Session: FP35-Neoplasia of Endocrine Tissues
Bench to Bedside
Room 122 (Moscone Center)
Poster Board MON-295
Methods: Data from 16 patients with MEN 2B and MTC were analyzed, 9 F, median age 13.3 years (9.1-17.3). 2 patients had unilateral adrenalectomy performed prior to initiating VD. MN levels were followed for a median of 35 mo. (1-51). 15 pts underwent 2 adrenal CTs a mean of 2.2 ± 0.8 years apart (2mm slice thickness, w/IV contrast). These were reviewed by a single radiologist blinded to MN level. Data are reported as median (range), and were compared using paired tests.
Results: Baseline MN level was 55 pg/mL (32-179); 33% were above the ULN of 61. Over the course of the entire study, 87% of patients had at least 1 elevated MN level, with a median peak level of 0.41 x the ULN, (-0.3-2.9). Individual MN levels were more likely to be elevated at any other point over the course of the study compared to baseline (p=0.005). However, in the 10 patients followed for 2-3 y, MN levels remained stable compared to baseline at 59 pg/mL (33-143; p=0.54). None of the adrenal CTs showed enhancing lesions typical of obvious PHEO. 3 patients had possible non-enhancing focal lesions, while 3 patients had adrenal hyperplasia (max. thickness of either the adrenal body or limb of ≥6 mm).
Conclusions: 87% of pediatric MEN2B pts had elevated MN levels at some point over the course of the study; 38% were found to have possible adenoma or hyperplasia on adrenal CT. However, MN levels remained stably elevated; in the absence of controls it is impossible to sort out VD effect vs. natural history of MEN2B. Patients with true PHEO must undergo proper adrenergic blockade to avoid paroxysmal attacks, yet it remains unclear at what point to intervene when the patient has medullary hyperplasia and levels of MN < 3 times ULN. TKIs against RET may be effective in stabilizing medullary hyperplasia, these agents are being further evaluated in this context.
Nothing to Disclose: MBL, NS, AL, AS, KP, BW, CAS
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