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Excision of myxoma from Hunters canal( medial thigh)

    Overview

    Learn the Excision of myxoma from Hunters canal( medial thigh) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Excision of myxoma from Hunters canal( medial thigh) surgical procedure.
    In the WHO Classification of Tumours of Soft Tissue and Bone, myxomas are included in the section headed ‘Tumours of uncertain differentiation’. There are four main sub-types: acral fibromyxoma; intramuscular myxoma; juxta-articular myxoma; deep (aggressive) angiomyxoma. Of note myxoma may also occur in the heart or the eye. The most common sub-type encountered by the orthopaedic surgeon is the intramuscular myxoma. Patients present with a lump which may or may not be painful. Ultrasound scanning followed by MRI is recommended for investigation. Most centres dealing with soft tissue and bone tumours would recommend biopsy to confirm the diagnosis. A discussion can then ensue with the patient regarding excision if symptomatic. The main risks of excision include wound problems, infection, damage to adjacent critical structures and recurrence.
    Intramucular myxomas are benign tumours of mesenchymal origin. The incidence is 1 in 1 million with a slight female preponderance of 57%. The typical age range of presentation is 40-70 years. 64% of patients will notice an enlarging mass, with the rest being incidental finding. 55% report that the tumour is painful. The size on presentation ranges from 1-17cm. They can be solitary or multiple. If they are multiple then the patient should be investigated for Mazabraud syndrome which features monostotic or polyostotic fibrous dysplasia.
    It is important to note that if there is any doubt about the diagnosis, a biopsy must be performed to rule out a malignant tumour. There are no reports of malignant transformation of intramuscular myxomas. Therefore if the patient has none or minimal symptoms, non-operative management is recommended. If the patient is symptomatic then excision can be performed. Risks include damage to adjacent critical structures such as large nerve or blood vessels, wound problems, infection and recurrence rates of 30% at a median of 8.5 years.

