"Epithelioid" vascular cells in lymph nodes and evidence of glomus structures.

Examination of more than 9,000 lymph nodes by light microscopy has shown epithelioid cell nests in 40 (6.7%) of 600 surgical specimens from operations for breast carcinoma. Such epithelioid cell nests have occasionally been described as "benign nevus cells in the capsule of lymph nodes". The present study shows that such cell foci are relatively frequent and that they originate from cells in the vascular walls. This vascular origin makes the observed spectrum of such structures glomus-like. They can often be identified at several foci and especially in the trabecular reticulum of a lymph node capsule. They measure between 35 microns and 150 microns and may be compared with capillary arteriovenous anastomoses. Five foci showed increased cellularity and even a tumorous expansion into the corticopulpal zone measuring up to 1,500 microns across. With the demonstration of a matrix of vascular muscle cells beneath the glomus-like structures, the relatively rare tumors are defined as "nodular capillary glomus cell proliferations".