what is a craniopharyngioma

Intracranial Adamantinomatous-Papillary Epithelial Tumor

This comparatively rare central nervous system neoplasm arises near the pituitary gland and hypothalamus. While benign in the sense that it does not metastasize, its location can cause significant morbidity due to pressure on surrounding structures.

Histological Subtypes

  • Adamantinomatous: Characterized by palisading epithelium, stellate reticulum, and wet keratin. Calcifications and cystic components are frequently observed.
  • Papillary: Features pseudopapillae, uniform squamous epithelium, and a lack of calcification. More common in adults.

Etiology and Pathogenesis

The origins are thought to involve remnants of Rathke's pouch, an embryonic structure that gives rise to the anterior pituitary gland. Specific genetic mutations, such as those in the CTNNB1 gene (encoding beta-catenin), are commonly associated with the adamantinomatous variant.

Clinical Presentation

Symptoms vary depending on the size and location of the mass. Common manifestations include:

  • Visual Disturbances: Compression of the optic chiasm can lead to bitemporal hemianopia (loss of peripheral vision).
  • Endocrine Dysfunction: Disruption of the pituitary gland can cause hormonal imbalances, such as growth hormone deficiency, diabetes insipidus, or hypogonadism.
  • Headaches: Increased intracranial pressure can result in persistent headaches.
  • Nausea and Vomiting: Due to increased intracranial pressure.
  • Developmental Delays: In children, this tumor may interfere with normal growth and development.

Diagnosis

Diagnosis typically involves a combination of:

  • Neurological Examination: To assess visual fields, cranial nerve function, and motor skills.
  • Endocrine Evaluation: Blood tests to measure hormone levels.
  • Neuroimaging: Magnetic resonance imaging (MRI) and computed tomography (CT) scans are used to visualize the tumor and assess its size and location. Calcifications are often visible on CT scans.
  • Biopsy: Histopathological examination of a tissue sample obtained through surgery confirms the diagnosis and subtype.

Treatment

The primary treatment is surgical resection. Gross total resection (complete removal of the tumor) is the ideal goal, but it may not always be possible due to the tumor's proximity to critical structures.

  • Surgery: Surgical approaches include transcranial and transsphenoidal techniques.
  • Radiation Therapy: Used as adjuvant therapy after surgery to control residual tumor growth or as primary therapy for tumors that cannot be completely resected. Options include external beam radiation therapy (EBRT) and stereotactic radiosurgery (SRS).
  • Chemotherapy: Has a limited role, typically reserved for recurrent or progressive tumors not amenable to surgery or radiation.
  • Intracystic Therapy: For cystic masses, injections of radioactive isotopes (e.g., phosphorus-32) directly into the cyst can be used to reduce its size.

Prognosis

The prognosis varies depending on the extent of resection and the tumor's location. Recurrence is common, even after gross total resection. Long-term management often involves endocrine replacement therapy to address hormonal deficiencies.