Adventitial Cystic Disease Communicating with the Knee Joint: A Case Report with Histopathological Study of the Connection.

Adventitial cystic disease is a rare nonatheromatous cause of popliteal artery disease. Here, we present a case of a 51-year-old male patient who presented with right calf claudication caused by adventitial cystic disease. Preoperative magnetic resonance imaging and intraoperative findings revealed the presence of a connection between the cyst and adjacent knee joint. In addition, histopathological examination revealed that the tissue structure of the connection was similar to that of adventitial cysts. The tissue composed of 2 types of cells, namely macrophages and fibroblast-like cells, and lesional cells expressed D2-40. These findings supported the ganglion theory as the underlying physiopathology of this disease and were helpful in deciding the management of this case.