Aggressive and Malignant Prolactinomas.

Prolactin-secreting tumors (prolactinomas) represent the most common pituitary tumor type, accounting for 47-66% of functional pituitary tumors. Prolactinomas are usually benign and controllable tumors as they express abundant levels of dopamine type 2 receptor (D2), and can be treated with dopaminergic drugs, effectively reducing prolactin levels and tumor volume. However, a proportion of prolactinomas exhibit aggressive features (including invasiveness, relevant growth despite adequate dopamine agonist treatment, and recurrence potential) and few may exhibit metastasizing potential (carcinomas). In this context, the clinical, pathological, and molecular definitions of malignant and aggressive prolactinomas remain to be clearly defined, as primary prolactin-secreting carcinomas are similar to aggressive adenomas until the presence of metastases is detected. Indeed, standard molecular and histological analyses do not reflect differences between carcinomas and adenomas at a first glance and have limitations in prediction of the aggressive progression of prolactinomas, wherein the causes underlying the aggressive behavior remain unknown. Herein we present a comprehensive, multidisciplinary review of the most relevant epidemiological, clinical, pathological, genetic, biochemical, and molecular aspects of aggressive and malignant prolactinomas.

Inhibition of Heat Shock Factor 1 Enhances Repressive Molecular Mechanisms on the POMC Promoter.

BACKGROUND: Cushing's disease (CD) is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary tumours. They express high levels of heat shock protein 90 and heat shock factor 1 (HSF1) in comparison to the normal tissue counterpart, indicating activated cellular stress. AIMS: Our objectives were: (1) to correlate HSF1 expression with clinical features and hormonal/radiological findings of CD, and (2) to investigate the effects of HSF1 inhibition as a target for CD treatment. PATIENTS/METHODS: We examined the expression of total and pSer326HSF1 (marker for its transcriptional activation) by Western blot on eight human CD tumours and compared to the HSF1 status of normal pituitary. We screened a cohort of 45 patients with CD for HSF1 by immunohistochemistry and correlated the HSF1 immunoreactivity score with the available clinical data. We evaluated the effects of HSF1 silencing with RNA interference and the HSF1 inhibitor KRIBB11 in AtT-20 cells and four primary cultures of human corticotroph tumours. RESULTS: We show that HSF1 protein is highly expressed and transcriptionally active in CD tumours in comparison to normal pituitary. The immunoreactivity score for HSF1 did not correlate with the typical clinical features of the disease. HSF1 inhibition reduced proopiomelanocortin (Pomc) transcription in AtT-20 cells. The HSF1 inhibitor KRIBB11 suppressed ACTH synthesis from 75% of human CD tumours in primary cell culture. This inhibitory action on Pomc transcription was mediated by increased glucocorticoid receptor and suppressed Nurr77/Nurr1 and AP-1 transcriptional activities. CONCLUSIONS: These data show that HSF1 regulates POMC transcription. Pharmacological targeting of HSF1 may be a promising treatment option for the control of excess ACTH secretion in CD.

TP53 mutations in functional corticotroph tumors are linked to invasion and worse clinical outcome.

Corticotroph macroadenomas are rare but difficult to manage intracranial neoplasms. Mutations in the two Cushing's disease mutational hotspots USP8 and USP48 are less frequent in corticotroph macroadenomas and invasive tumors. There is evidence that TP53 mutations are not as rare as previously thought in these tumors. The aim of this study was to determine the prevalence of TP53 mutations in corticotroph tumors, with emphasis on macroadenomas, and their possible association with clinical and tumor characteristics. To this end, the entire TP53 coding region was sequenced in 86 functional corticotroph tumors (61 USP8 wild type; 66 macroadenomas) and the clinical characteristics of patients with TP53 mutant tumors were compared with TP53/USP8 wild type and USP8 mutant tumors. We found pathogenic TP53 variants in 9 corticotroph tumors (all macroadenomas and USP8 wild type). TP53 mutant tumors represented 14% of all functional corticotroph macroadenomas and 24% of all invasive tumors, were significantly larger and invasive, and had higher Ki67 indices and Knosp grades compared to wild type tumors. Patients with TP53 mutant tumors had undergone more therapeutic interventions, including radiation and bilateral adrenalectomy. In conclusion, pathogenic TP53 variants are more frequent than expected, representing a relevant amount of functional corticotroph macroadenomas and invasive tumors. TP53 mutations associated with more aggressive tumor features and difficult to manage disease.

