The patient, a 71-year-old man with a history of diabetes, prostate cancer, and coronary artery disease treated by antiplatelet agent, presented with bilateral knee osteoarthritis previously treated with hyaluronic acid (HA) injections. Without new HA injections for 1 year, the patient underwent a new injection of reticulated HA (Hyalexo cross) in the left knee through external patellar approach, without ultrasound. He presented two days later with a painful reddish violet livedoid eruption on the left knee (A). The eruption progressively became necrotic and extended to reach its maximum at four weeks (B and C). Doppler ultrasonography and blood analysis revealed no pathologic findings. A skin biopsy (D and E, hematoxylin and eosin stain, ×40 in D and ×200 in E) revealed the presence of amorphous foreign intravascular material within deep dermal and hypodermal veins. Given the anatomic-clinical correlation, a diagnosis of livedo reticularis due to intra-articular injection of HA was retained, with tissue necrosis caused by a vascular thrombosis following embolization of the product after injection into a vessel. It is a rare condition, affecting mainly the face after aesthetic procedures, 1 with only four cases reported after intra-articular HA injection. 2,3 Onset varies from 12 hours to 1 month after injection. Our patient showed progressive improvement after hyperbaric chamber sessions and probable natural elimination of HA. Better knowledge and early recognition of this undesirable effect is essential to improve injection techniques and management with potential hyaluronidase injections in early stages.