SAT-LB302 From Urolithiasis to Genetic Testing: An Unusual Presentation of MEN-4 Syndrome

Background:Germline mutations in the CDKN1B gene are responsible for Multiple Endocrine Neoplasia Type 4 (MEN 4) syndrome (Alrezk et al. 2017). Around 20 cases have been reported to date. Here, we report on a new MEN4 family which possibly extends the phenotypic spectrum attributable to germline mutations in CDKN1B. Clinical Case: A 56-year-old female presented with urolithiasis & was found to have hypercalcemia (serum calcium of 2.76 mmol/l ref. 2.12-2.62 mmol/l). Workup was in keeping with primary hyperparathyroidism (PHPT) (PTH 28.7 pmol/l ref. 1.50-9.30 pmol/l; phosphorus 0.89 mmol/l ref. 0.80-1.45 mmol/l). Sestamibi & US of the neck revealed no clear parathyroid adenoma. Two incidental thyroid nodules were benign on FNA cytology. The patient underwent neck exploration & a single enlarged parathyroid gland was removed. Pathology showed an enlarged hypercellular gland. Her calcium & PTH normalized after surgery but recurrence was documented a year later. Her family history was significant for PHPT in two brothers & a history of kidney stones in a third brother. Multi-gene panel testing (CASR, CDC73, CDKN1B, MEN1, RET, Invitae Corp.) revealed a pathogenic variant (PV) in CDKN1B (c.215delG). The patient underwent a 2 ½ parathyroidectomy with subsequent normalization of her calcium & PTH. Further work-up showed a 4.5mm non-secreting pituitary adenoma. Plasma metanephrines & NE were intermittently elevated. Serum gastrin was also mildly elevated 83 pmol/l (<53 pmol/l). A Ga68-DOTATATE PET scan was negative. Her 23-year-old daughter tested positive for the familial PV. She is asymptomatic & has normal calcium & PTH; pituitary function is normal except for an elevated IGF-1 at 63.9 nmol/l (ref 13.3- 42.6 nmol/l) with borderline growth hormone during OGTT (0.40 ug/l). Her pituitary MRI was normal. One brother with history of prostate cancer, PHPT & partial parathyroidectomy has tested positive for the familial CDKN1B variant. A second brother was also found to carry the familial variant & was clinically asymptomatic.Endocrinological workup has revealed he has PHPT, elevated chromogranin A at 196.2 ng/ml (ref <=82), calcitonin at 25 ng/l (normal <=9 ng/l), IFG1 (35.3 nmol/L ref. 13-21) but normal plasma metanephrines. An MRI of the sella shows an 8mm hypoenhancing lesion. On CT, a retroperitoneal hyperenhancing 4cm mass adjacent to the left ilio-psoas was seen, in keeping with a paraganglioma; additionally, he has a congenital left atrophic kidney & ureter. Two additional brothers; one with history of non-Hodgkin’s lymphoma, PHPT & partial parathyroidectomy & a second brother, also with prostate cancer & recurrent renal stones, have yet to be tested. Conclusions: A new MEN4 family is described here which expands the spectrum of clinical manifestations of this syndrome. Of great interest in our cases is the presence of paraganglioma, urological malformation, & pre-clinical GH/IGF1 elevation.