An Infiltrative Angioarchitectural Variant of Arteriovenous Malformation of Temporalis

Abstract

A 19-year-old male reported with a complaint of swelling on the right upper part of the face. The patient noticed it about six months back, which gradually increased in size causing change in his facial profile. There was no associated pain or discomfort, weakness of the facial muscles, abnormal temporomandiblar joint movements, and history of headache or trauma. Also, the patient did not provide any previous medical or any drug history for the same. Examination of the swelling revealed a diffuse enlargement over the right temporal region measuring about 5x4 cm, with no noticeable change in the colour of the skin. On palpation, the swelling was soft, noncompressible, non-tender, distinctly warm and pulsatile. Bruit could be appreciated by auscultation. A provisional diagnosis of vascular malformation was considered.The magnetic resonance image (MRI) revealed a T1W hypointense and T2W mixed intensity lesion involving right temporalis and dentistry section masseter muscles extending from temporal fossa to the infra temporal fossa with flow voids measuring 6.37x4.40x2.81 cms [Table/ Fig-1a]. The neck angiogram showed an evidence of intralesional flow voids supplied by the right ascending pharyngeal branch of external carotid artery and drained by external jugular vein, with cystic spaces [Table/ Fig-1b]. A diagnosis of combined AVM with cavernous angioma of the right temporalis and masseter was made.Complete surgical excision under carotid control via preauricular approach was carried out under general anaesthesia. The entire lesion was found to be located inside the temporalis muscle [Table/ Fig-2]. Elective access osteotomy of the zygomatic arch was done in order to excise the lesion. The surgically excised specimen on gross examination measured about 4x2x1.5cm in dimension, creamish in colour, with an irregular surface [Table/ Fig-3], and firm in consistency with the cut surface showing a few pigmented areas. An Infiltrative Angioarchitectural Variant of Arteriovenous Malformation of Temporalis aBstRaCtVascular anomalies of the head and neck region pose a certain diagnostic and therapeutic paradox. Management of arteriovenous malformations (AVM) is a challenge owing to the presence of abnormal vascular communications and high recurrence. We report a case of a 19-year-old male patient, who presented with diffuse swelling in the right temporal region. Magnetic Resonance Angiography (MRA) suggested it to be an AVM in the temporalis muscle, having afferents in the ascending pharyngeal artery, with cavernous angioma. Surgical excision of the lesion was carried out under carotid control. Histopathology of the excised specimen utilizing special stains confirmed the presence of AVM. An absence of distinct nidus concomitant along with the exuberant proliferation of capillaries between the muscle fibres suggested it be an infiltrative angioarchitectural variant. The present case highlights significance of diagnosing AVM in temporalis muscle which is a rare occurrence in head and neck region. Also, the importance of ruling...