Presentation
Increased size of left thigh, evaluate with MRI. The patient later developed mild pain when walking.
Patient Data
Well-defined mass in the left biceps femoris long head and to a lesser extent semimembranosus and semitendinosus muscles, measuring 3,3 x 5,0 x 10,5 cm (AP x T x CC). Mildly elevated T2WI and T1WI signal relative to skeletal muscle with hyperenhancement and a few internal flow voids.
Pulsatile hypervascular arterial flow in the mass on ultrasound.
Hypervascular intramuscular mass involving the muscles described above with numerous tortuous vessels, enlargement mainly of the left deep femoral artery and early venous enhancement suggestive of arteriovenous shunting. However, the presence of a discrete mass makes an arteriovenous malformation unlikely.
Surgical biopsy was suggestive of an intramuscular hemangioma, but clinical behavior was suggestive of an arteriovenous malformation, so the multidisciplinary consensus was to perform preoperative embolization and subsequent surgical resection of the long head of the biceps femoris muscle in order to have a better pathological specimen.
Embolization of the distal enlarged left deep femoral artery and a branch of the superficial femoral artery with gelatin sponge particles.
The patient underwent resection of the long head of his left biceps femoris muscle. Surgical biopsy and later surgical excisional pathology were reviewed by an expert vascular pathologist (Michel Wassef, Paris), concluding on both specimens a diagnosis of intramuscular hemangioma, GLUT-1 negative.
The residual parts of the mass in the semimembranosus and semitendinosus muscles have minimally increased in size and remain hyperenhancing, but the evaluation is limited seeing as those muscles have also hypertrophied after the resection of the long head of the biceps femoris muscle. No more early venous enhancement.
Since the follow-up CT scan 14 months prior, no change in residual mass size. The semimembranosus portion is less enhancing than the semitendinosus portion, but signal characteristics are otherwise rather unchanged.
Case Discussion
After 8 years of total follow-up, the patient was asymptomatic with stable mass size on subsequent ultrasounds.
Intramuscular hemangiomas are rare vascular anomalies, currently (at the time of writing in 2022) in the "Provisionally unclassified vascular anomalies" of the ISSVA classification of vascular anomalies. They should not be confused with infantile hemangiomas which are much more common and stain GLUT-1 positive, nor with intramuscular venous malformations which are sometimes referred to inappropriately as "hemangiomas".
Growth is generally proportional to somatic growth, or very slowly progressive over time. Some cases can mimic arteriovenous malformations (AVMs) on Doppler because of large arterialized vessels, but resistive index is generally high and there is usually no significant arteriovenous shunting, in addition to there always being a discrete mass which should not be seen in AVMs. In this case, arteriovenous shunting was a confounding factor that led to obtaining a larger surgical specimen to confirm the diagnosis.
Case courtesy of Dr Laurent Guibaud.