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ARTERIO-VENOUS MALFORMATION OF VASTUS MEDIALIS MUSCLE

Dharmesh J Balsarkar*, Mohan Joshi**, RR Satoskar**
*Lecturer; **Professor, Dept. of Surgery, LTMMC and LTMGH.

INTRODUCTION

Vascular malformations of the extremities are grouped into three categories : arteriovenous malformations, haemangiomas, and purely venous malformations. [1] Vascular malformations present a notoriously difficult therapeutic challenge and hence management requires detailed knowledge of the location and extent of the lesion. [1] Angiography is the principal method of evaluation, but the role of MRI in evaluating venous malformation is superseeding angiography since more clear information regarding the lesion could be obtained by a relatively noninvasive procedure. [1] We describe here a successfully managed case of arteriovenous malformation of left vastus medialis muscle.

CASE REPORT

An 18 year old male presented with incidentally detected swelling over medial aspect of left thigh since four months. No other positive history was noted. On examination, a 3 x 3 cm. firm ill-defined swelling arising from the left vastus medialis was noted. Investigations done revealed a normal haemogram. Plain X-ray of left thigh was normal. A CT scan of left thigh was performed which showed a well defined mass with multiple septations, necrotic areas and septal and peripheral enhancement, measuring 3.3 x 4.6 cm. involving the left vastus medialis in the mid and lower thigh region. The mass did not extend into the inter-muscular plane and the underlying bone was normal. The most probable diagnosis was neoplasm or chronic abscess (Fig. 1). Hence an MRI scan was performed which showed a mass lesion within the left vastus medialis in the middle third extending over a distance of approximately 10 cm. The lesion was predominantly hyperintense on all pulse sequence, with few serpigeneous signal voids suggestive of vessels within the lesion (Fig. 2). A few punctate hypointensities on the GRASS images within the lesion represented either paramagnetic substances/calcium/fibrous tissue (Fig. 3). The most likely MRI diagnosis of haemangioma was made, but the possibility of neoplasm like soft tissue sarcoma was to be considered.

CT scan of left thigh showing a well defined mass involving left vastus medialis
Fig 1
CT scan of left thigh showing a well defined mass involving left vastus medialis muscle.


MRI showing mass lesion in left vastus medialis muscle with exact extension of lesion.
Fig 2
MRI showing mass lesion in left vastus medialis muscle with exact extension of lesion.


Patient underwent surgery, where a 6 x 4 x 2 cm. firm, well encapsulated lesion within the vastus medialis was removed after ligation of feeding vessel at the superior aspect (Fig. 4). Histopathology of the swelling was reported as arterio-venous malformation.

GRASS image on MRI scan showing punctate hypointensities
Fig 3
GRASS image on MRI scan showing punctate hypointensities

 

Cut open section of specimen.
Fig 4
Cut open section of specimen.


DISCUSSION

AVMís are congenital anomalies resulting from faulty development of arterial, capillary, venous or lymphatic structures or any combination thereof. [2] The lesions are thought to be present since birth and do not represent neoplasm. [2] They can remain dormant for many years and many go undetected in life and there is no apparent sexual predominance. [2] Detection results from observation of skin discolouration, secondary effect of lesion on adjacent organ or as a mass, [2] as was seen in presented patient. Vascular malformations can occur anywhere in the body and extremities are the commonly affected sites. [2] Majority lesions occur as isolated cases confined to one anatomic location, as was seen in the presented patient, but multiple lesions have been reported in some cases. [2] AVMís that are accessible to physical examination are usually firm, spongy and non-compressible; [2] presented patient had a firm mass.

Routine laboratory investigations in these patients are unrevealing. [2] Angiography has been used primarily to delineate the extent of AVMís however, it has limitations like inability to depict the relationship to specific muscle group, fascial planes, tendons and nerves and also the extension into bone cannot be detected. Large AVMís on angiography may be seen as a "white cut" of the limb, making interpretation difficult or impossible. [2]

CT scan gives the above information but CT scan is essentially restricted to transverse images. [2] MRI provides a graphic depiction of extent and complexity of the lesion in a manner similar to that seen at surgery; [2] presented patients MRI gave similar information.

Asymptomatic lesions do not require treatment once the nature of the mass has been confirmed. [2] Absolute indications for treatment include haemorrhage, secondary ischaemic complications and congestive heart failure from arteriovenous shunting. [2] Relative indications for surgery include pain, functional impairment and cosmetic deformity. [2]

Patients who have symptomatic lesions judged to be resectable by careful preoperative evaluation should undergo resection because complete removal provides the best chance for cure. [2]

REFERENCES

    1. Cohen JM, Weinreb JC, Redman HC. Arteriovenous malformations of the extremities : MR imaging. Radiology 1986; 158 : 475.
    2. Rosen RJ, Riles TS, Berenstein A. Congenital vascular malformations. In Robert B Rutherford (eds) : Vascular surgery. WB Saunders Company. 4th edn. II : 1218-32.

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