Focal cutaneous mucinosis after knee replacement: A rare entity successfully treated with intralesional polidocanol

INTRODUCTION Cutaneous focal mucinosis is a heterogeneous disorder characterized by abnormal deposition of mucin within the skin. It can be primary (idiopathic) or secondary (associated with a neoplasm or inflammation). Mucin is an amorphous, gelatinous substance important for the homeostasis of ground substance and joint fluid. It consists of hyaluronic acid and is usually produced by fibroblasts or synovial cells. Resorption of intra-articular fluid typically occurs through uptake by blood vessels, lymphatics, and perineural spaces. There is a paucity of published cases of cutaneous mucinosis developing adjacent to replaced joints. Apart from presenting our patient, we review the literature, propose the pathogenesis, and suggest treatment for this unusual cutaneous presentation.