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Open access

Melissa H Lee, Penelope McKelvie, Balasubramanian Krishnamurthy, Yi Yuen Wang and Carmela Caputo

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:

  • Acromegaly due to a mixed GH-secreting pituitary adenoma and intrasellar gangliocytoma is rare.

  • 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.

  • Surgical resection is usually sufficient to provide cure, without the need for adjuvant therapy.

  • These mixed tumours appear to have a good prognosis although the natural history is not well defined.

  • The pathogenesis of these mixed tumours remains debatable, and ongoing research is required.

Open access

Nikolaos Kyriakakis, Jacqueline Trouillas, Mary N Dang, Julie Lynch, Paul Belchetz, Márta Korbonits and Robert D Murray

Summary

A male patient presented at the age of 30 with classic clinical features of acromegaly and was found to have elevated growth hormone levels, not suppressing during an oral glucose tolerance test. His acromegaly was originally considered to be of pituitary origin, based on a CT scan, which was interpreted as showing a pituitary macroadenoma. Despite two trans-sphenoidal surgeries, cranial radiotherapy and periods of treatment with bromocriptine and octreotide, his acromegaly remained active clinically and biochemically. A lung mass was discovered incidentally on a chest X-ray performed as part of a routine pre-assessment for spinal surgery 5 years following the initial presentation. This was confirmed to be a bronchial carcinoid tumour, which was strongly positive for growth hormone-releasing hormone (GHRH) and somatostatin receptor type 2 by immunohistochemistry. The re-examination of the pituitary specimens asserted the diagnosis of pituitary GH hyperplasia. Complete resolution of the patient’s acromegaly was achieved following right lower and middle lobectomy. Seventeen years following the successful resection of the bronchial carcinoid tumour the patient remains under annual endocrine follow-up for monitoring of the hypopituitarism he developed after the original interventions to his pituitary gland, while there has been no evidence of active acromegaly or recurrence of the carcinoid tumour. Ectopic acromegaly is extremely rare, accounting for <1% of all cases of acromegaly. Our case highlights the diagnostic challenges differentiating between ectopic acromegaly and acromegaly of pituitary origin and emphasises the importance of avoiding unnecessary pituitary surgery and radiotherapy. The role of laboratory investigations, imaging and histology as diagnostic tools is discussed.

Learning points:

  • Ectopic acromegaly is rare, accounting for less than 1% of all cases of acromegaly.

  • Ectopic acromegaly is almost always due to extra-pituitary GHRH secretion, mainly from neuroendocrine tumours of pancreatic or bronchial origin.

  • Differentiating between acromegaly of pituitary origin and ectopic acromegaly can cause diagnostic challenges due to similarities in clinical presentation and biochemistry.

  • Serum GHRH can be a useful diagnostic tool to diagnose ectopic acromegaly.

  • Pituitary imaging is crucial to differentiate between a pituitary adenoma and pituitary hyperplasia, which is a common finding in ectopic acromegaly.

  • Diagnosing ectopic acromegaly is pivotal to avoid unnecessary interventions to the pituitary and preserve normal pituitary function.

Open access

Taiba Zornitzki, Hadara Rubinfeld, Lyudmila Lysyy, Tal Schiller, Véronique Raverot, Ilan Shimon and Hilla Knobler

Summary

Acromegaly due to ectopic GHRH secretion from a neuroendocrine tumor (NET) is rare and comprises <1% of all acromegaly cases. Herein we present a 57-year-old woman with clinical and biochemical features of acromegaly and a 6 cm pancreatic NET (pNET), secreting GHRH and calcitonin. Following surgical resection of the pancreatic tumor, IGF1, GH and calcitonin normalized, and the clinical features of acromegaly improved. In vitro studies confirmed that the tumor secreted large amounts of both GHRH and calcitonin, and incubation of pNET culture-derived conditioned media stimulated GH release from a cultured human pituitary adenoma. This is a unique case of pNET secreting both GHRH and calcitonin. The ability of the pNET-derived medium to stimulate in vitro GH release from a human pituitary-cell culture, combined with the clinical and hormonal remission following tumor resection, confirmed the ectopic source of acromegaly in this patient.

Learning points

  • Signs, symptoms and initial work-up of acromegaly due to ectopic GHRH secretion are similar to pituitary-dependent acromegaly. However, if no identifiable pituitary lesion is found, somatostatin receptor scan and further imaging (CT, MRI) should be performed.

  • Detection of GHRH in the blood and in the tumor-derived medium supports the diagnosis of ectopic GHRH secretion.

  • Functional bioactivity of pNET-secreted GHRH can be proved in vitro by releasing GH from human pituitary cells.