Soft-Tissue Radiography of Axillary Nodes with Fatty Infiltration

Abstract

Fatty Infiltration or lipomatosis of the lymph nodes can be defined as a proliferation of the adipose tissue which grows in the node from the hilus toward the cortical zone, producing distention of the capsule and causing atrophy of the lymphoid tissue. This condition is very common, especially in the aged, and occurs as a rule in the mesenteric, abdominal, and axillary nodes (1). Fatty infiltration of the axillary nodes may sometimes attain considerable volume, with the clinical appearance of a neoplasm. In such cases soft-tissue radiography of the axilla has proved of value. We have been able to visualize successfully the lymph nodes, with positive and differential diagnosis of fatty infiltration. Technic To demonstrate axillary lymph nodes without the use of intralymphatic contrast medium, a soft-tissue technic which has been described elsewhere in detail must be employed (2). Briefly this includes: (a) adequate beam direction with compression and position of the patient such that the axillary region is projected away from the shadow of the latissimus dorsi muscle, (b) low kilovoltage, approximately 25 kv, and (c) Kodak medical nonscreen film. Results Metastatic lymph nodes, primary lymphatic tumors, and nonspecific adenopathies appear as rounded shadows with a uniform density. Conversely, lymph nodes with fatty infiltration have a central radiolucent area surrounded by the radiopaque lymphoid tissue which has been displaced peripherally (3, 4). Figure 1 shows six different radiographic aspects of these nodes observed by the authors. These features, relative to the topography and degree of fatty infiltration, may be eccentric or centrally located, with shadows comparable to crescents, sickles, or rings (Figs. 2 and 3). As the fatty infiltration increases, the rim of lymphoid tissue decreases in width and may even disappear, leaving only the distended capsule. The ring is generally smooth, but sometimes may show lobulated contours (Figs. 4 and 5). These radiographic shadows are clearly demonstrated on the original films, but good reproduction for publication is difficult to obtain. None of the accompanying illustrations reveal the lymph nodes as well as the original films, in spite of the use of the LogEtron in preparing the reproductions. Discussion In every radiographic examination of the axilla, mammography should also be performed because of the frequent association of axillary nodes and a malignant condition of the breast. Moreover, a high diagnostic accuracy can be obtained with the mammographic technic developed by one of the authors (5, 6). It is recognized that while the presence of an enlarged lymph node with fatty infiltration does not exclude the possibility of metastases, it does imply that the palpable mass is largely nonmetastatic.