Inferior petrosal sinus sampling

Inferior petrosal sinus sampling

Inferior petrosal sinus sampling (IPSS) is an invasive procedure in which adrenocorticotropic hormone (ACTH) levels are sampled from the veins that drain the pituitary gland; these levels are then compared with the ACTH levels in the peripheral blood to determine whether a pituitary tumor(as opposed to an ectopic source of ACTH) is responsible for ACTH-dependent Cushing syndrome. IPSS can also be used to establish on which side of the pituitary gland the tumor is located.

Bilateral inferior petrosal sinus sampling (BIPSS) is considered the gold standard test for anatomical localization for Cushing’s disease where radiology has been inconclusive1).

In a metaanalysis of 21 studies, the overall sensitivity and specificity of BIPSS were found to be 96% and 100% respectively 2).

Anatomical localization of pituitary adenoma can be challenging in adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome, and bilateral inferior petrosal sinus sampling (BIPSS) is considered gold standard in this regard. Stimulation using corticotropin releasing hormone(CRH) improves the sensitivity of BIPSS.

In essence, it tests to see the source of the raised ACTH levels in a patient with diagnosed Cushing’s syndrome and high or normal serum ACTH levels. The inferior petrosal sinus is where the pituitary gland drains. Therefore, a sample from here showing raised ACTH compared to the periphery suggests that it is a pituitary cause of Cushing’s, i.e. Cushing’s disease. Equivocal levels of ACTH indicate ectopic or Paraneoplastic Cushing’s Syndrome. The sample is usually taken after administration of Corticotropin-releasing hormone or, more recently, DDAVP, which have been shown to increase ACTH production in active ACTH-producing pituitary tumors. Increasingly, it is known as a gold-standard method for diagnosing Cushing’s disease.

To increase the sensitivity, the sampling is repeated after peripheral administration of oCRH. Following this a peak central to peripheral plasma ACTH ratio of 3 or more occurring 3-5 minutes after oCRH stimulation is highly indicative of Cushing disease.

see Inferior petrosal sinus sampling with desmopressin.


Asymmetric inferior petrosal sinuses (IPS) are not infrequently encountered during bilateral IPS sampling. There is little data on whether IPS symmetry influences success in predicting the adenoma side in patients with ACTH-dependent Cushing’s syndrome (CS).

BIPSS was performed in 38 patients with a mean age of 45 ± 15 years. The overall technical success rate was 97% for bilateral cannulation. Asymmetric IPS were observed in 11 (39%) patients with Cushing’s disease (CD). A side-to-side ACTH ratio was not significantly different between patients with symmetric outflow and those with asymmetric outflow at baseline (8.6 ± 2.7 versus 16.4 ± 6.0; P = 0.45), but ratios were significantly different after ovine corticotropin-releasing hormone (oCRH) stimulation (6.0 ± 2.5 versus 35.7 ± 22.5; P = 0.03). BIPSS correctly predicted the side of the adenoma in 25 (96%) patients with CD. Prediction was better when the venous outflow was symmetric (100%) rather than asymmetric (93%), although the difference was not significant (P = 0.42). Remission from CS was achieved in 32 patients (87%), independent of the symmetry of IPS.

Bearing in mind the sample size of this audit, asymmetric IPS at least do not seem to diminish the accuracy of diagnosis of ACTH-dependent CS, nor do they influence the clinical outcome 3).

Procedure

Most often, BIPSS is performed by sampling ACTH peripherally and from both IPSs before and after CRH (Acthrel; Ben Venue Laboratories, Ohio, USA) administration. In the US, CRH is typically given at a dose of 1 μg/kg, by slow intravenous push over 30 seconds; in other countries, a typical dose is 100 μg. Conscious sedation is preferred to allow for the monitoring of symptoms suggesting complications. A 6-French sheath is advanced into the right femoral vein, and a five-French sheath into the left femoral vein. The larger sheath allows for sampling from the common femoral vein, while a 5-French catheter is in place distally. Subsequently, 3,000–5,000 units of heparin are given to prevent cavernous sinus and other venous thrombosis.

Next, 5-French Davis catheters are advanced through each femoral vein sheath into the contralateral internal jugular vein, followed by 2.8-French microcatheters, directed medially at the C1–2 level to access the orifice of the IPS 4). without entering clival veins 5). Both catheters are positioned symmetrically.

