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Molecular diagnostics laboratory - skin tumour unit

Referral centre for primary cutaneous lymphoma and malignant melanoma


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  • Skin Tumour Unit molecular diagnostics laboratory
    St John's Institute of Dermatology
    9th floor
    Tower Wing
    Guy's Hospital
    London SE1 9RT

  • Tel (patient related queries):       020 7188 6375

    Tel (laboratory related queries):
    020 7188 8081 or bleep 1997

    Fax: 020 7188 8050

    Email contacts: 

    Head of laboratory:

    All Laboratory staff:

    Opening times: Monday - Friday, 9am - 5pm


The molecular diagnostics laboratory forms part of the skin tumour unit. We are a tertiary referral centre for all forms of primary cutaneous lymphoma and malignant melanoma and have a strong international reputation for clinical excellence and research.

The unit offers a wide range of treatments for all stages of disease including ECP, PUVA and TSEBT. We also undertake clinical trials for novel therapies.

The laboratory offers a referral service for comparative analysis of T cell (TCR) and B cell (IgH) clonality assessment in lymphoproliferative disorders.

Translational research is fundamental to the laboratory and we are continually working towards introducing new molecular tests to aid in the diagnosis, prognosis and treatment of cutaneous lymphoma. Please email Dr Tracey Mitchell using the email address at the top of this page for more information.


  • Referrals

    Please contact us by telephone or email in advance of sending any specimens so we know to expect the sample. We will also provide detailed information of where the samples should be sent.

    We accept referrals from all NHS and private consultant dermatologists and pathologists from the UK and abroad.

  • Assay service

    Clonal TCR and IgH gene rearrangements can be performed on DNA extracted from skin biopsies and peripheral blood. Lymph nodes and bone marrow aspirates can also be analysed. T-cell clonality studies are performed on extracted DNA, followed by PCR/SSCP analysis for TCR gamma gene rearrangements (V gene families I – IV and pseudogenes if appropriate).

    Any samples that fail to amplify will be tested with control primers for cyclophilin to confirm DNA integrity. Each assay will be performed with the appropriate controls. IgH gene rearrangement studies are performed on extracted DNA and analysed by PCR/heteroduplex analysis using the Biomed II protocol, appropriate controls are included.

  • Specimen preparation

    Skin biopsies

    Please provide an ellipse biopsy of the lesion, cut through into the fat layer. The biopsy should be at least 5 mm in diameter, and placed dry into a pot.


    Please provide two EDTA tubes (10-15 ml of whole blood).

    FFPE tissue

    Please provide cut 10-15 sections (curls), 10µm thick, dry in a sealed and labelled 1.5ml Eppendorf tube.

    We are able to analyse DNA extracted from paraffin embedded tissue but the quality and quantity of the DNA extracted depends on the size of the biopsy and the fixation method. Punch biopsies are often difficult to analyse due to the small size. 

    All fresh samples should be received within 24 hours after collection.

  • Turnaround time and reporting of results

    Reports will be issued within 15 working days from receipt of the sample.

    Reports will be sent via email to the requesting clinician. Information and results will not be sent to patients.

  • Costs

    Please contact Dr Tracey Mitchell on 020 7188 8075 for advice or further information.