Specimen Handling

Fragments, non-orientated:

• usually multiple fragments, free floating in fixative, non-orientated.

• place in cassette between foam insert pads or loosely wrap in moist filter paper.

• insert levels label.

• align in the block at the embedding stage as this facilitates microscopic assessment and fragments are not missed.

• separate specimens: use separate cassettes and site identification labels appropriate to the request form information.

• cut through multiple levels.

Fragments, orientated:

• this allows better assessment of mucosal architecture and site distribution of lesions, e.g., colonic strip biopsy in chronic inflammatory bowel disease.

• filter paper: count the fragments and note any that have detached. Process intact between foam insert pads or covered by moist filter paper to preserve orientation for embedding and cutting through multiple levels.

• polycarbonate strip (Figure 1): the endoscopist allows a 2-4 minute period of air drying prior to formalin fixation, ensuring adherence of the mucosal fragments to the strip which is designated according to a pre-agreed protocol, e.g., the cut pointed end is distal or anorectal. Strict alignment of the fragments on the strip by the clinician is essential as it is embedded intact and on its edge for cutting to allow representation of all the fragments at the same level in the block. Count the fragments and cut through multiple levels.

Polyps (Figure 2):

• non-orientated fragments: these are handled as indicated above.

• snare specimens:

- <1 cm diameter - bisect vertically down through the stalk/base and embed both cut surfaces face down. Cut through multiple levels.

- > 1 cm diameter - obtain a central, vertical mid-slice (3 mm thick) down through and to include an intact stalk/base. Embed face down in the block and the lateral trimmings in a separate block. Cut both through multiple levels. If there is a long stalk an initial transverse section of its resection margin may be taken.

• local mucosal resection: endoscopic or transabdominal is used for stalked polyps (see above) or sessile lesions. Ideally, the latter should be submitted by the surgeon to the laboratory already carefully pinned out onto a cork board or piece of card. Remove and paint the deep and lateral mucosal resection margins. Obtain multiple vertical transverse serial slices (3 mm thick) to include the lesion and underlying base. Where the lesion edge is to within 3 mm of the mucosal margin, sample at right angles to it from a 10 mm slice. Embed the slices face down in the block and cut through multiple levels.

Wedge biopsy:

• usually derived from the edge of a perforated ulcer detected at surgical laparotomy for an acute abdomen. Its base is oversewn and a biopsy taken if the edges show any unusual features, e.g., rolled margins.

• with the mucosal surface upwards bisect or cut into multiple vertical serial slices. Embed the slices face down and cut through multiple levels.

Needle core biopsy:

• up to 1.5 cm long and 1-2 mm diameter, core size is influenced by the patient's anatomy, the nature of the lesion being biopsied, the needle that is used and operator expertise. Some scirrhous carcinomas can be difficult to sample whereas other disease processes lead to fragmentation of the core, e.g., cirrhosis of the liver. Skinny needle cores can be particularly fine requiring careful handling and even painting or immersion in dye (e.g., alcian blue) prior to embedding so that the tissue can be seen when the block is faced at cutting.

• count and measure the maximum core length (mm).

• place intact in cassette between foam insert pads or loosely wrap in moist filter paper.

• cut through multiple levels.

Polyp<1cm diameter-bisect vertically and embed cut surfaces face down

Polyp<1cm diameter-bisect vertically and embed cut surfaces face down

Polyp>1cm diameter-trim off the edges of the head leaving a vertical mid-slice including the stalk and base

Sessile lesion/mucosal resection-paint the deep and lateral resection margins and obtain multiple vertical transverse serial slices to include the underlying base. Where the lesion edge is to within 3mm of the mucosal margin (a) sample at right angles to it from a 10 mm slice

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<10mm>

Figure 2. Gastrointestinal mucosal polyps and local mucosal resections.

Fresh tissue:

• the vast majority of specimens are submitted in formalin fixative but some cases require fresh tissue for frozen sections, e.g., acetylcholinesterase staining in Hirschsprung's disease, or an inflammatory versus malignant lesion at diagnostic laparotomy.

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