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Muscle and Skin Biopsy

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Purpose

To provide practical guidelines for obtaining muscle +/- skin biopsies

Referral process

Referrals should be made from the Requesting team to the Surgical team on call. Where possible, all muscle biopsies should be done in normal working hours. THIS MEANS THE MUSCLE BIOPSY MUST BE IN THE LAB BEFORE 4PM.

  • The surgical registrar should consent the patient/parents of the patient. History and clinical findings and indication for muscle biopsy should be reviewed.
  • Often a skin biopsy is also needed. Please check with the requesting team that this has not been missed. 
  • Risks associated with the procedure include: bleeding from the biopsy site, infection, scarring, limb numbness or inadequate biopsy. It is important to be aware that some underlying conditions which are routinely investigated by muscle biopsy, may be associated with an increased risk of significant anaesthetic complications including malignant hyperthermia (MH), anaesthesia induced rhabdomyolysis and propofol infusion syndrome. Schedule the patient first on the list if risk factors for MH exist - liaise with the paediatric metabolic or neurology consultant. Risks associated with a skin biopsy are: infection, bleeding, poor growth of the skin fibroblast cells. 

Selection of an appropriate biopsy site

The most common site for biopsy is vastus lateralis, at the anterolateral thigh. Several factors have to be considered when selecting a site to biopsy. In general, it should be based on the distribution of muscle weakness. Alternative sites include the gastrocnemius, biceps or deltoid. In patients with a more distal pattern of disease, a more distal limb muscle may be selected. However, even in this group, a proximal muscle biopsy is usually adequate for diagnosis of the underlying pathological process. In all metabolic patients, where possible, the vastus lateralis should be biopsied as reference ranges for biochemical studies are based on this site. Take care to avoid injury to regional nerves.

Preparation

PRIOR to starting the case the team requesting the biopsy should be contacted to confirm sample preparation and ensure:

  1. The correct samples will be taken
  2. The forms are written (use an orange, urgent, fresh specimen form. The form should have the details of the consultant requesting the biopsy including their phone number, the reason for the biopsy and what is needed - normally this will be histology, histochemistry, electron microscopy (EM) and immediate freezing for mitochondrial respiratory chain enzyme (RCE) analysis)
  3. The histology lab is notified (discuss with Natasha Caldwell, section leader, or one of the team at the cut-up station on ext 22090. If after hours, call the histopathologist on call via the switchboard)
  4. Someone from the requesting team is available to transport the urgent specimen to the lab and the theatre has that persons number

If the sample is for mitochondrial studies, a medical member of the requesting team MUST be in theatre ready to receive the FRESH muscle biopsy. Please note that the Gold Standard for enzyme testing in muscle is to put a piece of the specimen into liquid nitrogen in theatre. This is not currently available at Starship hospital so the medical member of the team must RUN THE SAMPLE TO SPECIMEN RECEPTION LAB PLUS. Tell them it is super urgent and call ext 22090 to let them know it is there.

Performing the open muscle biopsy

  • General anaesthetic
  • Prep and drape the selected site over an appropriate muscle e.g. anterolateral femur where the vastus lateralis is closest to skin 
  • 2-3 cm longitudinal skin incision with a scalpel 
  • Dissection in layers through subcutaneous tissues until fascia lata is exposed
  • Place a West self retaining retractor
  • Longitudinal incision in fascia lata
  • Place two 4.0 absorbable monofilament stay sutures at either end of a 15mm x 7mm x 7mm sample
  • Excise the muscle biopsy with a sharp scalpel or sharp iris scissors, using the stay sutures for retraction. DO NOT use diathermy as this will damage the specimen. 
  • Check the biopsy is adequate: There is not extensive fascia or fat, the sample is adequate size Place the biopsy onto SALINE MOISTENED GAUZE and hand off to the referral team member for immediate transport 
  • Check for bleeding and use bipolar or monopolar diathermy for haemostasis 
  • Infiltrate the wound with local anaesthetic and close in layers with 3/0 or 4/0 absorbable monofilament to fascia and 4/0 or 5/0 absorbable subcuticular sutures to skin.
  • Dressing as per surgeon's preference. 

