The purpose of this report is to add a case of hemangioma of the knee joint to the few that have already been reported and to reemphasize the differential points and the care which must be observed in distinguishing this condition from hemophilic "arthritis" and other more common swellings of the knee joint.
It is probably safe to state that few hemangiomas of the knee joint are diagnosed immediately, even by experienced physicians. There are several reasons for this lack of accurate diagnoses, in spite of the fact that the clinical picture is rather characteristic, as will be seen later. The disease is rare, the symptoms are relatively nondisabling and nonprogressive and their occurrence is characteristically cyclic. No attempt will be made to review the literature, since Bennett and Cobey1 have summarized the cases reported in the literature before 1939. At the time of their report 29 authentic cases,