Once catheter positions are confirmed, two baseline ACTH specimens are collected from the right femoral sheath (peripheral specimen) and both IPSs. CRH is then administered peripherally. Repeat ACTH sampling from the periphery and both IPSs is obtained 3 minutes, 5 minutes, 10 minutes, and 15 minutes after the injection of CRH. Samples are collected in tubes that are placed on ice before transport to the laboratory. Upon completion of sampling, both femoral sheaths are removed, and manual compression is used to obtain hemostasis before transferring patients to the recovery room for a rest of approximately 4 hours.

References

1)

Lad SP, Patil CG, Laws ER Jr, Katznelson L. The role of inferior petrosal sinus sampling in the diagnostic localization of Cushing’s disease. Neurosurg Focus. 2007;23:E2.
2)

Newell-Price J, Trainer P, Besser M, Grossman A. The diagnosis and differential diagnosis of Cushing’s syndrome and pseudo-Cushing’s states. Endocr Rev. 1998;19:647–72.
3)

Andereggen L, Gralla J, Schroth G, Mordasini P, Andres RH, Widmer HR, Luedi MM, Kellner F, Beck J, Mariani L, Ozdoba C, Christ E. Influence of inferior petrosal sinus drainage symmetry on detection of adenomas in Cushing’s syndrome. J Neuroradiol. 2019 Jun 19. pii: S0150-9861(19)30233-0. doi: 10.1016/j.neurad.2019.05.004. [Epub ahead of print] PubMed PMID: 31228539.
4)

Tomycz ND, Horowitz MB. Inferior petrosal sinus sampling in the diagnosis of sellar neuropathology. Neurosurg Clin N Am. 2009 Jul;20(3):361-7. doi: 10.1016/j.nec.2009.01.003. Review. PubMed PMID: 19778704.
5)

Doppman JL, Oldfield E, Krudy AG, Chrousos GP, Schulte HM, Schaaf M, Loriaux DL. Petrosal sinus sampling for Cushing syndrome: anatomical and technical considerations. Work in progress. Radiology. 1984 Jan;150(1):99-103. PubMed PMID: 6316418.

Dopamine agonist resistant lactotroph adenoma

Dopamine agonist resistant lactotroph adenoma

While dopamine agonists are a primary method of therapeutic treatment for Lactotroph adenoma, the rate of resistance to these drugs continues to increase each year.

Surgery is typically indicated for patients who are resistant to medical therapy or intolerant of its adverse side effects, or are experiencing progressive tumor growth. Surgical resection can also be considered as a primary treatment for those with smaller focal tumors where a biochemical cure can be expected as an alternative to lifelong dopamine agonist treatment. Stereotactic radiosurgery also serves as an option for those refractory to medical and surgical therapy 1).


Coopmans et al., reported a patient with an highly aggressive, dopamine-resistant prolactinoma, who only achieved biochemical and tumor control during pasireotide long-acting release (PAS-LAR) therapy , a second-generation somatostatin receptor ligand (SRL). Interestingly, cystic degeneration, tumor cell necrosis, or both was observed after PAS-LAR administration suggesting an antitumor effect. This case shows that PAS-LAR therapy holds clinical potential in selective aggressive, dopamine-resistant prolactinomas that express somatostatin receptor 5 and appears to be a potential new treatment option before starting temozolomide. In addition, PAS-LAR therapy may induce cystic degeneration, tumor cell necrosis, or both in prolactinomas 2).