Skin biopsy

To perform a skin biopsy

  • The surgical team should consent for this
  • Take skin from the incision site (at least 3mm x 3mm is all that is needed)
  • Place the skin into TISSUE TRANSPORT MEDIUM (obtained from the Cytogenetics department). If this is not available it can be put into sterile normal saline. The skin must not be frozen
  • The form should be filled in by the requesting team. A standard lab form can be used. It should say: 'Skin for fibroblast culture and storage -  to Cytogenetics'. Put the requesting consultants name and phone number on the form.
  • There is no urgency with this sample. Once the biopsy is in transport medium it should be sent to LabPlus Cytogenetics.

If a skin biopsy is to be performed at the bedside by one of the medical team, do the following:

  • Obtain consent from parents (and patient if appropriate). Complications: bleeding, infection, the skin cells may not grow
  • Obtain culture medium from the Cytogenetics Lab, Lap Plus. The culture medium should be stored at -4C. In an emergency use sterile normal saline
  • Get your equipment ready. You will need: a dressing pack, chlorhexidine, gloves, diabetic syringe for lignocaine, scalpel blade, needle, forceps, gauze, steristrips, a small dressing and the medium. Obtain a 3-4mm punch biopsy. These can be found on ward 26A
  • Select a site. It is traditional to use the forearm but for smaller children the posterior axillary fold is often easier. The child lies on their side with the uppermost arm pulled forward 
  • Infiltrate with 1% lignocaine
  • Use a skin punch to cut a disc of skin. This will usually detach cleanly if the punch is twisted, but if not lift the biopsy with a sterile venipuncture needle or cut a small amount of dermis with a scalpel blade
  • Put the biopsy into culture medium and apply pressure for two minutes to the site with a dressing
  • Place steristrips over the incision and cover with a small waterproof dressing. This can be removed in a few days.
  • Send the sample to Cytogenetics, Lab Plus for fibroblast culture. It must not be frozen or put in the fridge. Label the sample with the consultants name and, if appropriate, the test required. They will contact the consultant for further instructions.

Post-op advice to the patient

  • Leave the dressing on for 3-4 days
  • Review the wound with your GP, or with the operating team if still in hospital, in a few days.
  • If asked about results, surgical team should advise that the requesting team will make arrangements to see them to discuss results and that these can take up to 3 months to come back

Post op responsibility of the requesting team

  • The deliverer of the sample must ensure everything has arrived and is being processed in the lab
  • The deliverer must notify the consultant in charge of the patients, if not done so already, that the biopsy has been done. 
  • The responsible consultant must write a letter to Dr David Thorburn, Murdoch Institute, 50 Flemington Rd, Parkville VIC 3052 describing the case, the biochemistry results, why the sample has been taken and if possible, the histology results. The letter should be cc'd to Natasha Caldwell, Section leader, Histopathology and Dr Clinton Turner, histopathologist or Dr Jane Evans, histopathologist, LabPlus
  • The responsible consultant must write a letter to the referral lab if enzyme or other testing of the skin is needed 

Out of hours protocol: Lab details

  • All effort should be made to perform samples in working hours. This is means it is received in the laboratory before 4PM.
  • If a patient is very unwell and the biopsy needs to be performed out of hours the main team affected will be the histopathology team. The main issue with doing out of hours biopsies is ensuring adequate tissue handling.
  • If this is needed the following should occur: contact the histopathologist on call via the switchboard and let them know what is needed and when the sample will be taken. They are there to cover the after hours service and it has been agreed with LabPlus that they will come in to process the samples. The skin biopsy should be put into saline and cytogenetics notified of the sample in working hours.

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Document Control

  • Date last published: 01 August 2014
  • Document type: Clinical Guideline
  • Services responsible: Metabolic, Paediatric Surgery
  • Author(s): James Hamill, Clinton Turner, Emma Glamuzina, Marilyn Wong, Tim Bradnock
  • Editor: Greg Williams
  • Review frequency: 2 years

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