From Adenoma to Carcinoma: the Unexpected Evolution of an Apparently Stable Adrenal Lesion

There is a lack of solid long-term evidence with respect to the management over time of adrenal incidentalomas that miss clearly benign radiological features. We present the case of a 75-year-old man with a non-secreting adrenal mass, apparently stable in size (14 mm) and unchanged in features for 2 years, but subsequently diagnosed as adrenal carcinoma.

The patient was referred to Grande Ospedale Metropolitano Niguarda in August 2022 due to the presence of a large lesion in the left adrenal site. In 2017, a 14 mm, 20 HU, round, regular-edged lesion was detected at a CT scan without contrast medium. Over the next two years, the patient was re-evaluated every 6 months with follow-up CT scans with no apparent densitometric or dimensional changes in the known lesion. In September 2022, 3 years after the last CT scan, the patient was hospitalised for pneumonia. An abdominal CT scan acquired during the hospitalisation showed an increase of the lesion to 14.5x10x12 cm. The patient subsequently underwent open nephrosurrenectomy, and histological examination confirmed the presence of an adrenal carcinoma (proliferation index 5%, Weiss score 7). No adjuvant therapy was administered, and the last CT scan in December 2022 was negative for the recurrence of the disease.

Adrenal carcinoma usually presents as a clearly malignant lesion with rapid growth and a marked tendency to metastasise. This case highlights how an adrenal adenoma with indeterminate features is worthy of follow-up over time despite its apparent dimensional and radiological stability [1].