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Pituitary carcinoma is a rare, malignant tumor of the pituitary gland, defined by the presence of craniospinal or systemic metastases from a histologically similar pituitary neoplasm.

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• Unlike benign pituitary adenomas, pituitary carcinomas are aggressive and account for <0.5% of all pituitary tumors.

Epidemiology

• Extremely rare: <150 cases reported in literature.
• Slight male predominance.
• Most patients present in the 4th to 7th decades.

Pathophysiology

Frequently arises from previously diagnosed invasive macroadenomas, especially those that are functional and resistant to therapy.

• Nearly all pituitary carcinomas arise from pre-existing adenomas, especially:
  • Prolactin-secreting tumors (~30–40%)
  • ACTH-secreting tumors (~25–30%)
• The transformation involves:
  • Progressive invasiveness
  • Accumulation of genetic mutations
  • Eventual metastasis via hematogenous or cerebrospinal fluid pathways

Clinical Features

• Symptoms of hormone hypersecretion (e.g., Cushing’s disease, hyperprolactinemia)
• Mass effect: visual disturbance, cranial nerve palsies
• Symptoms related to metastases:
  • Intracranial: leptomeningeal spread, spinal metastases
  • Extracranial: lung, liver, bone

Radiology

MR imaging: