Pheochromocytoma in NF1 occurs in older patients with no family history compared to other syndromes; it is mostly unilateral, secretory and benign. The older age at diagnosis of PHEO could be secondary to delay in identification due to lack of systematic screening for PHEO in NF1.
Laboratory interference is a drawback in hormonal testing, and clinicians should have a high index of suspicion when faced with biochemical results discordant with the patient's clinical manifestations. A 62-year-old postmenopausal woman initially consulted her primary care physician for mood lability; laboratory workup showed markedly elevated levels of total serum estradiol, progesterone, testosterone, and cortisol as measured by immunoassay. Further investigation demonstrated no evidence of estrogen effect on uterus, no adrenal or adnexal mass, and no evidence of Cushing syndrome. Conventional techniques to unmask laboratory interference, such as dilution, antigen precipitation, and using a different immunoassay did not unveil a potential laboratory interference. The patient had no apparent risk factor for analytic interference, such as absent rheumatoid factor and heterophilic antibodies, but had only mild monoclonal IgG hypergammaglobulinemia. In this case, mass spectrometry unmasked the false elevation in steroid hormones. Interference of gammaglobulins or antibodies with the labeling and separation process of the assay could be the culprits. In conclusion, we report a unique case of multiple steroid hormones elevations due to laboratory interference unmasked by mass spectrometry.
Objective
Pheochromocytomas (PHEOs) and paragangliomas (PGLs), collectively known as PPGLs, are tumours with high heritability. The prevalence of germline mutations in apparently sporadic PPGLs varies depending on the study population. The objective of this study was to determine the spectrum of germline mutations in a cohort of patients with apparently sporadic PPGLs over time.
Design
We performed a retrospective review of patients with apparently sporadic PPGLs who underwent genetic testing at our referral centre from 2005 to 2020.
Patients: We included patients with apparently sporadic PPGLs who underwent genetic testing at our referral center.
Measurements: Genetic analysis included sequential gene sequencing by Sanger method or next generation sequencing (NGS) with a multigene panel.
Results
The prevalence of germline mutations was 26.2% (43/164); 40.0% (30/75) in PGLs and 14.6% (13/89) in PHEOs. We identified four novel pathogenic variants (two SDHB and two SDHD). Patients carrying germline mutations were younger (38.7 vs. 49.7 years old) than patients with no identified germline mutations. From 2015 to 2020, we performed NGS with a multigene panel on 12 patients for whom the initial genetic analysis was negative. Germline mutations in previously untested genes were found in four (33.3%) of these patients (two MAX and two SDHA), representing 9.3% (4/43) of the mutation carriers.
Conclusion
The prevalence of germline mutations in our cohort of patients with apparently sporadic PPGLs was 26.2%. Genetic re‐evaluation over time using multigene sequencing by NGS assay in a subgroup of patients leads to an increase in the detection of mutations.
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