    Indications

    INDICATIONS
    Incidence and presenting features
    Intramucular myxomas are benign tumours of mesenchymal origin. The incidence is 1 in 1 million with a slight female preponderance of 57%. The typical age range of presentation is 40-70 years. 64% of patients will notice an enlarging mass, with the rest being incidental finding. 55% report that the tumour is painful. The size on presentation ranges from 1-17cm. They can be solitary or multiple. If they are multiple then the patient should be investigated for Mazabraud syndrome which features monostotic or polyostotic fibrous dysplasia.
    Location
    These tumours can occur in any muscle, but the most common site is the quadriceps (65%), hip adductors (<35%), hip abductors (<20%), gastrocnemius and upper arm musculature. If they are multiple and occur in conjunction with fibrous dysplasia, then the tumours are located in the vicinity of the bone lesions and in more than three quarters of cases affect the pelvis and lower limbs.
    Histological features
    Intramuscular myxomas tend to be hypocellular and hypovascular although occasionally the pathologist will report areas of increased cellularity and vascularity. The cells have a stellate shape with small hyperchromatic pyknotic nuclei and scant cytoplasm. In particular there are no cells with evidence of nuclear atypia, mitotic figures or necrosis. The extracellular matrix consists of loose reticulin fibres within an abundant myxoid stroma.
    Management
    It is important to note that if there is any doubt about the diagnosis, a biopsy must be performed to rule out a malignant tumour. There are no reports of malignant transformation of intramuscular myxomas. Therefore if the patient has none or minimal symptoms, non-operative management is recommended. If the patient is symptomatic then excision can be performed. Risks include damage to adjacent critical structures such as large nerve or blood vessels, wound problems, infection and recurrence rates of 30% at a median of 8.5 years.
    Myxoma subtypes
    There are four main subtypes of myxoma that may present to the orthopaedic surgeon. These are the intramuscular myxoma, superficial acral fibromyxoma, juxta-articular myxoma and deep (aggressive) angiomyxoma. Intramuscular myxoma is the most common subtype with the others all having an incidence of less than 1 in 1 million.
    Superficial acral myxoma
    This is an extremely rare tumour with less than 100 cases reported in the literature. It is most commonly located in the subungual and periungual regions of the fingers and toes in adults with a mean age of presentation of 43 years. It is more common in males with a ratio of 2:1. Imaging features are indeterminate due to the small size and rarity of the tumour and therefore diagnosis relies on pathology, usually following an excisional biopsy. Further management depends on patient symptoms although most are cured with an excisional biopsy.
    Juxta-articular myxoma
    These are benign tumours that tend occur in patients aged 20 to 60 years of age. 88% occur adjacent to the knee joint. These tumour arise in the subcutaneous tissues but may infiltrate deeper structures of the adjacent joint. Typical imaging features on the MRI scan include a thickened wall and multiple septae with a hypointense signal to muscle on the T1 sequences. On T2 sequences, the signal is high and hyperintense to surrounding fat (Daluiski A, Seeger LL, Doberneck SA, Finerman GA, Eckardt JJ. A case of juxta-articular myxoma of the knee. Skeletal Radiol. 1995 Jul;24(5):389-91.). As per intramuscular myxoma, a biopsy is required to exclude malignancy and surgery is offered if the patient is symptomatic.
    Deep (aggressive) angiomyxoma
    These tumours are very rare with only about 250 cases reported in the literature. It most commonly presents in women of reproductive age with the pelvis being the most affected location. These tumours are usually slow growing but can be infiltrative making excision difficult. Prior to consideration of surgery, a biopsy is mandatory to exclude a malinancy.
    SYMPTOMS & EXAMINATION
    64% of patients will present having noticed a lump or diffuse swelling. 55% will report pain in the lump which may be exertional or present at rest.
    Depending on the location of the myxoma, the tumour may be visible very obvious and easily palpable e.g. if arising in rectus femoris, or there may be a more subtle swelling, with the tumour not palpable e.g. if arising in the hip adductors. Tenderness will vary and there are rarely any neurovascular deficits.
    IMAGING
    Ultrasound scanning will typically be reported as showing an indeterminate solid mass with internal vascularity.
    MRI often features hyperintense signal on the T2 sequence. MRI is also essential to assess proximity to critical structures. The differential diagnoses include chronic haematoma, peripheral nerve sheath tumours, myxofibrosarcoma, lymphangioma, myxoid liposarcoma, myxoid malignant fibrous histiocytoma, extraskeletal myxoid chondrosarcoma, botyroid rhabdomyosarcoma.
    ALTERNATIVE OPERATIVE TREATMENT
    If the myxoma is symptomatic, intra-lesional excision should be discussed with the patient. Symptomatic lesions are often large, painful and tend to gradually increase in size increasing the risks of surgical complications if excision is not undertaken for a prolonged period of time.
    NON-OPERATIVE MANAGEMENT
    There are no reports of malignant transformation, so if the myxoma is asymptomatic, then the patient can be advised to monitor it and request review if they are concerned in the future.
    It is important to reiterate that because malignant tumours are in the differential diagnosis on imaging, a biopsy must be undertaken to ensure that the tumour is definitely a myxoma.
    CONTRAINDICATIONS
    Relative contraindications to excision include myxomas adjacent to critical structures which would be at high risk of damage during excision.


    Setup

    GA. No prophylactic antibiotics required.
    Double alcoholic skin preparation of the whole leg including the foot. Draping to exclude the lower leg leaving the thigh exposed.
    VTE prohpylaxis: Flowtron on the contra-lateral lower leg intra-operatively. Early mobilisation post-operatively. 6 weeks TED stockings. LMWH during the hospital admission and for 10 days post-operatively.

    Operation

    The axial MRI demonstrates the mxyoma in the adductor compartment of the thigh arising in adductor longus(1).
    The tumour therefore lies in the subsartorial canal. This canal is also known as the adductor canal or Hunter’s canal. The contents of the subsartorial canal include the superficial femoral artery and vein and branches of the femoral nerve. The boundaries of the canal are: sartorius anteromedially; adductor longus and magnus posteriorly; vastus medius laterally. In this case, the tumour has arisen in adductor longus. Vastus intermedius lies laterally and adductor magnus is posterior and medial to the tumour.
    The axial slices are particularly important to assess proximity of the tumour to the superficial femoral artery and vein. In this case the vessels are very close to the superior aspect of the tumour and therefore the surgeon needs to take care when dissecting into this area.

