Solène Castellnou, Alexandre Vasiljevic, Véronique Lapras, Véronique Raverot, Eudeline Alix, Françoise Borson-Chazot, Emmanuel Jouanneau, Gérald Raverot and Hélène Lasolle
Somatostatin receptor type 5 (SST5) is inconsistently expressed by corticotroph tumors, with higher expression found in corticotropinomas having ubiquitin-specific protease 8 (USP8) mutations. Aims were to study the correlation between characteristics of corticotropinomas and SST5 expression/USP8 mutation status and to describe the response to pasireotide in five patients.
Retrospective cohort study.
Clinico-biochemical, radiological and pathological data of 62 patients, operated for a functioning or silent corticotropinoma between 2013 and 2017, were collected. SST5 expression was measured by immunohistochemistry (clone UMB-4, Abcam, IRS > 1 being considered positive), and Sanger sequencing was performed on 50 tumors to screen for USP8 mutations.
SST5 expression was positive in 26/62 pituitary tumors. A moderate or strong IRS was found in 15/58 corticotropinomas and in 13/35 functioning corticotropinomas. Among functioning tumors, those expressing SST5 were more frequent in women (22/24 vs 9/15, P = 0.04) and had a lower grade (P = 0.04) compared to others. USP8 mutations were identified in 13/50 pituitary tumors and were more frequent in functioning compared to silent tumors (11/30 vs 2/20, P = 0.05). SST5 expression was more frequent in USP8mut vs USP8wt tumors (10/11 vs 7/19, P = 0.007). Among treated patients, normal urinary free cortisol levels were obtained in three patients (IRS 0, 2 and 6), while a four-fold decrease was observed in one patient (IRS 4).
SST5 expression appears to be associated with functioning, USP8mut and lower grade corticotropinomas. A correlation between SST5 expression or USP8mut and response to pasireotide remains to be confirmed.
Louise Vølund Larsen, Delphine Mirebeau-Prunier, Tsuneo Imai, Cristina Alvarez-Escola, Kornelia Hasse-Lazar, Simona Censi, Luciana A Castroneves, Akihiro Sakurai, Minoru Kihara, Kiyomi Horiuchi, Véronique Dorine Barbu, Francoise Borson-Chazot, Anne-Paule Gimenez-Roqueplo, Pascal Pigny, Stephane Pinson, Nelson Wohllk, Charis Eng, Berna Imge Aydogan, Dhananjaya Saranath, Sarka Dvorakova, Frederic Castinetti, Attila Patocs, Damijan Bergant, Thera P Links, Mariola Peczkowska, Ana O Hoff, Caterina Mian, Trisha Dwight, Barbara Jarzab, Hartmut P H Neumann, Mercedes Robledo, Shinya Uchino, Anne Barlier, Christian Godballe and Jes Sloth Mathiesen
Multiple endocrine neoplasia type 2A (MEN 2A) is a rare syndrome caused by RET germline mutations and has been associated with primary hyperparathyroidism (PHPT) in up to 30% of cases. Recommendations on RET screening in patients with apparently sporadic PHPT are unclear. We aimed to estimate the prevalence of cases presenting with PHPT as first manifestation among MEN 2A index cases and to characterize the former cases.
Design and methods
An international retrospective multicenter study of 1085 MEN 2A index cases. Experts from MEN 2 centers all over the world were invited to participate. A total of 19 centers in 17 different countries provided registry data of index cases followed from 1974 to 2017.
Ten cases presented with PHPT as their first manifestation of MEN 2A, yielding a prevalence of 0.9% (95% CI: 0.4–1.6). 9/10 cases were diagnosed with medullary thyroid carcinoma (MTC) in relation to parathyroid surgery and 1/10 was diagnosed 15 years after parathyroid surgery. 7/9 cases with full TNM data were node-positive at MTC diagnosis.
Our data suggest that the prevalence of MEN 2A index cases that present with PHPT as their first manifestation is very low. The majority of index cases presenting with PHPT as first manifestation have synchronous MTC and are often node-positive. Thus, our observations suggest that not performing RET mutation analysis in patients with apparently sporadic PHPT would result in an extremely low false-negative rate, if no other MEN 2A component, specifically MTC, are found during work-up or resection of PHPT.