Pathological Investigation of Acquired Lymphangiectasia Accompanied by Lower Limb Lymphedema: Lymphocyte Infiltration in the Dermis and Epidermis.

BACKGROUND: Sometimes acquired lymphangiectasia (lymphangioma circumscriptum), the pathological mechanism of which is unknown, accompanies lymphedema. The purpose of this study was to better understand the pathological changes present in acquired lymphangiectasia.

METHODS AND RESULTS: We examined the pathological characteristics of acquired lymphangiectasia with lymphedema among patients treated at the University of Tokyo Hospital from March 2008 to December 2015. In total, 16 biopsies from 10 patients were investigated. The average age of the patients was 57.2 years (range 43-69), and all were female with secondary lymphedema. Surgical specimens were fixed in formalin, and tissue sections were stained with hematoxylin-eosin. Additional immunostaining (podoplanin, lymphatic vessel endothelial hyaluronan receptor [LYVE] -1, CD4, CD8, CD20, and CD31) was performed in cases 1-3 and 8-10. Dilation of lymphatic vessels in the papillary dermis was present in all 10 cases. Infiltration of inflammatory cells, most of which were lymphocytes, was also observed in the dermis and the epidermis in all cases, even though there were no clinical signs of inflammation. The infiltrating lymphocytes were mainly CD4+ T cells, and less commonly, CD8+ T cells and CD20+ B cells. The number of three types of lymphocytes was significantly larger in the superficial layer of the dermis than in the deep layer, which may indicate that they oozed out from the dilated lymphatic vessels located in the superficial dermis. CD8+ T cells infiltrated the epidermis in seven of eight specimens. In case 4, coagulated lymphatic fluid inside the lymphatic vessel was observed. Proliferation of collagenous fiber in the dermis and acanthosis were observed.

CONCLUSIONS: Lymphatic dilation and proliferation of collagenous fiber in the dermis were seen in cases of acquired lymphangiectasia (lymphangioma circumscriptum). Constant infiltration of lymphocytes in the dermis and the epidermis may have a relation to frequent cellulitis, which is often seen in lymphedema patients.