngiomas are aggressive neoplasms, and recurrences are common because complete surgical resection is difficult. They represent approximately 5 % of all intracranial tumors. Craniopharyngiomas are derived from remnants of the Rathke pouch and can occur anywhere along the course of the craniopharyngeal duct, from the nasopharynx to the third ventricle. They are usually sporadic. Rare cases of adamantinous craniopharyngiomas have been associated with Gardner syndrome, a variant of familial adenomatous polyposis. Craniopharyngiomas are characterized by a bimodal age distribution, with a main peak in children (5–14 years) and a second peak in adults (fifth to seventh decade). They most commonly involve the suprasellar and sellar area (75 %), where they are either anterior or posterior to the optic chiasm. In fewer cases, their location is purely suprasellar (20 %) or entirely intrasellar (5 %). There are two histologic subtypes: the adamantinous type, most common form, typically seen in children and adolescents; and the papillary type, seen almost exclusively in adults. Adamantinous craniopharyngiomas are usually lobulated and cystic tumors, containing a dark greenish brown fluid. These cysts contain variable amounts of cholesterol, keratin, protein, methemoglobin, and necrotic debris, which account for their variable appearance on MRI. They are usually associated with calcification and often demonstrate local brain invasion, being adherent to adjacent vessels and nerves. Papillary craniopharyngiomas are generally well-circumscribed, predominantly solid tumors. The solid component may rarely contain small cystic areas or calcifications. The third ventricle is a common location of this subtype. Clinical symptoms are variable, on account of the variable location. Headache, visual field defects, decreased visual acuity, and hormone disturbance are the common clinical symptoms in the suprasellar location. The most common endocrine dysfunctions encountered in children are growth retardation and delayed or precocious puberty. Global hypopituitarism, hyperprolactinemia, and diabetes insipidus are the other endocrine disorders encountered. Less commonly, patients may present with cognitive impairment or personality change.

Adamantinous craniopharyngiomas classically occur in childhood or adolescence and typically present with three components: solid, cystic, and calcified portions, which occupy the suprasellar cistern (Figs. 22.1, 22.2, 22.3, and 22.4). The cystic component is single or multiple, and usually hyperintense on T1, T2, and FLAIR weighted images because of the presence of proteinaceous liquid. Less commonly, a CSF-like signal pattern can be seen in huge craniopharyngiomas with a thick wall enhancement. The solid component has variable signal intensities and shows contrast enhancement. Small necrotic areas account for its inhomogeneous signal before and after contrast administration. Calcifications are common (90 % of cases) and are better demonstrated by T2* sequence. However, their confirmation by a CT scan is sometimes necessary. Lipid resonances are usually detected in proton MR spectroscopy. Huge craniopharyngiomas can extend in all directions. The sella is often enlarged and may be eroded.

Papillary craniopharyngiomas usually appear as a solid or mixed, predominantly solid and cystic, spherical tumor in the suprasellar region (Fig. 22.4). They are characterized by a more upward growth toward the third ventricle. The solid parts classically show isointense signal intensity on T1 and T2 WI, with a hypointense signal on DWI with increased apparent diffusion coefficient reflecting the low-grade character. They present homogeneous or reticular enhancement because of their small necrotic areas. They less frequently contain calcifications. Nevertheless, their imaging features are nonspecific, and differential diagnosis is based on the age of the patient and the location of the tumor. Surgical removal is easier in this subtype than in the adamantinous type. Peritumoral edema spreading along the optic tracts was initially considered to be specific to craniopharyngiomas. Similar optic tract edema has been described since then in other parasellar tumors such as adenomas, germ cell tumors, gliomas, meningiomas, and lymphomas. This could be related to distension of perivascular spaces, which represent a drainage route of interstitial fluid into the subarachnoid space, their outflow pathway into the subarachnoid spaces being blocked by suprasellar tumor (Figs. 22.4 and 22.5). Occasionally, craniopharyngiomas are located in the third ventricle (Fig. 22.6). Rare locations include posterior fossa, sphenoid bone, and nasopharynx. Distant spread of craniopharyngioma is a rare complication that occurs independently of the subtype. Locations include cerebral hemispheres, posterior fossa, brainstem, basal ganglia, and lumbar spine. The mechanism is poorly understood, but most cases are thought to result from spread along the surgical path (Fig. 22.7). Metastatic leptomeningeal craniopharyngiomas have been reported, as a result of dissemination along CSF pathways (Fig. 22.8). Craniopharyngiomas with multiple recurrences and malignant transformations have been reported. The key factor associated with craniopharyngioma recurrence is the quality of surgical resection. Adhesion or encasement of adjacent cranial nerves or vessels (Fig. 22.7) significantly increases surgical morbidity. Differential diagnosis includes Rathke cleft cyst (Fig. 22.9), pituitary adenoma (Fig. 22.10), dermoid cyst, epidermoid cyst, teratoma, and pilomyxoid astrocytoma. Treatment usually consists of surgical resection with or without adjuvant radiation therapy.