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Soft Tissue |
General Considerations |
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General comments on skin specimen evaluation:
- Always read the requisition form before touching the specimen. Often minimal information is provided, and you may need to contact the submitting physician with questions or check the computer for prior biopsy results before proceeding.
- Excisions for melanoma need particular care (refer to Melanoma: Points of Consideration, below). Usually the entire specimen is submitted (unless very large).
- If there is a suspicion of infection, you should request unstained slides x 5 to be cut at the time of routine sectioning, since skin specimens are often small and can be cut away easily. We may decide to use these for special stains after examining the H&E sections. If the specimen arrives in saline only (i.e. no fixative), you may be asked to cut off a piece of tissue and submit it for culture to microbiology. This requires sterile technique.
- Margins for tumor should be inked, whereas margins in non-tumor cases do not need to be inked. When in doubt, go ahead and ink the margins. Ink both peripheral (cut edge of superficial skin) and deep margins.
- Count the number of pieces received and try to determine the biopsy type (curettage, shave, punch, excisional). Describe the shape of the piece(s) (round, elliptical, square, irregular). Measure the skin in three dimensions, specifying which two are surface dimensions and which is the excisional depth. Mention if subcutaneous fat is present.
- Describe the color of the uninvolved skin and any lesions which may be present (especially the presence or absence of pigmentation). Try to use nomenclature of dermatology. Measure the lesion(s) and lesional distance from the nearest margin (specify which margin this is, if the specimen is oriented).
- Very large, superficial (i.e. thin) excisions may be pinned out flat and allowed to fix for a few hours before sectioning.
- Use a sharp, clean blade and a clean board. Carry-over from a previous case may be difficult to prove when dealing with small specimens.
- Skin specimens should always be sectioned and embedded “on edge”. This means that your knife blade should cut through all levels of the skin (epidermis, dermis, and subcutis), traversing the specimen perpendicular to the skin (epidermal) surface. This plane of sectioning should be placed face down in the cassette. Cutting the tissue in this way allows us to see all layers of the tissue, from the epidermal surface through to the deep aspect, in a single histologic section.
- Examine the cut surface of the specimen and describe it. If you see tumor, measure the depth of invasion (tumor depth) and indicate which compartments are involved (e.g. deep dermis).
- Submit all of the tissue, unless very large or if normal tissue removed as a part of plastic surgery.
- Don’t be afraid to ask questions!
- Macule: flat, circumscribed, usually pigmented lesion
- Papule: elevated solid area < 5 mm
- Nodule: elevated solid area > 5 mm
- Plaque: elevated solid area with a flat top
- Blister: fluid-filled area
- vesicle: < 5 mm
- bulla: > 5 mm
- Pustule: pus-filled area
Melanoma: Points of consideration:
- When melanoma is clinically suspected or has been previously diagnosed, excisional biopsies are preferred because they allow for microscopic evaluation of the entire lesion, including the base and peripheral borders.
- Frozen sections on melanocytic lesions should be avoided. The frozen section procedure consumes lesional tissue and causes distortion of tumor remaining in the permanent sections, which may limit diagnostic accuracy.
- When examining the specimen, pay close attention to the presence or absence of satellite nodules (especially in excisional specimens) and pigmentation; if a pigmented lesion is present, describe if the pigment is diffuse or patchy/focal.
- It is usually appropriate to submit the entire specimen, even if no tumor is identified on macroscopic examination. In the event that a large, bulky tumor is submitted, it may be sufficient to submit representative sections including the closest margins and deepest points of invasion; in such a situation, the attending pathologist should be consulted.
- If lymphadenectomy has also been performed, refer to the applicable (i.e. sentinel vs. regional) lymph node protocol.