CT and ¹⁸F- FDG-PET-CT Findings in Secondary Adrenal Lymphoma with Pathologic Correlation

To evaluate computed tomography (CT) and positron emission tomography-computed tomography (PET-CT) imaging manifestations of lymphomas secondarily involving the adrenal gland.

Seven patients (Five men, two women; median age [range], 66 years [34-75 years]) with pathologically proven adrenal lymphoma were assessed retrospectively. Clinical findings, prior history of lymphoproliferative malignancy, CT (n = 7) and fludeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG-PET-CT) (n = 6) features were analyzed.

Six cases were diffuse large B-cell lymphoma, and one case was peripheral T-cell lymphoma. The longest diameter of the lesions ranged from 3.2 to 6.6 cm (median 4.3 cm). Six lesions were well-defined and one lesion was ill-defined. In five cases, an adreniform shape was preserved. No lesions contained fat, calcification or hemorrhage. Two lesions had necrosis on CT. Median (range) unenhanced CT density of six lesions was 31.8 (29.2-35.2) Hounsfield units. Following administration of IV contrast media (n = 6), three lesions enhanced homogenously whereas three enhanced heterogeneously. The median increase in attenuation was 35.1 Hounsfield units. Two patients had 15-minute delayed CT and they both demonstrated limited wash-out consistent with nonadenoma. Six patients had fludeoxyglucose positron emission tomography-computed tomography(^18-F-FDG-PET-CT) and all lesions were fludeoxyglucose (FDG) avid with a median SUV_max of 18.6 (range: 10.3-49.2).

Secondary adrenal lymphomas usually manifest as, large (>3 cm), well-defined, homogenously or slightly heterogeneously enhancing masses on CT with preserved adreniform shape. These lesions tend to show limited wash-out and high fludeoxyglucose (FDG) uptake.