Tumor ZAC1 expression is associated with the response to somatostatin analog therapy in patients with acromegaly.

Somatostatin analogs (SSA) with their potent antisecretory and antiproliferative effects are the main medical treatment option for patients with neuroendocrine tumors, such as gastroenteropancreatic and acromegaly-associated growth hormone secreting pituitary tumors. Although a good portion of acromegalic patients gets normalized after SSA treatment, strict hormonal control is not achieved in a sizeable proportion of these patients. The reasons for this incomplete response to SSA treatment are unclear. We have found that the tumor suppressor ZAC1 (LOT1/PLAGL1) is essential for the antiproliferative effect of SSA in pituitary tumor cells. The aim of the present retrospective cohort study was to determine whether ZAC1 immunoreactivity in archival somatotrophinoma tissue derived from 45 patients with acromegaly routinely pretreated with SSA before surgery, was associated with response to SSA (normalization of GH, IGF-I and presence of tumor shrinkage). All tumors displayed ZAC1 immunoreactivity [weak (+; n = 15), moderate (++; n = 16) and strong (+++; n = 14)]. A significant positive correlation was found between strong ZAC1 immunoreactivity and IGF-I normalization and presence of tumor shrinkage after SSA treatment, which was not affected by age at diagnosis, gender or duration of SSA treatment. These in vivo data combined with the antiproliferative properties of ZAC1/Zac1 provide evidence of a mechanistic role for this transcription factor on SSA induced tumor shrinkage and hormone normalization.

Genetic, molecular and clinical features of familial isolated pituitary adenomas.

Pituitary adenomas occur in a familial setting in about 5% of all cases, and over half of these are due to multiple endocrine neoplasia type 1 (MEN1) and Carney's complex (CNC). Non-MEN1/CNC familial pituitary tumours of all tumour phenotypes, known as familial isolated pituitary adenomas (FIPA), were first described in the late 1990s. Clinical features of FIPA differ from those of sporadic pituitary adenomas, as patients with FIPA have a younger age at diagnosis and larger tumours. About 15% of patients with FIPA have mutations in the aryl hydrocarbon receptor-interacting protein gene (AIP), which indicates that FIPA may have a diverse genetic pathophysiology. This article describes the clinical features of FIPA, the tumour pathologies found in this setting and the genetic/molecular data that have recently been reported in FIPA.

Update on familial pituitary tumors: from multiple endocrine neoplasia type 1 to familial isolated pituitary adenoma.

BACKGROUND: Pituitary adenomas occur in a familial setting in about 5% of all cases and over half of these are due to multiple endocrine neoplasia type 1 (MEN1) and Carney complex (CNC). Since the late 1990s, we have described non-MEN1/CNC familial pituitary tumors that include all tumor phenotypes and have named this condition 'familial isolated pituitary adenoma' (FIPA). Clinical features of FIPA differ from those of sporadic pituitary adenomas in that patients with FIPA are often younger and have larger tumors at diagnosis. About 15% of FIPA patients have mutations in the aryl hydrocarbon receptor interacting protein gene (AIP), which indicates that FIPA may have a diverse genetic pathophysiology. We review the clinical features of FIPA, the tumor pathologies found in this setting and the genetic/molecular data that have been recently reported. CONCLUSIONS: Clinically relevant pituitary adenomas are more common than previously thought and occur in a familial setting in about 5% of cases overall. Therefore, specific questioning regarding family history of pituitary disease should be part of the workup of all patients with pituitary adenomas, not just those with acromegaly. FIPA is a useful clinical framework to study the features of pituitary adenomas that occur in a familial setting since it encompasses all tumor phenotypes and heterogeneous/homogeneous expression among affected family members.

