Gastrointestinal Specimens

Relevant clinical history

In addition to age and gender, relevant clinical history is often necessary or helpful for interpretation ( Table 16.1 ).

Processing the specimen

• 1.

  Measure and record the dimensions of the mucosal surface and the thickness of the specimen.

• 2.

  Examine the mucosal surface for lesions and describe them including:

  Size (including depth of invasion after sectioning)

  Color:Squamous = white and glistening

  Barrett’s esophagus = pink to red, often mottled in appearance and intermingled with squamous areas

  Shape (polypoid, diffuse, exophytic)

  Consistency (hard, firm, soft)

  Ulceration

  Distance from margins

  Adjacent mucosa (normal white smooth and glistening squamous mucosa or pink granular glandular metaplastic mucosa)

  A photograph and accompanying block diagram is helpful for the evaluation of margins and is highly recommended for these specimens.

• 3.

  Examine the deep margin and note if tumor or muscularis propria is present.

• 4.

  Ink the lateral and deep edges of the specimen with different colors. If the specimen has been oriented, additional colored inks can be used to identify different mucosal margins and the deep margin.

• 5.

  The specimen should be received gently stretched flat and pinned to a paraffin block in formalin. The specimens should be fixed in formalin for at least 3 hours or overnight to ensure the specimen will lay flat once sectioned and processed. Over stretching can cause tissue artifacts. However, unless the specimen is pinned flat, the specimen can contract and the edges curl, making evaluation of the margins difficult. Pins should not be placed in lesional tissue if this can be avoided.

• 6.

  After fixation, the first incision is made in the plane that will demonstrate the closest approach of the lesion to the mucosal margin. Serially section the specimen at 0.2 cm intervals through the entire specimen. The two edge (“tip”) slices are then sliced perpendicular to the margin. Identify the cassette(s) with the closest approach of the lesion to the margin.

• 7.

  The entire specimen is submitted for histologic evaluation with oriented margins. Due to the importance of proper embedding, no more than two fragments should be placed in one cassette.

Sample dictation

Received fresh, labeled with the patient’s name and medical record number and “Esophageal mass ESD,” is an unoriented tan/pink mucosal excision (8.2 × 5.0, excised to a depth of 0.1 cm) pinned out on a paraffin block. A gross photograph is taken. The mucosal surface shows a gray/pink nodular mass measuring 6.6 × 3.5 cm and focally is 0.1 cm from the radial margin. The surrounding mucosa is white and glistening. The radial margin is inked blue and the deep margin is inked black. A gross photograph is taken. The specimen is serially sectioned and entirely submitted in sequential order for microscopic evaluation.

• Micros A1–A2: Perpendicular sections of one edge with margin, two frags per cassette.

• Micro A3–A5: Adjacent slices with normal appearing mucosa and margin, two frags per cassette.

• Micro A6–A12: Slices with lesion with the closest approach to the margin in A7 and A8, two frags per cassette.

• Micro A13–A14: Perpendicular sections of the opposing edge with margin, two frags per cassette.

Processing the specimen

• 1.

  Measure the length and diameter of the esophagus, the dimensions of the stomach, and the attached fat and adventitia.

• 2.

  Stapled margins are removed by cutting away the staple line (as close as possible to the staples) with a pair of scissors. Differentially ink the proximal and distal margin. The proximal margin must be inked quickly as the esophageal mucosa retracts rapidly.

  Ink the radial adventitial margin and radial epigastric margin, if present.

  Locate the lesion by gently palpating the gastrointestinal junction (GEJ) with one finger in the lumen. Open the specimen longitudinally. Avoid cutting across any palpable lesions.

• 3.

  Untreated and/or grossly evident tumors: Describe the lesion including size, color, tumor configuration (exophytic or polypoid, ulcerated, or infiltrative), depth of invasion, location (including relationship of midpoint to SCJ and GEJ), percent of circumference involved, and distance to margins.

  The distance of the midpoint of the carcinoma to the GEJ is recorded and the proportion of the tumor located in the esophagus and in the stomach reported. This helps determine whether the cancer is classified as esophageal or gastric cancer.

