Marginal-Zone Lymphoma Mimicking Adrenal Myelolipoma on Computed Tomography Scan

Abstract

A 69-yr-old woman was referred for a left adrenal mass incidentally discovered at computed tomography (CT) scan that was performed for abdominal pain. Clinical examination showed no signs of corticosteroid or catecholamine excess, and hormone assays revealed no abnormality. At CT scan, the lesion appeared as a 6-cm heterogeneous mass containing low-density fat surrounded by dense tissue (Fig. 1A). The neoplasm was associated with infiltration of the left perirenal fascia evocative of an inflammatory process (Fig. 1B). The diagnosis of adrenal myelolipoma complicated by extracapsular hemorrhage was suggested (1), and surgical removal of the lesion was performed through retroperitoneoscopy. Pathology showed no adrenal neoplasm but revealed an invasion of the periadrenal fat tissue by proliferation of monomorphic small lymphocytes (Fig. 1, C and D, and Fig. 2A). Immunolabeling of the tissue (Fig. 2, B and C) allowed establishing the diagnosis of marginal-zone B-cell lymphoma (MZL). Staging procedures showed involvement of spleen and bone marrow. Considering the good prognosis of MZL, therapeutic abstention was decided. Non-Hodgkin’s adrenal lymphomas are usually diffuse extranodal large B-cell lymphomas with poor prognosis. When bilateral, destruction of the adrenals by the proliferative lymphocytic process frequently results in adrenal insufficiency (2). Very rarely, lymphomas of the adrenal areas belong to the MZL subtype, also called small B-cell lymphoma (2, 3). MZLs arise from a marginal-zone B cell present in lymph nodes and extranodal tissues and are considered as indolent malignancies (3). In the patient’s case, invasion of periadrenal fat tissue by lymphocytic proliferation mimicked the appearance of adrenal myelolipoma on CT scan, i.e. a heterogeneous mass with mature fat intermingled with dense myeloid tissue (4).