Diagnosis and Treatment > Signs and Symptoms
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Summary
Early-onset acromegaly causing gigantism is often associated with aryl-hydrocarbon-interacting receptor protein (AIP) mutation, especially if there is a positive family history. A15y male presented with tiredness and visual problems. He was 201 cm tall with a span of 217 cm. He had typical facial features of acromegaly, elevated IGF-1, secondary hypogonadism and a large macroadenoma. His paternal aunt had a history of acromegaly presenting at the age of 35 years. Following transsphenoidal surgery, his IGF-1 normalized and clinical symptoms improved. He was found to have a novel AIP mutation destroying the stop codon c.991T>C; p.*331R. Unexpectedly, his father and paternal aunt were negative for this mutation while his mother and older sister were unaffected carriers, suggesting that his aunt represents a phenocopy.
Learning points:
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Typical presentation for a patient with AIP mutation with excess growth and eunuchoid proportions.
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Unusual, previously not described AIP variant with loss of the stop codon.
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Phenocopy may occur in families with a disease-causing germline mutation.
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Summary
Most cases of acromegaly are due to growth hormone (GH)-secreting pituitary adenomas arising from somatotroph cells. Mixed pituitary adenoma and gangliocytoma tumours are rare and typically associated with hormonal hypersecretion, most commonly GH excess. Differentiating these mixed tumours from conventional pituitary adenomas can be difficult pre-operatively, and careful histological analysis after surgical resection is key to differentiating the two entities. There is little literature addressing the possible mechanisms for the development of mixed pituitary adenoma–gangliocytomas; however, several hypotheses have been proposed. It still remains unclear if these mixed tumours differ from a clinical perspective to pituitary adenomas; however, the additional neural component of the gangliocytoma does not appear to modify the aggressiveness or risk of recurrence after surgical resection. We report a unique case of acromegaly secondary to a mixed GH-secreting pituitary adenoma, co-existing with an intrasellar gangliocytoma.
Learning points:
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Acromegaly due to a mixed GH-secreting pituitary adenoma and intrasellar gangliocytoma is rare.
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These mixed tumours cannot be distinguished easily from ordinary pituitary adenomas on the basis of clinical, endocrine or neuroradiologic findings, and histological analysis is required for a definitive diagnosis.
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Surgical resection is usually sufficient to provide cure, without the need for adjuvant therapy.
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These mixed tumours appear to have a good prognosis although the natural history is not well defined.
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The pathogenesis of these mixed tumours remains debatable, and ongoing research is required.
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Summary
Co-secretion of growth hormone (GH) and prolactin (PRL) from a single pituitary adenoma is common. In fact, up to 25% of patients with acromegaly may have PRL co-secretion. The prevalence of acromegaly among patients with a newly diagnosed prolactinoma is unknown. Given the possibility of mixed GH and PRL co-secretion, the current recommendation is to obtain an insulin-like growth factor-1 (IGF-1) in patients with prolactinoma at the initial diagnosis. Long-term follow-up of IGF-1 is not routinely done. Here, we report two cases of well-controlled prolactinoma on dopamine agonists with the development of acromegaly 10–20 years after the initial diagnoses. In both patients, a mixed PRL/GH-cosecreting adenoma was confirmed on the pathology examination after transsphenoidal surgery (TSS). Therefore, periodic routine measurements of IGF-1 should be considered regardless of the duration and biochemical control of prolactinoma.
Learning points:
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Acromegaly can develop in patients with well-controlled prolactinoma on dopamine agonists.
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The interval between prolactinoma and acromegaly diagnoses can be several decades.
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Periodic screening of patients with prolactinoma for growth hormone excess should be considered and can lead to an early diagnosis of acromegaly before the development of complications.