[AIP mutations in familial and sporadic pituitary adenomas: local experience and review of the literature]. / Mutaciones de AIP en adenomas hipofisarios familiares y esporádicos: experiencia local y revisión de la literatura.

Clinically relevant pituitary adenomas occur 3-5 times more frequently than previously thought. The majority are isolated cases, but their presentation can be familial in the setting of known syndromes such as multiple endocrine neoplasia (MEN)-1 and Carney complex. When 2 or more cases of pituitary adenomas occur in the same family in the absence of the above-mentioned syndromes, a diagnosis of FIPA (familial isolated pituitary adenomas) is made, which accounts for 1-2% of all pituitary adenomas. Mutations of the gene AIP (aryl hydrocarbon receptor-interacting protein) may account for 15% of FIPA families (50% of familial acromegaly), and as such the genetic causes continue to be studied. Also mutations in AIP can be detected in sporadic adenomas among young populations (< 30 years of age). We describe the characteristics of FIPA, detailing the study of a spanish family, in this case AIP mutation negative. Also, the reported findings in sporadic adenomas in the young population are detailed, accompanied by the description of a 19- year old patient with an intronic AIP mutation. Multicenter studies have provided understanding of aspects such as mutations in AIP; however, further studies are necessary to identify other genes involved in FIPA and sporadic pituitary adenomas occurring at a young age.

Toll-like receptor-4 is expressed in meningiomas and mediates the antiproliferative action of paclitaxel.

Meningiomas are the second most common type of brain and CNS tumors by histology. Surgery and radiotherapy are main treatment options, but meningiomas may be impossible to adequately resect or may regrow after surgery. In spite of many experimental attempts, there is no generally accepted chemotherapeutic approach. We have studied in a series of meningiomas the expression of the Toll-like receptor 4 (TLR4), which apart from its major role as a key factor of the innate immune system, is believed to play a role in tumorigenesis. All meningiomas studied expressed TLR4 mRNA and protein at variable degree. Paclitaxel, a ligand of TLR4, exhibited a dose- and time-dependent growth suppression in both monolayer and spheroid meningioma cell cultures. The knockdown of TLR4 with siRNA in meningioma cell cultures abrogated the inhibitory effect of paclitaxel. The suppressive action of paclitaxel on meningioma cell growth was enhanced in the presence of fluvastatin or the mitogen-actvated protein kinase (ERK1/2) inhibitor PD98059. At least part of the growth suppressive effect was mediated by the induction of apoptosis in meningioma cells by paclitaxel alone or in combination with fluvastatin. In conclusion, our in vitro results suggest that paclitaxel alone or in combination with other inhibitors of cell growth (statins, MAPK inhibitors) could provide a potential tool for the treatment of TLR4 expressing meningiomas.

High prevalence of pituitary adenomas: a cross-sectional study in the province of Liege, Belgium.

CONTEXT: Prevalence data are important for assessing the burden of disease on the health care system; data on pituitary adenoma prevalence are very scarce. OBJECTIVE: The objective of the study was to measure the prevalence of clinically relevant pituitary adenomas in a well-defined population. DESIGN: This was a cross-sectional, intensive, case-finding study performed in three regions of the province of Liège, Belgium, to measure pituitary adenoma prevalence as of September 30, 2005. SETTING: The study was conducted in specialist and general medical practitioner patient populations, referral hospitals, and investigational centers. METHODS: Three demographically and geographically distinct districts of the province of Liège were delineated precisely using postal codes. Medical practitioners in these districts were recruited, and patients with pituitary adenomas under their care were identified. Diagnoses were confirmed after retrieval of clinical, hormonal, radiological, and pathological data; full demographic and therapeutic follow-up data were collected in all cases. RESULTS: Sixty-eight patients with clinically relevant pituitary adenomas were identified in a population of 71,972 individuals; the mean (+/- sd) prevalence was 94 +/- 19.3 cases per 100,000 population (95% confidence interval, 72.2 to 115.8). The group was 67.6% female and had a mean age at diagnosis of 40.3 yr; 42.6% had macroadenomas and 55.9% underwent surgery. Prolactinomas comprised 66% of the group, with the rest having nonsecreting tumors (14.7%), somatotropinomas (13.2%), or Cushing's disease (5.9%); 20.6% had hypopituitarism. CONCLUSION: The prevalence of pituitary adenomas in the study population (one case in 1064 individuals) was more than 3.5-5 times that previously reported. This increased prevalence may have important implications when prioritizing funding for research and treatment of pituitary adenomas.

