Age / Sex : 61 / M

Chief complaint: Slow growing, painless mass of lower leg for 1 month.

History of trauma and peroneal nerve injury 30 years ago.

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Please submit only one answer)

Courtesy: Sung Moon Lee, Keimyung university Dongsan hospital

Calcific Myonecrosis

Discussion

Findings:

1.     Cystic mass with irregular thick, shell-like calcification involving entire anterior compartment and distal deep posterior compartment of lower leg.

2.     Peripheral nodular enhancement

3.     Intermediate signal intensity central fluid signal intensity without enhancement

4.     Atrophy of deep posterior and peroneal compartment

Differential Diagnosis:

1.     Malignant tumor, such as synovial sarcoma or soft tissue osteosarcoma
-- calcification is not limited to the periphery, and is commonly juxtarticular
-- central enhancing lesion

2.     Myositis ossificans
-- within injured muscle
-- short history

3.     Post-traumatic aneu ry sm
-- would show marked enhancement

4.     Diabetic myonecrosis, dermatomyositis, polymyositis, calcinosis of CRF, tumoral calcinosis
-- systemic features
-- distinct radiographic features of their own

Diagnosis:  

Calcific myonecrosis

Discussion:

1.     Calcific myonecrosis is a rare and late sequela of compartment syndrome, which becomes symptomatic decades after the initial trauma

2.     Slow-growing, usually painless mass in a previously injured limb (lower limb in most cases)

3.     Fusiform shell-like calcification surrounding entire muscle compartment(s) that undergone complete necrosis and liquefaction

4.     Minor peripheral enhancement, no central enhancement

5.     Pathogenesis is unknown. The current hypothesis is one of necrosis within muscle compartment(s) that have suffered compartment syndrome followed by recurrent intralesional hemorrhage and calcification.

6.     Imaging in the context of history is pathognomonic.

References:

1.     De Carvalho BR. Calcific myonecrosis: A two-patient case series. Jpn J Radiol 2012; 30:517-521

2.     Okada A, Hatori M, Hosaka M, Watanuki M, Itoi E. Calcific myonecrosis and the role of imaging in the diagnosis: A case report. Ulsala J Medical Science 2009; 114:178-183

3.     Dhillon M, Davies AM, Benham J, Evans N, Mangham DC, Grimer RJ. Calcific myonecrosis: a report of ten new cases with an emphasis on MR imaging. Eur Radiol 2004; 14:1974-1979

4.     Tuncay IC, DemirÖrs H, Isiklar ZU, Agildere M, Demirhan B, Tandogan RN. Calcific myonecrosis. International Orthopaedics 1999; 23:68-70