Small adrenal incidentaloma becoming an aggressive adrenocortical carcinoma in a patient carrying a germline APC variant

Abstract

Purpose: Recent guidelines on adrenal incidentalomas suggested in patients with an indeterminate adrenal mass and no significant hormone excess that follow up with a repeat noncontrast CT or MRI after 6-12 months may be an option.

Methods: We report the case of a 32-year-old woman who presented with a 2.9 × 1.9 cm left adrenal incidentaloma that was stable in size for 4 years. Ten years later the left adrenal mass was a stage IV adrenocortical carcinoma (ACC).

Results: In 2006, a 32-year-old French Canadian woman was referred to endocrinology for a left 2.9 × 1.9 cm incidentally discovered adrenal mass (31 HU). She had normal hormonal investigation. The patient was followed with adrenal imaging and hormonal investigation yearly for 4 years and the lesion stayed stable in size over the 4 years. Ten years later, in 2016, the patient presented with renal colic. Urological CT unexpectedly revealed that the left adrenal mass was now measuring 9 × 8.2 cm and 2 new hepatic lesions were found. Biochemical workup demonstrated hypercorticism and hyperandrogenemia: plasma cortisol after 1 mg overnight DST of 476 nmol/L and DHEA-S of 14.0 μmol/L (N 0.9-6.5). Twenty-four hour urine steroid profiling was consistent with an adrenocortical carcinoma (ACC) co-secreting cortisol, androgens and glucocorticoid precursors. The diagnosis of ACC with hepatic ACC metastases was confirmed at histology. Following genetic analysis, germline heterozygous variant of uncertain significance (VUS) was identified in the exon 16 of the APC gene (c.2414G > A, p.Arg805Gln). Immunohistochemical staining's of the ACC was positive for IGF-2 and cytoplasmic/nuclear β-catenin staining.

Conclusions: This case illustrates that (1) small adrenal incidentaloma stable in size may evolve to ACC and (2) better genetic characterization of these patients may eventually give clues on this unusual evolution.

Keywords: APC gene; Adrenal incidentaloma; Adrenocortical carcinoma.