The role of poly (adenosine 5'-diphosphate-ribose) polymerase in the response of pituitary tumor cells to reactive oxygen species.

As an enzyme implicated in the stress response, we investigated poly(ADP-ribose) polymerase (PARP) in the response of GH3 rat pituitary tumor cells to oxidants. These cells are unusual in that they undergo rapid cell death (90 min) with low doses of the prooxidant, H2O2 (50-200 microm), whereas at higher doses (1 mm), death occurs some hours later (4-5 h). Measurement of PARP activity shows that low doses of H2O2 (50-200 microm) fail to increase the activity of PARP, whereas at 0.5 and 1 mm, the enzyme becomes activated. In parallel with the activation of PARP, cellular ATP concentrations fall at high H2O2 doses and the PARP inhibitors, 3-aminobenzamide and nicotinamide (NIC) partially prevent this fall. Using NIC to inhibit PARP activity, we show that treatment of cells with NIC before the addition of H2O2 (0.5-1 mm), results in rapid cell death (90 min). In contrast, prior exposure to H2O2 (0.5-1 mm) for 1 h, before withdrawal and exposure to 1 mm NIC, allows cell survival for many hours. These data suggest that PARP is involved in blocking rapid death of GH3 cells in response to oxidants. In contrast to other cell types tested here, in which inhibitor studies show that PARP is activated at low H2O2 doses and this decreases the extent of apoptosis, GH3 cells are unable to sufficiently activate PARP to prevent rapid cell death.

Functional in vitro studies on the role and regulation of interleukin-6 in human somatotroph pituitary adenomas.

OBJECTIVE: Interleukin-6 (IL-6), a member of the gp130 cytokine family, is considered to be an important modulator of function and growth in endocrine anterior pituitary cells. In pituitary adenomas, where IL-6 is often produced by the tumour cells, it is thought to be involved in pituitary adenoma pathophysiology via autocrine/paracrine mechanisms. METHODS: We have studied in primary cell cultures of human somatotroph adenomas whether IL-6 stimulates growth hormone secretion and whether intratumoral IL-6 is affected by various IL-6-regulating factors. RESULTS: Interleukin-6 stimulated GH secretion in 10 out of 11 somatotroph adenoma cultures (1.4- to 6.5-fold above basal levels). In comparative studies the GH-stimulatory potency of IL-6 was identical, or even stronger, than that of GHRH. In eight out of 11 adenoma cell cultures, IL-6 production was observed. This suggests that GH production might be stimulated by IL-6 in an autocrine/paracrine manner in these tumours. Dexamethasone strongly inhibited basal IL-6 secretion in all IL-6-producing adenoma cell cultures, whereas the IL-6 inhibitory or stimulatory action of other factors (octreotide, transforming growth factor-beta1, insulin-like growth factor-I, pituitary adenylate cyclase-activating peptide and oestradiol) were heterogeneous in the different adenomas. Only transforming growth factor-alpha consistently stimulated IL-6 secretion in all of the adenomas studied. CONCLUSIONS: Intratumoral IL-6, which is differently regulated by various factors, might contribute to excessive GH production in the majority of somatotroph adenomas.

The Liege Acromegaly Survey (LAS): a new software tool for the study of acromegaly.

