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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)

Year: 2026

Type: article

Abstract: 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.

Source: Diagnostics

DOI: 10.3390/diagnostics16081185