A 61-year-old woman was referred to the radiology department for imaging of her right lower leg because of a painless slowly enlarging mass. Clinical examination also revealed a less pronounced mass in the left antetibial region. Anamnesis revealed a remote trauma 34 years ago during rock and roll dancing.
Fig. 1. Anteroposterior (Fig. 1.a) and lateral (Fig. 1.b) radiographs show plaque-like soft tissue calcifications parallel in the anterior compartment of the lower leg.
Fig. 2. Ultrasound shows echogenic foci (arrowheads) with retro-acoustic shadowing.
Fig. 3. Axial (Fig. 3.a) computed tomography images of both legs demonstrate bilateral calcifications in the anterior compartment of the lower leg. The peripheral rim (arrows) of the lesions is denser than the central part. Sagittal reformatted image of the right leg (Fig. 3.b) shows the plaque-like calcifications.
Fig. 4. Axial T1-weighted images (WI) without (Fig. 4.a) and with (Fig. 4.b) fat suppression show areas of intermediate signal intensity in the mass (arrows) left more than right because of the higher calcified content. A low intensity rim is present at the periphery of the lesion (arrowheads) on T1-WI. Coronal T2-WI (Fig. 4.c) shows the fusiform shaped mass with heterogeneous signal intensities in both lesions (arrows).
Calcific myonecrosis is a rare benign post-traumatic lesion, which may mimic a soft tissue tumour [1]. Anamnestic information of a remote trauma is usually present. Time of onset ranges between 10 and 64 years [2]. Reduced circulation due to compartment syndrome leads to necrosis and fibrosis within a confined area in the muscle and central liquefaction may occur. Enlargement and calcification of the intramuscular mass is attributed to repeated haemorrhages or herniation of the mass through the muscle fascia [3]. The most frequently involved muscles are those located in the anterior compartment of the lower leg. The lesion typically involves one limb, but bilateral presentation - as in our case - has been described occasionally [4].
Plain radiographs show a fusiform mass along with the long axis of the muscles with peripheral calcifications, often with a linear plate-like configuration. Ultrasound demonstrates scattered but predominantly peripherally located calcifications visible as echogenic foci with retro-acoustic shadowing. Central areas of liquefaction or mobile calcium debris may also be seen. Computed tomography (CT) clearly depicts the compartmental distribution with peripheral calcifications and sometimes fluid calcium levels or bone erosions due to chronic pressure effect. On MRI the periphery of the lesion shows a low intensity rim on T1-WI because of abundant calcification. T1-and T2-WI demonstrate the heterogeneity of the lesion explained by repeated intralesional haemorrhage with accumulation of blood (breakdown) products, liquefaction necrosis and calcified areas. Hyperintensity on T1-WI is the result of subacute haemorrhage with subsequent haemoglobin degradation to methaemoglobin or the presence of a proteinaceous content of cystic parts in the lesion. The lesion may also show hyperintense areas on T2-WI corresponding with cystic parts or liquefaction necrosis. Other parts of the lesion demonstrate intermediate to low signal intensity according to the degree of calcification [1, 3, 4].
The differentiation between a calcified soft tissue tumour and pseudotumoural calcifications within the soft tissue is crucial. The former category includes synovial sarcoma, epitheloid sarcoma, soft tissue osteosarcoma and the latter myositis ossificans, posttraumatic pseudoaneurysms, tumoural calcinosis, calcified abscess and systemic disease such as dermatomyositis, polymyositis and diabetic myonecrosis [3, 5].
Treatment is conservative for painless and asymptomatic lesions but surgery remains the treatment of choice for pain resistant lesions [6].
Key imaging features for diagnosis consist of the fusiform morphology of the lesion with typical plate- or plaque-like peripheral calcifications with central liquefaction, the location of the lesion and the history of a remote traumatic event.
Calcific myonecrosis
Based on the provided X-ray, CT, and MRI images, spindle-shaped soft tissue masses are observed in both anterior muscle compartments of the lower legs. The lesions appear as elongated or spindle-shaped structures along the longitudinal axis of the muscle, with laminar or patchy calcifications visible around the margins. CT images show that the lesions are primarily located within the fascial compartment of the muscles, with evident calcific or sclerotic borders at their periphery. The central area exhibits relatively low density, consistent with liquefaction or cystic changes. On MRI, there is a mixture of different signal intensities: in T1-weighted images, some areas present high signal intensity (suggesting chronic hemorrhagic components), while other parts exhibit isointense or hypointense signal (indicating fibrotic or calcified regions). In T2-weighted images, relatively high signal areas suggest cystic or liquefactive components, while low signal areas indicate calcification and fibrotic elements. Overall, the lesions match features of chronic recurrent bleeding, calcification, and liquefaction.
Combining the imaging findings with the patient's clinical history, the following diagnoses or differentials may be considered:
Considering the patient’s history of trauma 34 years ago while dancing (indicating a remote injury), the presence of spindle-shaped calcified masses in both anterior muscle compartments of the lower legs, evidence of repeated bleeding or liquefaction in the tissues, and the chronic, painless nature of the lesions, the most likely diagnosis is Calcific myonecrosis.
To definitively exclude malignancies or other suspicious lesions, local biopsy and histopathological examination may be conducted if clinically warranted.
Treatment Strategy:
For calcific myonecrosis that is minimally symptomatic and does not significantly impact function, conservative observation can be adopted (including regular imaging follow-up to assess lesion stability). If pain, nerve compression, or functional impairment arises, surgical excision of the lesion may be considered.
Rehabilitation and Exercise Prescription Suggestions:
1) Initial Phase: Perform gentle lower limb functional exercises, such as seated leg raises, ankle mobilization, and mild leg stretches, once or twice a week for 10–15 minutes each session, ensuring no exacerbation of pain or disease.
2) Progressive Phase: If the patient tolerates well, gradually increase exercise intensity, such as standing calf stretches and low-intensity resistance band training for lower limbs, 2–3 times a week, 15–20 minutes each session.
3) Strengthening Phase: Once pain and functional limitations are under control, undertake lower limb strengthening and balance training guided by a physical therapist. This may include moderate resistance band exercises or light weighted squats, 3 times a week, 20–30 minutes each session. Ensure proper form and safety to prevent re-injury.
4) Individualized Monitoring: Adjust the frequency, duration, and intensity of training (according to the FITT-VP principle) based on the patient’s condition (bone health, cardiovascular function, comorbidities, etc.). Seek medical attention if aggravation of pain or other discomfort occurs.
This report is based solely on the provided medical history and imaging data for reference and does not replace in-person consultation or professional medical decision-making. All treatment or rehabilitation measures should be carried out under the guidance of qualified healthcare professionals. If you have further questions or experience discomfort, please seek medical advice promptly.
Calcific myonecrosis
