Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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March 2, 2017
Pituitary Carcinoma
- Background:
- Pituitary carcinomas are only defined by the presence of CSF or systemic metastases. They are exceedingly rare, with an incidence of 0.2% of symptomatic pituitary tumors, but represent a particular challenge in clinical practice.
- Clinical Presentation:
- Pituitary carcinomas develop with equal frequency in both sexes at a mean age of 44 years.
- Latency period of 7 years after the diagnosis of a pituitary tumor, depending on the subtype
- Presenting symptoms include visual impairment, presenting either as visual field loss or a decreased visual acuity, and/or cranial nerve palsies
- The presence of unusual symptoms in a pituitary tumor (e.g., hearing loss, ataxia, and/or motor impairment) should alert physicians to the diagnosis.
- Key Diagnostic Features:
- The primary tumor must be identified histologically as a pituitary tumor.
- An alternative primary tumor has to be excluded.
- Discontinuous spread in the form of single or multiple nodular subarachnoid metastatic deposits, occasionally invading the underlying brain or overlying dura
- Single or multiple systemic metastasis, broadly similar and grossly indistinguishable from metastases of carcinomas arising in other organs
- The structural features or immunohistochemical marker expression of the metastases should correspond or be similar to those of the primary pituitary tumor.
- Differential Diagnoses:
- Radiation-associated tumors: Secondary tumors associated with radiation therapy as meningiomas and schwannomas are increasingly recognized as a delayed complication. Although the incidence is relatively rare (approximately 1%), in general, a radiation-associated tumor occurs in the radiation field having a relatively long latency period.
- Metastasis of other tumors: Uncommon in the pituitary gland and accounts for only 1.8% of all metastases and 1% of all pituitary cancers; difficult to diagnose because most are small and clinically silent; most common primary malignancies are breast cancer in females and lung cancer in males; intracranial metastases from other primary tumors are less frequent.
- Radiation-induced cavernous malformation: Late complications of RT, usually occurring in patients with a history of RT during childhood; latency periods vary from a few months to several decades; most cavernous malformations have a distinctive “popcorn” appearance of their nidus, with little or no surrounding edema and blooming artefact in the T2* gradient sequence.
- Treatment:
- Treatment options include surgery, external radiotherapy, medical treatment, and peptide receptor radionuclide therapy.
- Current therapeutic modalities are mainly palliative, and once metastases develop, the prognosis of these tumors is relatively poor.