During previous long-term clinical investigations, Hu et al., from Department of Neurosurgery and Pituitary Tumor Center, The First Affiliated Hospital, Sun Yat-sen University, GuangzhouChina, found that partial resistant prolactinomas exhibited significantly more fibrosis than did sensitive adenomas, suggesting a role of fibrosis in their drug resistance. Furthermore, resistant adenomas with extensive fibrosis mainly express type I and type III collagens. Since TGF-β1 is the key factor in the initiation and development of tissue fibrosis, including in the pituitary, in this study, they aimed to determine whether TGF-β1 mediated fibrosis in prolactinomas and whether fibrosis was related to prolactinoma drug resistance. Using immunochemistry and western blotting, they found that the TGF-β1/Smad3 signaling pathway-related proteins were elevated in resistant prolactinoma specimens with high degrees of fibrosis compared to levels in sensitive samples, suggesting that this pathway may play a role in prolactinoma fibrosis. In vitro, TGF-β1 stimulation promoted collagen expression in normal HS27 fibroblasts. Furthermore, the sensitivity of rat prolactinoma MMQ cells to bromocriptine decreased when they were co-cultured with HS27 cells treated with TGF-β1. The TGF-β1/Smad3 signaling-specific inhibitor SB431542 counteracted these effects, indicating that TGF-β1/Smad3-mediated fibrosis was involved in the drug-resistant mechanisms of prolactinomas. These results indicate that SB431542 may serve as a promising novel treatment for preventing fibrosis and further improving the drug resistance of prolactinoma3).

References

1)

Wong A, Eloy JA, Couldwell WT, Liu JK. Update on prolactinomas. Part 2: Treatment and management strategies. J Clin Neurosci. 2015 Oct;22(10):1568-74. doi: 10.1016/j.jocn.2015.03.059. Epub 2015 Aug 1. Review. PubMed PMID: 26243714.
2)

Coopmans EC, van Meyel SWF, Pieterman KJ, van Ipenburg JA, Hofland L, Donga E, Daly AF, Beckers A, Van der Lely AJ, Neggers SJCMM. Excellent response to pasireotide therapy in an aggressive and dopamine-resistant prolactinoma. Eur J Endocrinol. 2019 Jun 1. pii: EJE-19-0279.R1. doi: 10.1530/EJE-19-0279. [Epub ahead of print] PubMed PMID: 31167168.
3)

Hu B, Mao Z, Jiang X, He D, Wang Z, Wang X, Zhu Y, Wang H. Role of TGF-β1/Smad3-mediated fibrosis in drug resistance mechanism of prolactinoma. Brain Res. 2018 Jul 26. pii: S0006-8993(18)30408-6. doi: 10.1016/j.brainres.2018.07.024. [Epub ahead of print] PubMed PMID: 30055965.

X-linked acrogigantism

X-linked acrogigantism

X-linked acrogigantism (X-LAG), a condition of infant-onset acrogigantism marked by elevated GHIGF-1, and prolactin (PRL), is extremely rare. Thirty-three cases, including three kindreds, have been reported. These patients have pituitary adenomas that are thought to be mixed lactotrophs and somatotrophs.

Pituitary tumors are undergoing a transformation in histopathologic and molecular classification, coincident with the continued refinement of increasingly powerful methods of genomic annotation and discovery.

Sporadic pituitary adenomas are associated with relatively few recurrent somatic mutations. Recurrent mutations occur largely in subsets of hormone-producing tumors, including GNAS and GPR101 in somatotroph adenomas and USP8 in corticotroph adenomas. Additionally, they manifest with a dichotomous signature of copy number alterations, ranging from almost none to widespread genome instability, while microduplication of chromosome Xq26.3, containing the GNAS gene, defines X-linked acrogigantism. Papillary craniopharyngiomas are defined by BRAF V600E mutations while β-catenin alterations characterize adamantinomatous craniopharyngiomas. Genomic annotation of pituitary tumors is defining increasing subsets of neuroendocrine adenohypophyseal tumors and craniopharyngiomas, offering rationale-based pharmacologic targets and potential biomarkers for clinical outcome 1).


