Diagnosis and Treatment > Signs and Symptoms
National University of Ireland, Galway, Ireland
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Summary
Symptomatic pituitary adenomas occur with a prevalence of approximately 0.1% in the general population. It is estimated that 5% of pituitary adenomas occur in a familial setting, either in isolated or syndromic form. Recently, loss-of-function mutations in genes encoding succinate dehydrogenase subunits (SDHx) or MYC-associated factor X (MAX) have been found to predispose to pituitary adenomas in co-existence with paragangliomas or phaeochromocytomas. It is rare, however, for a familial SDHx mutation to manifest as an isolated pituitary adenoma. We present the case of a pituitary lactotroph adenoma in a patient with a heterozygous germline SDHB mutation, in the absence of concomitant neoplasms. Initially, the adenoma showed biochemical response but poor tumour shrinkage in response to cabergoline; therefore, transsphenoidal surgery was performed. Following initial clinical improvement, tumour recurrence was identified 15 months later. Interestingly, re-initiation of cabergoline proved successful and the lesion demonstrated both biochemical response and tumour shrinkage. Our patient’s SDHB mutation was identified when we realised that her father had a metastatic paraganglioma, prompting genetic testing. Re-inspection of the histopathological report of the prolactinoma confirmed cells with vacuolated cytoplasm. This histological feature is suggestive of an SDHx mutation and should prompt further screening for mutations by immunohistochemistry and/or genetic testing. Surprisingly, immunohistochemistry of this pituitary adenoma demonstrated normal SDHB expression, despite loss of SDHB expression in the patient’s father’s paraganglioma.
Learning points:
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Pituitary adenomas may be the presenting and/or sole feature of SDHB mutation-related disease.
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SDHx mutated pituitary adenomas may display clinically aggressive behaviour and demonstrate variable response to medical treatment.
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Histological evidence of intracytoplasmic vacuoles in a pituitary adenoma might suggest an SDH-deficient tumour and should prompt further screening for SDHx mutations.
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Immunohistochemistry may not always predict the presence of SDHx mutations.
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Summary
Giant prolactinomas are rare tumours of the pituitary, which typically exceed 40 mm in their largest dimension. Impairment of higher cognitive function has been noted post-operatively after transcranial surgery and as a long-term consequence of the radiotherapy treatment. However, there has been little that is reported on such disturbances in relation to the tumour per se, and to our knowledge, there has been none in terms of responsivity to dopamine agonist therapy and shrinkage in these tumours. We present a case of successful restoration of severely impaired cognitive functions achieved safely after significant adenoma involution with medical treatment alone.
Learning points
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Giant prolactinomas can be present with profound cognitive defects.
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Dopamine agonists remain in the mainstay first-line treatment of giant prolactinomas.
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Mechanisms of the reversible cognitive impairment associated with giant prolactinoma treatment appear to be complex and remain open to further studies.
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Young patients with giant prolactinomas mandate genetic testing towards familial predisposition.
