SUN-481 - Adrenal Incidentaloma Associated with Lynch Syndrome: Screening Considerations - A Case Report

Lynch syndrome (LS) is a hereditary cancer syndrome primarily associated with
colorectal and endometrial malignancies. Emerging evidence indicates that
adrenocortical carcinoma (ACC) is part of the LS tumor spectrum, with LS prevalence
among ACC patients (~3%) exceeding that of the general population (~0.2%). Despite
ACC’s aggressive behavior and improved outcomes with early surgical resection,
routine adrenal surveillance in LS is not currently recommended, potentially delaying
diagnosis of early-stage disease.
A 43-year-old woman with genetically confirmed Lynch syndrome (pathogenic DNA
mismatch repair gene variant) was incidentally found to have a left adrenal mass on
surveillance imaging. In 2016, PET/CT demonstrated a 1.0 cm lipid-rich adrenal
adenoma. On follow-up CT in September 2025, the lesion enlarged to 3.0 cm with
increased unenhanced attenuation (50–70 HU), concerning for malignant
transformation. The patient was asymptomatic, and comprehensive hormonal
evaluation, including overnight 1-mg dexamethasone suppression testing, two 24-hour
urine free cortisol collections, plasma metanephrines, aldosterone, renin, and DHEA-S, was normal, confirming a nonfunctional tumor. Family history was notable for LS-
associated malignancies, and past medical history included breast cancer at age 34
treated with bilateral mastectomies, chemotherapy, and radiation. Over nine years of
surveillance, progressive tumor growth and loss of lipid-rich imaging features suggested
malignant potential given biochemical inactivity, a pattern described in a
subset of adrenocortical carcinomas. No metastatic disease was identified. Given the
patient’s LS status and concerning radiographic evolution, early-stage adrenocortical
carcinoma was strongly suspected, and adrenalectomy was planned following repeat
adrenal-protocol imaging in early 2026; pathology was pending at submission.

This case supports ACC as an LS-associated malignancy and demonstrates that
adrenal lesions in LS may progress, despite initial imaging demonstrating benign
features. Given ACC’s poor prognosis, in the advanced stage and lack of formal screening
recommendations, heightened clinical vigilance and consideration of adrenal
surveillance in LS patients may enable earlier detection and curative intervention.

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