Adrenal myelolipoma: Defining the role of surgery. A case report

Adrenal myelolipomas (AMLs) are rare, non-functional, benign tumours mostly diagnosed incidentally. They present as small and unilateral masses that are histologically composed of mature adipose tissue with admixed haemopoietic elements. In a small percentage of patients, pressure symptoms, retroperitoneal haemorrhage or tumour rupture may occur. However, indications for surgery in the majority of asymptomatic patients are poorly defined.

A 44-year old male patient presented with signs of gastroenteritis. Computed tomography (CT) imaging revealed an encapsulated, sharply delineated mass measuring 87 × 76 × 87 mm displacing the right adrenal gland. Average attenuation was -30 Hounsfield units. Given the pathognomonic features, an AML was suspected. The patient underwent open tumour resection and the diagnosis was histologically confirmed.

Small (<4 cm), homogeneous, non-hormone secreting incidentalomas with an attenuation of <10 Hounsfield units on non-contrast CT are considered benign requiring neither treatment nor follow-up. Giant AMLs (>10 cm) may cause symptoms or complications and are therefore considered candidates for surgery. The treatment strategy of asymptomatic AMLs ranging from 4 cm to 10 cm, however, is controversial and poorly defined. The role of surgery in this specific subgroup of patients is studied.

Surgery is indicated in the presence of a tumour diameter above 6 cm, rapid tumour growth (RECIST 1.1 criteria for progressive disease at 6-12 months follow-up), imaging suspicious of malignancy, radiological signs of local invasion, functioning ipsilateral adrenocortical adenoma, pressure-related symptoms and signs of retroperitoneal bleeding or spontaneous tumour rupture.