Acromegaly is a chronic rare disease associated with negative pathological effects on multiple systems and organs. We designed a new informatics tool to study data from patients with acromegaly, the Liege Acromegaly Survey (LAS). This relational database permits the inclusion of anonymous historical and prospective data on patients and includes pathophysiology, clinical features, responses to therapy and long term outcomes of acromegaly. We deployed the LAS in a validation study at a single center in order to study the characteristics of patients with acromegaly diagnosed at our center from 1970-2011. A total of 290 patients with acromegaly were included (147 males and 143 females). There was a linear relationship between age at diagnosis and the date of diagnosis, indicating that older patients are being diagnosed with acromegaly more frequently. A majority presented with macroadenomas (77.5%) and the median diameter was 14 mm. Patients with macroadenomas were significantly younger than patients with microadenomas (P=0.01). GH values at diagnosis decreased with the age of the patients (P=0.01) and there was a correlation between GH values and tumor size at diagnosis (P=0.02). No correlation existed between insulin-like growth factor 1 (IGF-1) levels and tumor characteristics. The prevalence of diabetes was 21.4% in this population and 41.0% had hypertension. The presence of hypertension and diabetes were significantly associated with one another (P<0.001). There was a linear relation between initial GH and IGF-1 levels at diagnosis and those obtained during SSA analog treatment and the lowest GH and IGF-1 values following SSA therapy were obtained in older patients (GH: P<0.001; IGF-1: P<0.001). The LAS is a new relational database that is feasible to use in the clinical research setting and permits ready pooling of anonymous patient data from multiple study sites to undertake robust statistical analyses of clinical and therapeutic characteristics.

Cyclin-dependent kinase inhibitor 1B (CDKN1B) gene variants in AIP mutation-negative familial isolated pituitary adenoma kindreds.

Familial isolated pituitary adenoma (FIPA) occurs in families and is unrelated to multiple endocrine neoplasia type 1 and Carney complex. Mutations in AIP account only for 15-25% of FIPA families. CDKN1B mutations cause MEN4 in which affected patients can suffer from pituitary adenomas. With this study, we wanted to assess whether mutations in CDKN1B occur among a large cohort of AIP mutation-negative FIPA kindreds. Eighty-eight AIP mutation-negative FIPA families were studied and 124 affected subjects underwent sequencing of CDKN1B. Functional analysis of putative CDKN1B mutations was performed using in silico and in vitro approaches. Germline CDKN1B analysis revealed two nucleotide changes: c.286A>C (p.K96Q) and c.356T>C (p.I119T). In vitro, the K96Q change decreased p27 affinity for Grb2 but did not segregate with pituitary adenoma in the FIPA kindred. The I119T substitution occurred in a female patient with acromegaly. p27(I119T) shows an abnormal migration pattern by SDS-PAGE. Three variants (p.S56T, p.T142T, and c.605+36C>T) are likely nonpathogenic because In vitro effects were not seen. In conclusion, two patients had germline sequence changes in CDKN1B, which led to functional alterations in the encoded p27 proteins in vitro. Such rare CDKN1B variants may contribute to the development of pituitary adenomas, but their low incidence and lack of clear segregation with affected patients make CDKN1B sequencing unlikely to be of use in routine genetic investigation of FIPA kindreds. However, further characterization of the role of CDKN1B in pituitary tumorigenesis in these and other cases could help clarify the clinicopathological profile of MEN4.

High prevalence of AIP gene mutations following focused screening in young patients with sporadic pituitary macroadenomas.

