E1019. Calcific Myonecrosis: Imaging Features
  1. Wisam Witwit; St. Joseph Mercy Oakland
  2. George Pappas; St. Joseph Mercy Oakland
Calcific myonecrosis refers to a rare post-traumatic phenomenon. It is characterized by latent formation of a dystrophic calcified mass occurring almost exclusively in the lower limb. Calcific myonecrosis can be confused with a neoplastic process given its heterogeneity.

Educational Goals / Teaching Points
Highlight the imaging features of calcific myonecrosis. This entity's heterogeneous appearance can raise suspicion for sarcoma rendering biopsy as a potential method for further investigation. Radiologists have to be confident in diagnosing this entity based solely on imaging features. Biopsy should be avoided because of the high risk of converting the sterile necrotic tissue into an abscess.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Calcific myonecrosis can appear as a heterogeneous mass decades after the inciting trauma. The key diagnostic features include location almost exclusively in the leg and imaging appearance demonstrating sheet-like peripheral calcifications. Evidence of remote trauma such as bullet fragments is another factor leading to the correct diagnosis. Calcific myonecrosis can be differentiated from myositis ossificans which commonly demonstrates more mature trabecular and lamellar calcifications progressing centrally. Additionally, myositis ossificans occurs weeks to a few months after trauma.

Calcific myonecrosis can be diagnosed when a mass in a single muscle, or muscle compartment, demonstrates the characteristic distinct peripheral sheet-like calcifications with history of remote trauma. Biopsy should be avoided because of the high risk of converting sterile necrotic tissue into an abscess.