Severe heterotopic ossification after total hip arthroplasty in Schnitzler syndrome.

Schnitzler syndrome is a rare disorder characterized by monoclonal IgM gammopathy, urticaria, recurrent fever, evidence of inflammation, bone pain, and arthralgia. We present the case of a patient affected by Schnitzler syndrome who developed Della Valle type C heterotopic ossification after total hip arthroplasty. A relationship between the underlying syndrome and the considerable heterotopic ossification observed is compatible with the patient's clinical history and incidental findings. We suggest prophylaxis against heterotopic ossification when performing hip arthroplasty on patients with Schnitzler syndrome.