Pituitary adenoma associated with pheochromocytoma/paraganglioma: A new form of multiple endocrine neoplasia

Adrenal Incidentalomas and Other Endocrine-Related Adenomas: How Much Does Cortisol Secretion Matter?

Background: Adrenal incidentalomas (AI) are frequent findings in clinical practice. About 40% of AIs are associated with hypercortisolism of variable severity. Although mild autonomous cortisol secretion (MACS) has been associated with the impaired clinical outcome of several diseases, its effect on the development of benign neoplasms is unknown. Aim: To compare the prevalence of adenomas (thyroid, parathyroid, pituitary and other locations) in patients with nonfunctioning AIs (NFAIs) and MACS. Methods: A multicenter, retrospective study of patients with AIs evaluated in four tertiary hospitals was performed. Results: A total of 923 patients were included. Most patients were male (53.6%), with a mean age at diagnosis of 62.4 ± 11.13 years; 21.7% presented with bilateral AIs. MACS was observed in 29.9% (n = 276) of patients, while 69.9% (n = 647) were NFAIs. Adenomas in locations other than the adrenal gland were observed in 36% of the studied population, with a similar distribution in patients with MACS and NFAIs (33% vs. 32%; p > 0.05). There were no statistically significant differences in the prevalence of pituitary, thyroid, parathyroid or other endocrine-related adenomas between both groups, but the prevalence of metabolic comorbidities and mortality was increased in patients with MACS, specifically in patients with thyroid and other endocrine-related adenomas (p < 0.05). Conclusions: Adenomas in locations other than the adrenal glands occur in one third of patients with AIs. Mild autonomous hypercortisolism does not affect the prevalence of other endocrine-related adenomas but is associated with increased metabolic comorbidities and mortality, especially in patients with thyroid adenomas and adenomas in other locations.

[Rare forms of hereditary endocrine neoplasia: co-existence of pituitary adenoma and pheochromocytoma/paraganglioma]

Functioning pituitary adenomas and pheochromocytomas/paragangliomas are rare in the general population. Pituitary adenomas occur in the familial setting in approximately 5% of cases, whereas pheochromocytomas/paragangliomas can be hereditary in 30-40% of cases. Hereditary syndromes associated with pituitary adenomas include multiple endocrine neoplasia types 1 and 4, familial isolated pituitary adenomas, and Carney complex. Hereditary syndromes associated with pheochromocytomas/paragangliomas and genes, mutations in which predispose to their development, are more numerous. The first clinical descriptions of the co-occurrence of pituitary adenoma and pheochromocytoma/paraganglioma in one patient date back to the mid 20th century, however delineating such a co-occurrence into a particular syndrome («3PAs» (pituitary adenoma, pheochromocytoma, paraganglioma)) was suggested only in 2015. To date, approximately 100 cases of such a co-occurrence have been described in the literature. Mutations in genes encoding subunits of succinate dehydrogenase complex II (SDHx) are revealed in the majority of cases, much less common are mutations in MAX, MEN1 and some other genes. This review summarizes the current information on the «3PAs» syndrome.

SDHx mutation and pituitary adenoma: can in vivo 1H-MR spectroscopy unravel the link?

Germline mutations in genes encoding succinate dehydrogenase (SDH) are frequently involved in pheochromocytoma/paraganglioma (PPGL) development and were implicated in patients with the '3PAs' syndrome (associating pituitary adenoma (PA) and PPGL) or isolated PA. However, the causality link between SDHx mutation and PA remains difficult to establish, and in vivo tools for detecting hallmarks of SDH deficiency are scarce. Proton magnetic resonance spectroscopy (1H-MRS) can detect succinate in vivo as a biomarker of SDHx mutations in PGL. The objective of this study was to demonstrate the causality link between PA and SDH deficiency in vivo using 1H-MRS as a novel noninvasive tool for succinate detection in PA. Three SDHx-mutated patients suffering from a PPGL and a macroprolactinoma and one patient with an apparently sporadic non-functioning pituitary macroadenoma underwent MRI examination at 3 T. An optimized 1H-MRS semi-LASER sequence (TR = 2500 ms, TE = 144 ms) was employed for the detection of succinate in vivo. Succinate and choline-containing compounds were identified in the MR spectra as single resonances at 2.44 and 3.2 ppm, respectively. Choline compounds were detected in all the tumors (three PGL and four PAs), while a succinate peak was only observed in the three macroprolactinomas and the three PGL of SDHx-mutated patients, demonstrating SDH deficiency in these tumors. In conclusion, the detection of succinate by 1H-MRS as a hallmark of SDH deficiency in vivo is feasible in PA, laying the groundwork for a better understanding of the biological link between SDHx mutations and the development of these tumors.

