Can healthy lymph nodes look like cancer on a diagnostic image?

Details

Lymphangiography had been used for many years, on a limited scale, to examine lymphatic channels in lymphedema and related diseases. Its adaptation to visualize lymph node architecture, called lymphadenography, was relatively recent and had focused chiefly on neoplastic disease. Previous authors had documented its value in lymphoma and far-advanced metastatic neoplasms, but detecting early or subclinical metastases would have greater potential. Its reliability for that purpose had not been established, and some authors had questioned its worth.

To evaluate lymphadenography for early neoplastic involvement of lymph nodes, the researchers considered it necessary to learn more about normal lymph node architecture. They stated that no report of lymphadenography in normal persons had yet been published; their purpose was to report findings in such a group.

This was a descriptive observational imaging study. Lymphangiograms were obtained from 8 male and 8 female volunteers from state penal institutions. They were 20–40 years old and in good health. Enrollment required that their history, physical examination, and medical-record review show no evidence of neoplasm or active inflammatory disease.

The procedure followed Kinmonth’s methods as modified by Sheehan et al. and Wallace et al. Direct injection of 10 c.c. of Ethiodol into lymphatic vessels on the dorsum of the foot was performed bilaterally. This made the femoral, inguinal, external iliac, and para-aortic lymph nodes visible with contrast up to the level of the cisterna chyli. Frontal and lateral X-rays of the pelvis and abdomen were taken immediately after injection and again after 24 hours. Node architecture was best seen at 24 hours: the nodes were well filled with contrast, while the overlying lymphatic vessels were free of contrast material in most instances.

For comparison, metastatic deposits in individual lymph nodes had been described as producing irregular marginal filling defects—areas along the edge not filled by contrast. Such nodes could be slightly enlarged or normal in size. In lymphoma, by contrast, prominent node enlargement had been reported, with a mottled, foamy, or lacy appearance.

The healthy participants in this study also had irregularities of lymph node architecture that resembled neoplastic disease. Conspicuous marginal filling defects appeared in one or more nodes in a majority of those examined. Very close inspection revealed smaller defects in virtually all of the series. One healthy participant had an enlarged, mottled node similar to the appearance described in lymphoma. Figure 1 showed nodes from 2 of the few participants without conspicuous filling defects. Thus, appearances described in neoplastic disease were also observed in these healthy volunteers; the reliability of the procedure for detecting early or subclinical metastases remained unestablished.