Non-syndromic pituitary gigantism can result from AIP mutations or the identified Xq26.3 microduplication causing X-linked acrogigantism (XLAG). Within Xq26.3, GPR101 is believed to be the causative gene, and the c.924G > C (p.E308D) variant in this orphan G protein-coupled receptor has been suggested to play a role in the pathogenesis of acromegaly.We studied 153 patients (58 females and 95 males) with pituitary gigantism. AIP mutation-negative cases were screened for GPR101 duplication through copy number variation droplet digital PCR and high-density aCGH. The genetic, clinical and histopathological features of XLAG patients were studied in detail. 395 peripheral blood and 193 pituitary tumor DNA samples from acromegaly patients were tested for GPR101 variants.We identified 12 patients (10 females and 2 males; 7.8 %) with XLAG. In one subject, the duplicated region only contained GPR101, but not the other three genes in found to be duplicated in the previously reported patients, defining a new smallest region of overlap of duplications. While females presented with germline mutations, the two male patients harbored the mutation in a mosaic state. Nine patients had pituitary adenomas, while three had hyperplasia. The comparison of the features of XLAG, AIP-positive and GPR101&AIP-negative patients revealed significant differences in sex distribution, age at onset, height, prolactin co-secretion and histological features. The pathological features of XLAG-related adenomas were remarkably similar. These tumors had a sinusoidal and lobular architecture. Sparsely and densely granulated somatotrophs were admixed with lactotrophs; follicle-like structures and calcifications were commonly observed. Patients with sporadic of familial acromegaly did not have an increased prevalence of the c.924G > C (p.E308D) GPR101 variant compared to public databases.In conclusion, XLAG can result from germline or somatic duplication of GPR101. Duplication of GPR101 alone is sufficient for the development of XLAG, implicating it as the causative gene within the Xq26.3 region. The pathological features of XLAG-associated pituitary adenomas are typical and, together with the clinical phenotype, should prompt genetic testing 2).

Case reports

The patient’s mother, diagnosed with acrogigantism at 21 months, underwent pituitary tumor excision at 24 months. For over 30 years, stable PRL, GH, and IGF-1 concentrations and serial imaging studies indicated no tumor recurrence. During pre-conception planning, X-LAG was diagnosed: single-nucleotide polymorphism (SNP) microarray showed chromosome Xq26.3 microduplication. After conception, SNP microarray on a chorionic villus sample showed the same microduplication in the fetus, confirming familial X-LAG. The infant grew rapidly with rising PRL, GH, and IGF-1 concentrations and an enlarging suprasellar pituitary mass, despite treatment with bromocriptine. At 15 months, he underwent tumor resection. The pituitary adenoma resembled the mother’s pituitary adenoma, with tumor cells arranged in trabeculae and glandular structures. In both cases, many tumor cells expressed PRL, GH, and PIT1. Furthermore, the tumor expressed other lineage-specific transcription factors, as well as SOX2 and OCT4, demonstrating the multipotentiality of X-LAG tumors. Both showed an elevated Ki-67 proliferation index-5.6% (mother) and 8.5% (infant)-the highest reported in X-LAG.

This is the first prenatally diagnosed case of X-LAG. Clinical follow-up and biochemical evaluation have provided insight into the natural history of this disease. Expression of stem cell markers and several cell lineage-specific transcription factors suggests that these tumors are multipotential. 3).

References

1)

Bi WL, Larsen AG, Dunn IF. Genomic Alterations in Sporadic Pituitary Tumors. Curr Neurol Neurosci Rep. 2018 Feb 2;18(1):4. doi: 10.1007/s11910-018-0811-0. Review. PubMed PMID: 29396598.
2)

Iacovazzo D, Caswell R, Bunce B, Jose S, Yuan B, Hernández-Ramírez LC, Kapur S, Caimari F, Evanson J, Ferraù F, Dang MN, Gabrovska P, Larkin SJ, Ansorge O, Rodd C, Vance ML, Ramírez-Renteria C, Mercado M, Goldstone AP, Buchfelder M, Burren CP, Gurlek A, Dutta P, Choong CS, Cheetham T, Trivellin G, Stratakis CA, Lopes MB, Grossman AB, Trouillas J, Lupski JR, Ellard S, Sampson JR, Roncaroli F, Korbonits M. Germline or somatic GPR101 duplication leads to X-linked acrogigantism: a clinico-pathological and genetic study. Acta Neuropathol Commun. 2016 Jun 1;4(1):56. doi: 10.1186/s40478-016-0328-1. PubMed PMID: 27245663; PubMed Central PMCID: PMC4888203.
3)

Wise-Oringer BK, Zanazzi GJ, Gordon RJ, Wardlaw SL, William C, Anyane-Yeboa K, Chung WK, Kohn B, Wisoff JH, David R, Oberfield SE. Familial X-Linked Acrogigantism: Postnatal Outcomes and Tumor Pathology in a Prenatally Diagnosed Infant and His Mother. J Clin Endocrinol Metab. 2019 Jun 5. pii: jc.2019-00817. doi: 10.1210/jc.2019-00817. [Epub ahead of print] PubMed PMID: 31166600.
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