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    Nail

    Background

    Finger and toe nails are occasionally received in the histology laboratory. The main indications for nail biopsy are inflammatory disorders localised to the nail, nail tumours and longitudinal melanonychia. Distal nail plate samples (nail clippings) can also be used for diagnosis of onychomycosis (fungal infections).1-4

    Refer also to the skin protocol for orientated nail tumour excision specimens.


    Record the patient identifying information and any clinical information supplied together with the specimen description as designated on the container. See overview page for more detail on identification principles.

    • No
      • Non-routine fixation (not formalin), describe
    • Yes
      • Special studies required, describe
      • Ensure samples are taken prior to fixation (e.g. microbiology, immunofluorescence)

    See general information for more detail on specimen handling procedures.

    Photograph the intact specimen, if required.

    Inspect the specimen and dictate a macroscopic description.


    External Inspection

    Describe the following features of the specimen:

    Procedure

    Describe as stated by the clinician.

    • Distal nail plate samples (clippings)
    • Nail bed biopsy
    • Nail matrix biopsy
    • Longitudinal nail biopsy
    • Subungual tumour biopsy

    Anatomical components and specimen dimensions (mm)

    Describe and measure the anatomical components present.

    • Number of pieces
    • Entire specimen or aggregate dimensions if multiple pieces
    • Nail in three dimensions (if present)

    Lesion

    • Absent
    • Present
    • Number; if more than one lesion, designate and describe each separately
    • Describe the presence of any pigment alterations apparent in the nail macroscopically

    Lesion size (mm)

    • In three dimensions
    • Lesion description
    • Describe
    • Distance from margins (mm)

    Lesion description

    • Describe
    • Distance from margins (mm)

    Dissection

    • Nail clippings require no dissection.
    • Punch biopsies are bisected and submitted in their entirety.
    • Longitudinal nail bed biopsies and subungual tumours should be sectioned at 3-4mm intervals, usually parallel to the longitudinal axis of the nail starting from the central part of the nail to the lateral (skin) aspect.

    Internal Inspection

    Not required.


    Processing

    • Nail specimens may be softened after fixation (e.g. with 10% potassium hydroxide) and before processing. 3 Alternatively or additionally, a softener (e.g. 10% potassium hydroxide, 4% aqueous phenol, Tween® 40)3 or hair removal product (e.g. Nair™ or Veet®) may be applied to the surface of paraffin blocks before sectioning. Submit entire specimen whole for processing.
    • Small fragments and friable tissue should be transferred directly into cassettes for processing. Lens paper, biopsy pads or similar are required to prevent loss of tissue during processing.
    • Submit all sections of nail bed biopsies and subungual tumour specimens in sequential order, sectioned to demonstrate maximum depth of lesion and relationship to margins.
    • Routine special staining with periodic acid Schiff’s diastase (PAS-D) is useful on nail specimens. Perl’s and Masson Fontana stains may assist in the diagnosis of pigmented lesions.

    Record details of each cassette.

    An illustrated block key similar to the one provided may be useful.

    Block allocation key

    Cassette id
    Site
    No. of pieces
     A-B
     Nail biopsy
     

     

    Acknowledgements

    Dr Craig James for his contribution in reviewing and editing this protocol.


    References

    1. Lester SC (ed). Manual of Surgical Pathology, Saunders Elsevier, Philadelphia, 2010.
    2. Lewin K, DeWit SA and Lawson R. Softening techniques for nail biopsies. Arch Dermatol 1973;107(2):223-224.
    3. Calonje JE, Brenn T, Lazar A, McKee P. McKee’s Pathology of the Skin. Elsevier Saunders, Oxford, 2011.

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      Nail 1

      Fingernail with anatomical landmarks and biopsy sites

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      27-Mar-2019
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