Preliminary Report: The Relevance of Tumor Necrosis Factor-α in Acquired Primary Lymphedema-A Histopathological Investigation.

Background

Lymphedema includes primary lymphedema (P-LE) and secondary lymphedema (S-LE), which is a chronic progressive disease. The former group is further classified as congenital and acquired P-LE (AP-LE); its etiology is unclear, and only a few studies on its pathophysiology exist. We hypothesized that an autoimmune disease or self-inflammatory mechanism occurs in lymphatic vessels, leading to obstruction. Methods and

Results

We enrolled 46 patients with lymphedema who underwent lymphaticovenous anastomosis (LVA) from January to October 2015. Collecting lymph ducts were obtained during LVA. We performed hematoxylin/eosin staining and immunostaining for LYVE-1, IL-1β, IL-6, and TNF-α. There were no substantial histological differences between the two types of lymphedema, whereas some differences in expression of inflammatory cytokines, including interleukin (IL)-1β and tumor necrosis factor (TNF)-α, were observed. Only a few inflammatory cells could be seen around the vessels. Although no significant differences in expression of IL-1β were found between AP-LE and S-LE, TNF-α was more highly expressed in the smooth muscle layer in AP-LE patients than in S-LE patients. There were no significant morphological differences in the collecting ducts of lymphatic vessels between S-LE and P-LE. Nevertheless, higher levels of TNF-α accumulation were found in the thick smooth muscle layer of P-LE patients than in that of S-LE patients.

Conclusion

TNF-α-related inflammation in collecting ducts of lymphatic vessels is an important characteristic of the pathology of P-LE. TNF-α inhibitors might improve symptoms of AP-LE.