Diagnosis and Treatment > Medication
Department of Endocrinology, Royal Hallamshire Hospital, University of Sheffield, Sheffield, UK
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Department of Endocrinology, Royal Hallamshire Hospital, University of Sheffield, Sheffield, UK
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Department of Endocrinology, Royal Hallamshire Hospital, University of Sheffield, Sheffield, UK
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Summary
The granulation pattern of somatotroph adenomas is well known to be associated with differing clinical and biochemical characteristics, and it has been shown that sparsely granulated tumours respond poorly to commonly used somatostatin receptor ligands (SRLs). We report a challenging case of acromegaly with a sparsely granulated tumour resistant to multiple modalities of treatment, ultimately achieving biochemical control with pasireotide. A 26-year-old lady presented with classical features of acromegaly, which was confirmed by an oral glucose tolerance test. Insulin-like growth factor 1 (IGF1) was 1710 µg/L (103–310 µg/L) and mean growth hormone (GH) was >600 U/L. MRI scan showed a 4 cm pituitary macroadenoma with suprasellar extension and right-sided cavernous sinus invasion. She underwent trans-sphenoidal pituitary surgery. Histology displayed moderate amounts of sparsely granular eosinophilic cytoplasm, staining only for GH. Postoperative investigations showed uncontrolled disease (IGF1:1474 µg/L, mean GH:228 U/L) and residual tumour in the cavernous sinus. She received external beam fractionated radiation. Over the years, she received octreotide LAR (up to 30 mg), lanreotide (up to 120 mg) two weekly, cabergoline, pegvisomant and stereotactic radiosurgery to no avail. Only pegvisomant resulted in an element of disease control; however, this had to be stopped due to abnormal liver function tests. Fifteen years after the diagnosis, she was started on pasireotide 40 mg monthly. Within a month, her IGF1 dropped and has remained within the normal range (103–310 µg/L). Pasireotide has been well tolerated, and there has been significant clinical improvement. Somatostatin receptor subtyping revealed a positivity score of two for both sst5 and sst2a subtypes.
Learning points:
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Age, size of the tumour, GH levels on presentation, histopathological type and the somatostatin receptor status of the tumour in acromegaly should be reviewed in patients who poorly respond to first-generation somatostatin receptor ligands.
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Tumours that respond poorly to first-generation somatostatin receptor ligands, especially sparsely granulated somatotroph adenomas, can respond to pasireotide and treatment should be considered early in the management of resistant tumours.
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Patients with membranous expression of sst5 are likely to be more responsive to pasireotide.
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Summary
A 54-year-old man had gastrinoma, parathyroid hyperplasia and pituitary tumor. His family history indicated that he might have multiple endocrine neoplasia type 1 (MEN1). MEN1 gene analysis revealed a heterozygous germline mutation (Gly156Arg). Therefore, we diagnosed him with MEN1. Endocrinological tests revealed that his serum prolactin (PRL) and plasma adrenocorticotropic hormone (ACTH) levels were elevated to 1699 ng/mL and 125 pg/mL respectively. Immunohistochemical analysis of the resected pancreatic tumors revealed that the tumors did not express ACTH. Overnight 0.5 and 8 mg dexamethasone suppression tests indicated that his pituitary tumor was a PRL-ACTH-producing plurihormonal tumor. Before transsphenoidal surgery, cabergoline was initiated. Despite no decrease in the volume of the pituitary tumor, PRL and ACTH levels decreased to 37.8 ng/mL and 57.6 pg/mL respectively. Owing to the emergence of metastatic gastrinoma in the liver, octreotide was initiated. After that, PRL and ACTH levels further decreased to 5.1 ng/mL and 19.7 pg/mL respectively. He died from liver dysfunction, and an autopsy of the pituitary tumor was performed. In the autopsy study, histopathological and immunohistochemical (IHC) analysis showed that the tumor was single adenoma and the cells were positive for ACTH, growth hormone (GH), luteinizing hormone (LH) and PRL. RT-PCR analysis showed that the tumor expressed mRNA encoding all anterior pituitary hormones, pituitary transcription factor excluding estrogen receptor (ER) β, somatostatin receptor (SSTR) 2, SSTR5 and dopamine receptor D (D2R). PRL-ACTH-producing tumor is a very rare type of pituitary tumor, and treatment with cabergoline and octreotide may be useful for controlling hormone levels secreted from a plurihormonal pituitary adenoma, as seen in this case of MEN1.
Learning points:
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Although plurihormonal pituitary adenomas were reported to be more frequent in patients with MEN1 than in those without, the combination of PRL and ACTH is rare.
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RT-PCR analysis showed that the pituitary tumor expressed various pituitary transcription factors and IHC analysis revealed that the tumor was positive for PRL, ACTH, GH and LH.
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Generally, the effectiveness of dopamine agonist and somatostatin analog in corticotroph adenomas is low; however, if the plurihormonal pituitary adenoma producing ACTH expresses SSTR2, SSTR5 and D2R, medical therapy for the pituitary adenoma may be effective.
