Smooth muscle proliferation in the hilum of superficial lymph nodes

A retrospective survey to study hilar smooth muscle proliferation was performed on 410 superficial lymph nodes from 130 patients. Smooth muscle proliferation of variable degree was found in a total of 32 patients, affecting both inguinal and axillary nodes. A slight predominance of inguinal lesions was noted, and a higher proportion of nodes from male patients was affected. The smooth muscle proliferation was not age related nor was it associated with metastatic carcinoma. An association between smooth muscle proliferation and prominent hilar vascularity was found. In individual cases where several nodes had been removed, there was a tendency for more than one node to show smooth muscle proliferation, suggesting that there is a locally acting diffusible aetiological agent. We think the smooth muscle proliferation we have described is of vascular origin, and that it may reflect a previous inflammatory reaction.