    This coronal MRI demonstrates the intramuscular myxoma in the adductor compartment of the thigh. These slices can be used to visualise the femoral vessels as they run along the supero-medial aspect of the tumour.

    This sagittal image demonstrates the intramuscular myxoma in the adductor compartment. These slices are useful to assess the course of the femoral vessels over the superior aspect of the tumour.

    The patient is placed supine with the right hip abducted and externally rotated to facilitate a medial approach to the thigh.On the contralateral leg, a flowtron is placed to help reduce the risk of deep venous thrombosis.

    Application of the skin preparation using alcoholic chlorhexidine. It is important to include the foot in order to minimise the risk of infection.

    The leg is draped free to allow for positioning with the hip flexed and abducted. The skin is marked to guide the incision.

    The skin incision is performed at the mid-thigh and given the tumour is 5cm in its maximum dimension the skin incision needs to be 8cm long, extended as required to safely remove it from the adjacent critical structures.If the tumour is easily palpable then the incision can be centred over the mass. Most, as in this case are not easily palpable and therefore in order to centre the incision appropriately, the MRI should be scrutinised. In this case the tumour is in adductor longus which arises from the inferior pubic ramus and distally the fibres extend into the adductor canal at the junction of the proximal and middle thirds of the thigh. Additional measurements can be made on the MRI from the groin crease to the centre of the tumour to aid placement of the skin incision. In order to place the incision accurately in the anterior to posterior plane, the MRI sagittal sequences will allow measurements- in this case the incision was placed 6cm posterior to the anterior thigh skin surface. Note also the vertical skin markings which will help facilitate accurate skin closure at the conclusion of the operation. A further option to mark up the skin incision would be to utilise an ultrasound machine to visualise the tumour.

    Diathermy is used to incise the subcutaneous fat down to the fascial layer.

    Subcutaneous vein tributaries into the long saphenous vein are identified in the fat layer.These are small veins that run perpendicularly or obliquely into the long saphenous vein. They can usually be ligated with diathermy although in some patients with varicosities they may be larger and engorged and require formal ligation with hand ties.

    The subcutaneous veins are mobilised.

    Diathermy is used to coagulate the subcutaneous veins.

    The fascia is incised and the long saphenous vein mobilised.At this stage the myxoma is palpable anterior to the course of the vein. The saphenous vein is therefor retracted posteriorly and the proximal end of the fascia is carefully incised with a scalpel and then split distally with dissecting scissors. If the vein is damaged then it can be ligated with hand ties. In most patients this will not cause any symptomatic concerns.

    Sartorius has been identified and will be retracted anteriorly. It is important to note that the superficial femoral vessels lie under sartorius in the subsartorial canal.
    Sartorius is identifiable at this level of the thigh because it is the most superficial muscle under the fascia anterior to the palpalble myxoma.
    It is also narrow from anterior to posterior and easily mobilised with finger dissection. At its anterior edge lies rectus femoris, posteriorly is adductor longus, in this case with the palpable myxoma. Gracilis lies just posterior to adductor longus.
    As mentioned in the imaging section, sartorius forms one of the boundaries of the adductor (subsartorial) canal. The contents of the canal include the superficial femoral artery and vein and branches of the femoral nerve. The boundaries of the canal are: sartorius anteromedially; adductor longus and magnus posteriorly; vastus medius laterally.


    Once the sartorius is mobilised, a self retaining retractor can be carefully placed into the wound bed to retract sartorius anteriorly and gracilis posteriorly.Sartorius is mobilised with finger dissection in order to visualise the contents of the subsartorial canal, which include the superficial femoral artery and vein.

    Further dissection into the subsartorial canal is made using McIndoe’s dissecting scissors and Debakey forceps in order to minimise trauma to neurovascular structures.

