Papillary Thyroid Carcinoma, Bilateral Macronodular Adrenal Cortical Disease-Related Cortisol Excess, and Femoral Enchondroma: A Novel Phenotype-Genotype Based on Next-Generation Sequencing (Variants of APC, MSH6, and CACNA1S Genes).

This case highlights a novel genotype-phenotype correlation in the field of endocrinology. Specific endocrine and imaging assessment, in addition to next-generation sequencing (NGS), was performed on the Illumina MiSeq platform, using a TruSight One Sequencing Panel kit for genomic analysis of coding regions of 4813 genes. A 54-year-old female was confirmed with a papillary thyroid carcinoma after total thyroidectomy and underwent radioiodine ablative therapy. Three years later, a left femoral enchondroma of almost 3 cm was identified at computed tomography (CT) scan and magnetic resonance imaging (MRI). She experienced hypertension (in addition to obesity, dyslipidaemia and impaired glucose tolerance) and was later confirmed with ACTH-independent cortisol excess [lack of cortisol suppression at 1 mg dexamethasone testing of 13.9 (normal < 1.8 µg/dL)], noting bilateral adrenal tumors, of 4.7 cm (right), respectively, and of 1.6 cm (left) at CT. Right laparoscopic adrenalectomy was performed with post-operative adrenal insufficiency, requiring glucocorticoid replacement and stopping the anti-hypertensive medication. Pathology report confirmed an adrenocortical adenoma (a Ki67 proliferation index of 2%). Noting the unusual association of the mentioned conditions, NGS was performed in the peripheral blood and identified a heterozygote missense variant of the APC gene (c.5759G>A, p.Arg1920Gln), a heterozygote missense variant of the MSH6 gene (c.2092C>G, p.Gln698Glu), and an incidental additional finding: a heterozygote stop gain pathogenic variant of the CACNA1S gene (c.2707C>T, p.Arg903*). The first two are currently classified as variants of uncertain significance. Whether the co-presence of a triple mutation may change the clinical picture and the life-long outcomes across reciprocal influence is still an open matter. Further research will point out the clinical implications of this genotype-phenotype association, which, to our best knowledge, has not been previously reported.