Pancreas-related results
Islet cell tumors are the most common endocrine gland tumor in MEN1. Several symptoms (large appetite and rapid hungering, intermittent recurrent fatigue, palpitations, and sweating) in the proband suggested that pancreatic insulinoma had greater likelihood. In addition, during hospitalization, the proband experienced hypoglycemia symptoms twice. Meanwhile, the proband’s serum glucose, insulin (INI), C-peptide (CPS), and pro-insulin (pro-INS) levels were tested, and the results showed that glucose was decreased while the insulin level was either in the normal reference range or increased at the time of the hypoglycemia (Table 1). The insulin release indexes were 0.55 and 0.52 (normal range <0.3) during the twice hypoglycemia, respectively. A prolonged oral glucose tolerance test (OGTT) was performed, and the results presented hypoglycemia at the 240th and 300th minute with glucose levels of 2.01 mmol/L and 1.95 mmol/L, respectively. The corresponding insulin release indexes were 0.48 and 0.43, respectively (Table 2).
The imaging examinations provided us with more information. The CT results of the pancreas showed that the mass in the pancreatic neck (8.0 x 6.8 x 8.4 cm) could have been a solid pseudopapillary tumor (Fig. 1a1–a4). Circular reinforced nodules in the tail of the pancreas (2.8 x 2.7 cm) (Fig. 1b1–b4) were considered to be homologous with the pancreatic neck mass (solid pseudopapillary tumor). The arterial phase of the pancreatic tail artery significantly strengthened the small nodules at the early stage, which could have been a neuroendocrine tumor. EUS is considered to be the most sensitive single method for the detection of pancreatoduodenal tumors. Compared with a CT scan and somatostatin receptor imaging, EUS has obvious advantages (8). The patient’s ultrasound gastroscopy showed that the head of the pancreas could not be observed in the full field because the mass was too big (Fig. 1c1–c2). The mass in the tail of the pancreas (2.81 x 2.02 cm) (Fig. 1c3–c4) was a hypoechoic mass, and the internal echoes were mixed.
Therefore, the mass in the pancreas was likely an islet cell tumor. Later on, we checked other endocrine glands of the proband.
Parathyroid-related results
In MEN1 patients, the prevalence of parathyroid tumors is about 95% (7). The proband’s serum tests showed that the serum calcium (Ca2+) was increased (2.47–2.74 mmol/L, normal range 2.17–2.57 mmol/L) and serum phosphorus (P) was decreased (0.71–0.96 mmol/L, normal range 0.81–1.52 mmol/L). The serum parathyroid hormone was 553.6 pg/mL (normal range 15–65 pg/mL).
The results of the patient’s bone mineral density measurements presented a decrease in bone mass in the lumbar spine and hip joint bones. Imaging modalities, such as parathyroid ultrasound and ECT, are valuable in MEN1 patients (9). Parathyroid ultrasound showed a low echo at the posterior margin of the thyroid (right, 7.9 x 4.5 mm; left, 11.0 x 3.6 mm). Fifteen minutes after the 99mTc-stabimidine (MIBI) injection, the parathyroid ECT demonstrated an area of increased imaging agent in the lower lobe of the left thyroid (Fig. 1d1, d3). Two hours after the injection, the imaging agent that was increased in the left lobe of the thyroid had not significantly decreased (Fig. 1d2, d4). This phenomenon was caused by a highly functional parathyroid adenoma.
The above results confirmed that the proband had primary hyperparathyroidism that could derive from the highly functional parathyroid adenoma.
Adrenal gland-related results
Asymptomatic adrenal tumors occur in about 20% to 73% of MEN1 patients. Patients with MEN1 tend to develop aldosterone and adrenocortical cancer but are less likely to develop pheochromocytoma than those with adrenal incidentaloma (10). The proband’s CT result showed that a mass occupied the right adrenal gland (Fig. 1e).
The biochemical evaluation of adrenal tumors includes an evaluation of plasma free cortisone (COR), evening cortisol, plasma renin, and aldosterone concentration, and a 1-mg overnight dexamethasone (DXM) suppression test (9). In this case, the basal COR rhythm was turbulent. The 1-mg overnight DXM suppression test results demonstrated that the inhibition rate of COR was 76.4% (normal range >50%). Therefore, Cushing syndrome was excluded. The plasma renin and aldosterone concentrations were normal. Moreover, the patient did not have hypertension.
All of these findings suggested that a nonfunctional adrenal tumor existed.