    The surgeon can identify the superficial femoral artery by palpation followed by formal dissection of the vessels.

    The superficial femoral vessels (1)are visible deep to sartorius ready for mobilisation. The key to safely delivering the tumour is to ensure these vessels are adequately mobilised. Typically there are two to three vein tributaries and a similar number of arterial branches.

    The surgeon should use a Debaky’s forceps and McIndoe’s dissecting scissors to mobilise and identify the branches and tributaries that require ligation of the superficial femoral vessels.The superficial femoral vessels are mobilised to reduce the risk of damage to them when the tumour is delivered.

    Deeper traversing vessels are ligated to help mobilise the superficial femoral vessels. Ligation should be performed with 2.0 Vicryl hand ties in continuity i.e. the ties are placed around the vessels before they are cut. This allows for better control and less bleeding.

    The tumour is palpated in the adductor longus muscle.At this stage it is easy to palpate but the tumour capsule is adherent to the surrounding muscle.

    The tumour is carefully mobilised into the wound bed by using blunt dissection to tease the muscle fibres off the tumour capsule.Sharp dissection should be avoided because breach of the tumour capsule may lead to recurrence of the tumour.

    The tumour is dissected free and sent to the pathology laboratory fresh.
    The tumour will have been biopsied prior to formal excision and therefore there are no reports of a change in pathological diagnosis. Note the superficial femoral artery at the tip of the surgeon’s forceps and inferior to the artery the vein is visible. The bulbous structure in the vein is a valve.

    Following delivery of the tumour, the superficial femoral vessels are inspected to ensure there is no bleeding or significant damage and closure follows.
    The fascia is closed with a 2.0 Vicryl absorbable sutures. It is important to use interrupted sutures to avoid failure of this layer post-operatively which can lead to muscle herniation. Closure is completed with a continuous 2.0 Vicryl dermal suture followed by a 3.0 Monocryl subcuticular continuous suture for the skin.

    Post Operative

    The patient is mobilised as soon as they have recovered from the GA under supervision of a physiotherapist. VTE prophylaxis: 6 weeks TED stockings. LMWH during the hospital admission and for 10 days post-operatively.
    Maintain the pressure dressing until the wound review at 10-14 days.
    Outpatient follow up clinic in 10-14 days for the wound check and to confirm the pathology result is the same as the biopsy.

    Recommended Reading

    Nielsen G et al. Intramuscular myxoma: a clinicopathologic study of 51 cases with emphasis on hypercellular and hypervascular variants. Am J Surg Pathol. 1998 Oct;22(10):1222-7. doi: 10.1097/00000478-199810000-00007.
    This is an important paper that describes the histological features of intramuscular myxomas. Occasionally there are hypercellular areas without and it is important that an erroneous diagnosis of sarcoma is not made. In this series of 51 cases, there were no recurrences or evidence of metastatic behaviour although the follow-up ranged from 3-108 months.
    Luna et al. Magnetic resonance imaging of intramuscular myxoma with histological comparison and a review of the literature. Skeletal Radiol. 2005 Jan;34(1):19-28. doi: 10.1007/s00256-004-0848-9. Epub 2004 Oct 22.
    This paper describes the MRI findings of 17 cases of intramuscular myxomas in detail. All were hyperintense on T2 weighted sequences. Most tumours has a pseudocapsule that could be identified on the MRI and a few had additional intratumoural cysts.
    Allen. Myxoma is not a single entity: a review of the concept of myxoma. Ann Diagn Pathol. 2000 Apr;4(2):99-123. doi: 10.1016/s1092-9134(00)90019-4.
    This paper comprehensively covers the different types of myxoma focussing on the five entities regarded as mainstream soft tissue myxomas (namely, intramuscular myxoma, juxta-articular myxoma, superficial angiomyxoma, aggressive angiomyxoma, and myxoid neurothekeoma [myxoma of nerve sheath]). It is these five myxoma types that the orthopaedic surgeon needs to be aware of.

    Reference

    • orthoracle.com

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