BACKGROUND: Aryl hydrocarbon receptor interacting protein (AIP) mutations (AIPmut) cause aggressive pituitary adenomas in young patients, usually in the setting of familial isolated pituitary adenomas. The prevalence of AIPmut among sporadic pituitary adenoma patients appears to be low; studies have not addressed prevalence in the most clinically relevant population. Hence, we undertook an international, multicenter, prospective genetic, and clinical analysis at 21 tertiary referral endocrine departments. METHODS: We included 163 sporadic pituitary macroadenoma patients irrespective of clinical phenotype diagnosed at <30 years of age. RESULTS: Overall, 19/163 (11.7%) patients had germline AIPmut; a further nine patients had sequence changes of uncertain significance or polymorphisms. AIPmut were identified in 8/39 (20.5%) pediatric patients. Ten AIPmut were identified in 11/83 (13.3%) sporadic somatotropinoma patients, in 7/61 (11.5%) prolactinoma patients, and in 1/16 non-functioning pituitary adenoma patients. Large genetic deletions were not seen using multiplex ligation-dependent probe amplification. Familial screening was possible in the relatives of seven patients with AIPmut and carriers were found in six of the seven families. In total, pituitary adenomas were diagnosed in 2/21 AIPmut-screened carriers; both had asymptomatic microadenomas. CONCLUSION: Germline AIPmut occur in 11.7% of patients <30 years with sporadic pituitary macroadenomas and in 20.5% of pediatric patients. AIPmut mutation testing in this population should be considered in order to optimize clinical genetic investigation and management.

Genetic factors in the development of pituitary adenomas.

Pituitary adenomas are one of the most frequent intracranial tumors. Usually, they are benign but are of great clinical significance because of tumor compression syndrome and hormone overproduction. The interest in this pathology is increasing, particularly after some recent reports on their prevalence that proved to be 3-5 times more than previously estimated. Pituitary tumors arise in a sporadic setting and rarely as part of hereditary genetic syndromes. Such rare hereditary conditions like MEN1, Carney complex and McCune-Albright syndrome give significant insight into pituitary tumorigenesis. Newer genes associated pituitary tumor development include CDKN1B (MEN4) and AIP, the latter of which is involved in the pathophysiology of 15% of FIPA kindreds. The number of genes involved in pituitary tumorigenesis is progressively increasing and the possible mechanisms of action include signal transduction pathways, cell cycle regulators, growth factors, chromosome instability and others. Nevertheless, in the majority of sporadic adenomas, the primary genetic defect remains unknown. Furthermore, there is not a well established relationship between the genotype and its influence on the protein expression, ligand-receptor interaction, tumor growth or hormone hyperproduction. Further studies should evaluate the clinical significance of genetic alterations and their implications for existing and new therapeutic options.

The genetics of pituitary adenomas.

Pituitary adenomas are one of the most frequent intracranial tumors with a prevalence of clinically-apparent tumors close to 1:1000 of the general population. They are clinically significant because of hormone overproduction and/or tumor mass effects in addition to the need for neurosurgery, medical therapies and radiotherapy. The majority of pituitary adenomas have a sporadic origin with recognized genetic mutations seldom being found; somatotropinomas are an exception, presenting frequent somatic GNAS mutations. In this and other phenotypes, tumorigenesis could possibly be explained by altered function of genes implicated in cell cycle regulation, growth factors or their receptors, cell-signaling pathways, specific hormonal factors or other molecules with still unclear mechanisms of action. Genetic changes, such as allelic loss or gene amplification, and epigenetic changes, usually by promoter methylation, have been implicated in abnormal gene expression, but alternative mechanisms may be present. Familial cases of pituitary adenomas represent 5% of all pituitary tumors. MEN1 mutations cause multiple endocrine neoplasia type 1 (MEN1), while the Carney complex (CNC) is characterized by mutations in the protein kinase A regulatory subunit-1alpha (PRKAR1A) gene or changes in a locus at 2p16. Recently, a MEN1-like condition, MEN4, was found to be related to mutations in the CDKN1B gene. The clinical entity of familial isolated pituitary adenomas (FIPA) is characterized by genetic defects in the aryl hydrocarbon receptor interacting protein (AIP) gene in about 15% of all kindreds and 50% of homogenous somatotropinoma families. Identification of familial cases of pituitary adenomas is important as these tumors may be more aggressive than their sporadic counterparts.

Clinical characteristics and therapeutic responses in patients with germ-line AIP mutations and pituitary adenomas: an international collaborative study.