Pituitary-related results
The serum prolactin (PRL) was two times the normal upper limit (1253 mIU/L, normal range 40–530 mIU/L; rechecked 1395 mIU/L). Serial basal PRL levels greater than 4240 mIU/L confirmed a prolactinoma (9). The results of the metoclopramide stimulation test showed that PRL was 1.88 times higher than the basic value and the inhibition rate of PRL was 60.7% (normal range > 50%), as found by the bromocriptine inhibition test. This indicated that the patient suffered from a prolactinoma of the pituitary. Other pituitary hormones, including growth hormone (GH), IGF-1 (insulin-like growth factor 1), luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and free-thyroxine (FT4), were normal.
An MRI of the pituitary gland with contrast is the best diagnostic imaging (9). The pituitary-enhanced MRI examination showed that the hypophysis was full in shape (height 0.95 cm) (Fig. 1f1–f3). Based on the above serum and imaging examination, the proband could have had a prolactinoma. The small size of the pituitary tumor could have led to the inconspicuous imaging evidence.
Stomach and duodenum-related tumor
The incidence of neuroendocrine tumors (NETs) in gastrointestinal and pancreatic tissues is about 30% to 75%. However, autopsy studies have shown that the prevalence is as high as 80% to 100% (11). NETs without function are more common than functional tumors. Moreover, because approximately 25% of MEN1 patients die from cancer due to malignant gastrinomas (1), an examination of the gastroduodenum is necessary. Serum pepsinogen I and gastrin 17 (GAS-17) were increased significantly (547 µg/L, normal range 70–150 µg/L; 78.6 pmol/L, normal range 0.01–5 pmol/L, respectively). The antibody result for Helicobacter pylori infection was negative.
Gastroscopy showed multiple submucosal uplifts (the largest was about 0.6 x 0.8 cm) at the junction of the duodenal bulb and the descending part of the duodenum (Fig. 1g1). A distal shallow ulcer in the descending part of the duodenum was about 1.0 x 0.5 cm in size (Fig. 1g2). The pathological diagnosis was moderate inflammation and erosion of the descending part of the duodenum. Duodenal gastrinomas in MEN1 syndrome are usually small (smaller than 1 cm), multifocal, and occur mainly in the proximal duodenum (9). Therefore, no obvious gastrinoma lesions were found during the gastroscopy.
Known as Zollinger-Ellison syndrome (ZES), peptic ulcer disease can be caused by functioning NET-secreting gastrin because of increased gastric acid secretion (9). As a result of the increased level of gastrin 17 and the occurrence of duodenal ulcers, the proband was likely to have had gastrinomas.
Whole exome sequencing
In 90% of cases, MEN1 is usually inherited from the affected parent; the other 10% of cases occur by de novo mutation. Germline inactivating mutations of the MEN1 gene on chromosome 11 is the main cause of MEN1 (9). To determine whether the gene had changed, the proband and six relatives had exon sequencing and bioinformatics analysis.
The WES results of the first experiment (NM_130802-1F, NM_130802-1R) showed that the proband (II-3), her sister (II-1), and her niece (III-1) had c.201delC change of NM_130802 in exon 2, which caused amino acid changes (p.Ala68Profs*51) that led to MEN1. Interestingly, the genetic changes were homozygous mutations (Fig. 2, MEN1-Exon2-1F, 1R). No genetic mutations were found in the other relatives. However, we analyzed the patient’s family pedigree, and neither the mother (I-1) nor the son (III-2) of the proband had this genetic mutation. This result was not consistent with Mendelian genetic law. Therefore, we commissioned a technician to redesign a part of the primers (MEN1-Exon2-2R). We retested the samples and got the same result (c.201delC) (Fig. 2, MEN1-Exon2-2F, 2R).
Beijers et al. (12) found a germline and somatic mosaicism in a family with MEN1. They analyzed the blood using MLPA, which showed a minimal but consistently decreased signal for the MEN1-specific MLPA probes. The results from the MLPA trials on the proband (II-3) and her son (III-2), her sister (II-1), and her niece (III-1) were normal. This demonstrated that the gene deletion was absent in the MEN1 of this family (Fig. 3).
A Chinese family presenting with MEN1, with a heterozygous mutation c.825-1G>A and a mutation in intron 5 (IVS 5-1 G>A) of the MEN1 gene, was considered by Zhiwei Ning et al. (13). Considering the possibility of an intron change, we redesigned the primer (NM_130802-3F, NM_130802-3R) in the middle of exon 2 and redetected with the WES test. It turned out that the proband, her sister, and her niece had heterozygous genetic mutations (c.201delC, p.Ala68Profs*51) in exon 2 of chromosome 11 (chr11:64577381), which is consistent with Mendelian genetic law (Fig. 2, MEN1-Exon2-3F, 3R).