A 32-year-old woman came to the outpatient clinic presenting with a 5-month history of pain in the right ankle. There was not history of trauma. There were not physical examination findings.
Ankle radiography showed abnormal cortex of the fibula and tibia, with lytic lesions and cortical thickening; minimal laminar periosteal reaction without fracture and doubtful permeative pattern (Fig. 1).
CT confirmed several cortical lytic punch lesions in the right tibia and fibula, particularly in its lateral side. The permeative pattern was not confirmed. (Fig. 2-4). Associating abnormal soft tissues, with an increased volume of: soleus, flexor hallucis longus, and posterior tibialis, extending to the interosseous membrane, and with fat between the septa (Fig. 5, 6).
RMI showed abnormal vessels in the right leg, from the ankle to the proximal third part of the leg involving posterior calf muscles and extending to the tibiofibular syndesmosis. We also found interosseous drainage vessels causing the cortical punch lesions (erosions) in right tibia and fibula (Fig. 7-14).
The MR dynamic study demonstrated an early arterial mixed component with large drainage veins. Some of these were thrombosed (Fig. 15). There was no evident soft tissue mass.
Multiple myeloma is unlikely in this case because of the age of the patient and metastasis as well because an underlying malignancy was ruled out. Therefore the remaining differential diagnosis were: adamantinoma, though this lesion is more likely to be formed in the anterior cortex layer of the tibia; lesions of vascular lineage (haemangioendothelioma and angiosarcoma, vascular malformations) [1] and osteosarcoma, due to the doubtful permeative pattern; and ultimately granulomatous lesions (sarcoidosis and tuberculosis).
The vascular malformations are categorized in two kinds (although there are more classifications): the high flow ones (arteriovenous fistula and arteriovenous malformation (AVM)) and the low flow ones (venous, lymphatic, capillary, capillary-venous…) [1, 2, 3, 4]. This division is based on the dynamic study and is important for surgical planning and it is an image-guidance for therapeutic procedures. The vascular malformations are congenital abnormalities which are present at birth, although they are not always evident. They usually enlarge while the child grows and do not revert [1, 3]. They get exacerbated in puberty, pregnancy, thrombosis, infection or trauma. Unlike haemangioma, vascular malformations may be infiltrative and affect multiple adjacent planes.
The high flow AVM appears clinically as a red, hot, throbbing mass [3]. It can cause an excessive bone growth due to high blood flow. It can also appear as an arterial blood theft or even cortical erosions [2].
The AVM may be complicated by haemorrhage and thrombosis. They are more common in the central nervous system, followed by the head, the neck, the limbs, trunk and viscera [1, 2].
Histopathologically the AVM are dysplastic vessels that connect the veins and arteries forming a nidus.
The RM shows large feeding arteries, serpiginous, with high blood flow and also draining veins, showing a “flow void” in SE sequences and high signal intensity in GRE sequences.
A well-defined mass is absent. Linear septa of fat intensity signal in the lesion are typically observed.
The dynamic study shows arterial, capillary and venous phase images, identifying an early arterial enhancement in case of AVM [1, 3].
The definitive treatment is a transarterial embolization. It is a condition that should be considered in the differential diagnosis of multiple bone lytic lesions [1, 3, 4].
Teaching points:
1. AVM might be associated to bone cortical lesions secondary to enlarge drainage vessels.
Arteriovenous malformation
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From the provided X-ray, CT, and MRI images of the ankle joint, a localized abnormality can be observed in the distal tibia above the right ankle joint:
Based on the patient’s age (32 years), symptoms (chronic ankle pain), imaging findings, and clinical history (no history of trauma, etc.), the main differential diagnoses include:
Taking into account the patient’s age, symptoms (persistent ankle pain), imaging evidence of a high-flow vascular malformation, and corresponding rapid arterial filling with venous drainage, an arteriovenous malformation (AVM) is supported as the diagnosis.
If further clinical confirmation is required, digital subtraction angiography (DSA) may be considered to delineate the vascular channels. A pathological biopsy (with sufficient vascular evaluation and necessary protective measures) can also be performed to exclude other rare bone tumors or granulomas.
For arteriovenous malformations (AVM), endovascular embolization is commonly chosen clinically, or staged surgical intervention may be considered based on the lesion’s extent and hemodynamic status:
Because this lesion may lead to changes in bone and soft tissues, and local recovery is required after intervention or surgery, a gradual rehabilitation program under the guidance of professionals is recommended. The following principles may serve as a reference:
Example of FITT-VP Principles:
Disclaimer: This report is based solely on the current imaging data and medical history for preliminary analysis. It does not replace an in-person consultation or the face-to-face diagnostic and treatment advice of a professional physician. If you have any questions or changes in your condition, please contact a specialist or medical institution promptly.
Arteriovenous malformation
