Teaching Case

A 95-year-old man was admitted to the emergency room with swelling, redness, and a skin ulcer in the left leg. He had a fracture of the leg at the age of 20. It was interpreted as cellulitis, and the patient began antibiotic therapy. Radiography was performed to assess possible osteomyelitis.

Anteroposterior (Fig. 1a) and lateral (Fig. 1b) radiographs show deformity of the distal third of the diaphysis of the tibia and fibula following traumatic sequelae. Presence of osteosynthesis material in the tibia (five screws).

In the anterolateral region of the leg, an extensive fusiform mass with amorphous and linear calcifications is observed. 

Ultrasound with a high-frequency linear probe (Fig. 2) shows irregular echogenic foci with acoustic shadowing, compatible with calcifications, in the muscular plane. Slight oedema and hyperechoic of the subcutaneous tissue are also noted anomalies in the concomitant cellulitis episode.

Axial (Fig. 3a), coronal (Fig. 3b), and sagittal (Fig. 3c) computed tomography images of the left leg demonstrate extensive fusiform mass in the anterior leg compartment. An eggshell peripheral calcification and amorphous calcifications within the mass are evident.

Calcific myonecrosis is a rare benign disease. It is characterized by the replacement of muscle in one or more compartments with fusiform masses with central liquefaction and peripheral calcification. [1, 2]

The typical area of calcific myonecrosis is the anterior compartment of the leg. It can also occur in the leg’s lateral and deep posterior compartments. Although rarer, there are cases of the forearm. [1, 3]

Most cases are associated with closed fracture, compartment syndrome following trauma, or nerve injury. It is postulated that these lesions result from post-traumatic ischemia, fibrosis of muscles, and recurrent intralesional haemorrhage within a chronically calcified mass. [1]

Diagnosis of these masses is usually formulated several years (30-40 years) after the initial injury.  [4]

Interventions such as biopsy or aspiration are frequently complicated with infection and wound healing problems, occasionally with devastating results. There are no reports of malignant transformation. With a typical medical history (remote fracture, compartment syndrome) and imaging, this is described as a “do not touch” type of lesion. [5, 6, 7]

In radiographs, the characteristic features are mixed areas of radiolucency and amorphous and linear calcifications within an entire muscle or compartment. Sometimes there are bone erosions and smooth periosteal reaction. [1, 8]

Tomography computerized scan usually shows fusiform soft-tissue masses with longitudinal peripheral plaque-like calcifications as eggshell and multiple fragmented calcifications involving the entire compartment. [1, 9]

Magnetic resonance imaging usually shows heterogeneous lesions, with areas of isointense and hyperintense signals due to haemorrhage or proteinaceous material on T1-weighted images, areas of hyperintense on T2-weighted images corresponding to cystic and liquefaction areas, and hypointense coarse calcifications on both T1- and T2- weighted images. There is no enhancement after gadolinium administration within the mass, but it could produce some peripheral ring enhancement. [1, 10, 11]

Asymptomatic patients with stable lesions, typical medical history and imaging should undergo surveillance. [6,7]

Symptomatic patients can undergo surgical excision or debridement with flap coverage, but there is a high risk of complications, the most worrisome of which is infection. There are high rates of reintervention, and some cases will require amputation. [6, 7, 12]

Calcific myonecrosis is a late sequela of trauma to the leg. If clinical history and imaging characteristics are typical, patients should be managed conservatively, avoiding interventional procedures. [5, 7]

Written informed consent from the patient for publication has been obtained.