CONTEXT: AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. OBJECTIVE: The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. DESIGN: This study was an international, multicenter, retrospective case collection/database analysis. SETTING: The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. PATIENTS: Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. RESULTS: The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n = 13), nonsecreting adenomas (n = 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P = 0.00026), with higher GH levels (P = 0.00068), more frequent extension (P = 0.018) and prolactin cosecretion (P = 0.00023), and occurred 2 decades before controls (P < 0.000001). Gigantism was more common in the AIPmut group (P < 0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P = 0.00069) and had lower decreases in GH (P = 0.00037) and IGF-I (P = 0.028) and less tumor shrinkage with somatostatin analogs (P < 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. CONCLUSIONS: AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility.

The epidemiology and genetics of pituitary adenomas.

According to data derived from autopsy and radiological imaging series, pituitary tumours occur very commonly in the general population; however, most of these tumours are incidental findings with no obvious clinical impact. The historical data on the prevalence of pituitary adenomas in the clinical setting are scant and point to such tumours being relatively rare. Recent studies have shown that the prevalence of clinically relevant pituitary adenomas is 3-5 times higher than previously reported, which adds impetus to research into the aetiology of these tumours. Although the majority of pituitary adenomas are sporadic, approximately 5% of all cases occur in a familial setting and over half of these are due to Multiple Endocrine Neoplasia Type 1 (MEN-1) and Carney's Complex (CNC) disorders. Since the late 1990 s, we have described non-MEN1/CNC familial pituitary tumours that include all tumour phenotypes as a condition termed Familial Isolated Pituitary Adenomas (FIPAs). The clinical characteristics of the FIPAs vary from those sporadic pituitary adenomas, as patients with FIPAs have a younger age at diagnosis and larger tumours. About 15% of the FIPA patients have mutations in the aryl hydrocarbon receptor-interacting protein gene (AIP), which indicates that the FIPA may have a diverse genetic pathophysiology.

[Familial pituitary adenomas]. / Adénomes hypophysaires familiaux.

Familial pituitary adenomas are found in multitumoral syndromes such as multiple endocrine neoplasia type 1 (NEM1) and type 4 (NEM4) and the Carney complex (CNC); it remains at present the only known condition in the category of familial isolated pituitary adenomas (FIPA). Familial adenomas account for 3-5% of all pituitary adenomas. Their pathogenesis is known in part: mutations of the menin gene in NEM1 (80%), of the CDKN1B gene in NEM4 (several cases described), of the PRKR1A gene in CNC (50%) and the AIP gene in 15% of FIPA cases (50% of the FIPA cases with a homogeneous somatotropic phenotype). The clinical course of familial adenoma with NEM1 or FIPA is more aggressive than that of sporadic adenoma, with more macroadenomas and more patients diagnosed younger. Familial pituitary adenomas are distinguished from the sporadic forms in their genetic, epidemiologic and clinical characteristics. They require a differentiated management, especially concerning screening.

Aggressive pituitary adenomas occurring in young patients in a large Polynesian kindred with a germline R271W mutation in the AIP gene.

OBJECTIVE: Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) were recently shown to confer a pituitary adenoma predisposition in patients with familial isolated pituitary adenomas (FIPA). We report a large Samoan FIPA kindred from Australia/New Zealand with an R271W mutation that was associated with aggressive pituitary tumors. DESIGN AND METHODS: Case series with germline screening of AIP and haplotype analyses among R271W families. RESULTS: This previously unreported kindred consisted of three affected individuals that either presented with or had first symptoms of a pituitary macroadenoma in late childhood or adolescence. The index case, a 15-year-old male with incipient gigantism and his maternal aunt, had somatotropinomas, and the maternal uncle of the index case had a prolactinoma. All tumors were large (15, 40, and 60 mm maximum diameter) and two required transcranial surgery and radiotherapy. All three affected subjects and ten other unaffected relatives were found to be positive for a germline R271W AIP mutation. Comparison of the single nucleotide polymorphism patterns among this family and two previously reported European FIPA families with the same R271W mutation demonstrated no common ancestry. CONCLUSIONS: This kindred exemplifies the aggressive features of pituitary adenomas associated with AIP mutations, while genetic analyses among three R271W FIPA families indicate that R271W represents a mutational hotspot that should be studied further in functional studies.