3P association (3PAs): Pituitary adenoma and pheochromocytoma/paraganglioma. A heterogeneous clinical syndrome associated with different gene mutations

BACKGROUND

Pituitary adenomas (PA) associated with pheochromocytomas/paragangliomas (Pheo/PGL), also known as "the three P association" or "3PAs" could be the results of coincidence, but new evidence supports a common pathogenic mechanism in some patients. Our aim is to report the clinical data, surgical outcome, genetic findings of a large case series and review the current knowledge on this topic.

METHODS AND RESULTS

In a retrospective multicentre study, we compiled 10 patients with PAs (6 new unreported cases). Six patients were female with mean age of 51.6 ± 18.0 years. PA were: 6 acromegaly, 3 prolactinoma and 1 non-functioning PA (NFPA). Among the Pheo/PGL, 7 patients had a single tumour (4 Pheo and 3 PGL) and 3 patients had multiple or bilateral disease (2 PGL and 1 Pheo). Patients with GH-secreting PA and NFPA underwent surgery, while patients with prolactinoma received medical treatment (one patient required surgery). Unilateral adrenalectomy was carried out in all single Pheo and a bilateral procedure was performed in the patient with bilateral tumour. A single tumour was resected in two patients with multiple PGL. We found 3 germline pathogenic mutations: 2 in SDHB (c.166-170delCCTCA and a gross deletion involving exon 1) and 1 SDHD (p.P81L exon 3). Two variants of uncertain significance: 1 in MEN1 (c.1618C > T; p.Pro540Ser) and 1 in RET (c.2556C > G, p.Ile852Met), and finally a RET^M918T somatic mutation in a Pheo tissue.

CONCLUSION

We actively suggest considering the possibility of hereditary disease in all cases with 3PA and performing a complete genetic study.

The 3PAs: An Update on the Association of Pheochromocytomas, Paragangliomas, and Pituitary Tumors

Pituitary adenomas (PA) and pheochromocytomas/paragangliomas (PHEO/PGL) are rare tumors. Although they may co-exist by coincidence, there is mounting evidence that genes predisposing in PHEO/PGL development, may play a role in pituitary tumorigenesis. In 2012, we described a GH-secreting PA caused by an SDHD mutation in a patient with familial PGLs and found loss of heterozygosity at the SDHD locus in the pituitary tumor, along with increased hypoxia-inducible factor 1α (HIF-1α) levels. Additional patients with PAs and SDHx defects have since been reported. Overall, prevalence of SDHx mutations in PA is very rare (0.3-1.8% in unselected cases) but we and others have identified several cases of PAs with PHEOs/PGLs, like our original report, a condition which we termed the 3 P association (3PAs). Interestingly, when 3PAs is found in the sporadic setting, no SDHx defects were identified, whereas in familial PGLs, SDHx mutations were identified in 62.5-75% of the reported cases. Hence, pituitary surveillance is recommended among patients with SDHx defects. It is possible that the SDHx germline mutation-negative 3PAs cases may be due to another gene, epigenetic changes, mutations in modifier genes, mosaicism, somatic mutations, pituitary hyperplasia due to ectopic hypothalamic hormone secretion or a coincidence. PA in 3PAs are mainly macroadenomas, more aggressive, more resistant to somatostatin analogues, and often require surgery. Using the Sdhb +/- mouse model, we showed that hyperplasia may be the first abnormality in tumorigenesis as initial response to pseudohypoxia. We also propose surveillance and follow-up approach of patients presenting with this association.

Genetics of Cushing's Syndrome

The knowledge on the molecular and genetic causes of Cushing's syndrome (CS) has greatly increased in the recent years. Somatic mutations leading to overactive 3',5'-cyclic adenosine monophosphate/protein kinase A and wingless-type MMTV integration site family/beta-catenin pathways are the main molecular mechanisms underlying adrenocortical tumorigenesis. Corticotropinomas are characterized by resistance to glucocorticoid negative feedback, impaired cell cycle control and overexpression of pathways sustaining ACTH secretion. Recognizing the genetic defects behind corticotroph and adrenocortical tumorigenesis proves crucial for tailoring the clinical management of CS patients and for designing strategies for genetic counseling and clinical screening to be applied in routine medical practice.