Intraosseous venous drainage anomaly: a case report and the role of the radiologist

A 67-year-old male patient presented at the emergency service with a history of chronic right lower limb pain worsening after low energy trauma. There was a previous history of varices surgery in the right lower limb.

The emergency plain radiography (Fig. 1) showed lytic, poorly defined, non-sclerotic, cortical lesion at the medial aspect of the right tibia. For further evaluation, an MRI of the right leg (Figs. 2, 3) was performed and demonstrated a vessel, in communication with the pretibial varices, that perforated the anterior cortex of the tibia, with a path through the tibial diaphysis to the posterior cortex, where it emerges into the great saphenous vein. The complementary computed tomography (CT) (Fig. 4) indicated the same findings of cortical defect in the tibia. Finally,  the colour Doppler ultrasound (Fig. 5) demonstrated flow through the varicose vein perforating the anterior cortex of the tibia with signs of reflux during the compression manoeuvres. Based on the imaging findings, the diagnosis of pretibial varices with intraosseous venous drainage was confirmed.

Background

Although varicose veins are present in 10%–40% of people aged 30–70 years, the pathogenesis of leg varices remains poorly understood [1, 2, 3]. Increased age, Caucasian race and multiple pregnancies are important risk factors for varix formation [2, 3, 4]. Regardless of these factors, the pathogenesis of varicose veins in the lower extremities is mainly venous valvular dysfunction [1]. Some authors hypothesise that intraosseous venous drainage anomaly may be the cause of varices or deep venous thrombosis and conversely the consequence of venous insufficiency [1,4]. In most cases reported, intraosseous perforating vein incompetence occurred at the draining vein into the tibia, particularly the anterior tibial cortex [1].

Clinical Perspective

Most patients are symptomatic [4, 5]. Clinical presentation depends on the length of evolution and the importance of the reflux. It varies from pretibial varicosities to skin changes, including lipodermatosclerosis and leg ulcers [5].

Imaging Perspective

Imaging can make the diagnosis alone [2, 6]. Plain radiography of the mid tibia demonstrates a round osteolytic defect (2-4.5 mm diameter), perforating the anterior cortex of the bone [5]. This foramen communicates with a proximal, longitudinal radiolucent groove (‘‘double railway track aspect’’) [5]. No worrisome radiographic features like “moth-eaten” or permeative bone destruction, expansion of the medullary canal or soft tissue masses other than varices are present [2, 4].

Colour Doppler ultrasound is usually the first imaging modality and can confirm the presence of dilated veins as well as one varix lying adjacent to a cortical impression defect [1, 2, 3, 4]. However, the dilated intraosseous vein itself cannot be demonstrated because of the inability of the ultrasound waves to penetrate the bony cortex [2].  Furthermore, colour Doppler ultrasound can demonstrate reflux in the varix, which is a sign of valvular incompetence of the intraosseous vein [2].

CT findings of intraosseous perforating vein incompetence consisted of varices in the pretibial soft tissues, a dilated intraosseous nutrient vein, and an enlarged nutrient canal in the affected tibial diaphysis [1, 4]. Multiplanar reconstruction of venous CT scan demonstrates the transtibial route of the venous reflux, originating from the tibial veins, extending through a bony channel to the bone perforator and the varicosities [5].

Magnetic Resonance Imaging (MRI) may be the preferred method to confirm this intraosseous venous drainage anomaly [2, 3]. In some cases, MRI can also depict abnormal signal in the muscles of the symptomatic calf [4]. Moreover, MRI can also be used to rule out other vascular anomalies. Following sclerotherapy, MRI also served as method of monitoring the treatment response [7]. Postcontrast images can be obtained to evaluate for the presence of thrombus [2].

Take-Home Message/Teaching Points

The intraosseous venous drainage anomaly is a rare condition in which the diagnosis can be made by imaging findings alone, avoiding the misdiagnosing and allowing the correct management and treatment.