  Esophageal cancer:

  Lesion is entirely located within the tubular esophagus and does not involve the EGJ

  Lesion midpoint lies in the distal esophagus and the lesion involves the EGJ

  Lesion midpoint is located at the EGJ

  Lesion midpoint is 2 cm or less into the proximal stomach or cardia and lesion involves the EGJ

  Gastric cancer:

  Lesion involves the EGJ, but the midpoint is more than 2 cm into the proximal stomach

  Lesion midpoint is less than 2 cm into the proximal stomach, but does not involve the EGJ

  Specimens after treatment without a grossly evident tumor: The site of the prior tumor often has the appearance of scarring or shallow ulceration. The tumor bed is best identified by palpation of a firmer area. Describe the tumor bed including size, color, extent of involvement of the wall, location (including relationship to SCJ and GEJ), percent of circumference involved, and distant to margins.

  The distance from the margins (distal, proximal, and deep) should be measured as soon as possible on the fresh specimen as considerable retraction occurs after excision.

• 4.

  Describe uninvolved mucosa:

  Normal esophagus (squamous): glistening smooth white mucosa.

  Normal stomach (glandular): velvety pink/red mucosa with rugal folds.

  Barrett’s mucosa (glandular): pale pink, finely granular, and may be patchy.

• 5.

  Pin out on a board. The specimen is fixed in formalin overnight.

• 6.

  Sections of the tumor, margins, and any additional lesions are submitted the following day.

  After taking the sections of the tumor and margins, the adventitial soft tissue away from the tumor can be stripped from the main specimen to aid in identifying lymph nodes. The fat should be carefully palpated and thinly sectioned. Nodes are virtually always present and may be located very close to the esophagus or stomach. Even small areas of attached adipose tissue need to be searched for lymph nodes. Entirely submit the adventitial soft tissue, regardless of how many lymph nodes are identified. Inspect the perigastric adipose tissue for lymph nodes and submit any nodes found.

Special studies

HER2 testing: Some distal esophageal adenocarcinomas overexpress HER2 and these patients may benefit from targeted therapy. Overexpression can be determined by immunohistochemistry (protein expression) or by in situ hybridization (gene number). The studies are performed on paraffin blocks.

Gross differential diagnosis

The gross appearance and location of lesions of the esophagus are important for diagnosis and classification ( Fig. 16.1 ).

Adenocarcinomas of the esophagus are usually present at or just above the GEJ and have a gross appearance similar to colonic adenocarcinomas. The main tumor is often tan/pink, polypoid, and may have an ulcerated center. These tumors often tunnel underneath the proximal uninvolved squamous mucosa and may be present at the proximal or distal margins in the submucosa. This is of great importance when evaluating margins intraoperatively. A section that includes the full thickness of the esophageal or gastric wall must be taken in order to detect submucosal carcinoma.

Barrett’s mucosa is an abnormal type of glandular mucosa occurring in the esophagus. It is pale pink, finely granular, and may be patchy and interspersed in areas of remaining squamous mucosa, which is white, smooth, and glistening. Barrett’s mucosa is found extending proximally from the GEJ. The GEJ is defined by the proximal limit of the gastric rugal folds. Barrett’s mucosa is often seen in association with esophageal adenocarcinomas, although the tumor may have obliterated the precursor lesion.

Squamous cell carcinomas can occur at any level of the esophagus. These tumors may be exophytic (intraluminal), ulcerating, or present as a diffuse thickening with narrowing of the lumen. In the majority of cases, preoperative radiation therapy will have been given. The residual tumor may be difficult to appreciate grossly and may consist of areas of shallow ulceration or irregular/granular appearing squamous mucosa. Squamous cell carcinoma in situ is typically present in the adjacent esophagus.

Tumors after treatment: If there has been a marked response, the main tumor mass may be absent with only a shallow ulceration present at the tumor bed. Postradiation changes may be present including fibrosis and esophageal mucosal erosions. It is impossible to distinguish residual viable tumor from scarring secondary to treatment on gross examination. If grossly visible tumor is not identified, it may be prudent to completely sample the indurated area on palpation corresponding to the tumor bed.

Leiomyomas of the esophagus almost always arise from the muscularis propria and only rarely from the muscularis mucosae. The tumors are well circumscribed, pink to white, and have a whorled appearance, similar to uterine leiomyomas. Most are present within the wall, but some may project into the lumen as a polypoid mass. Gastrointestinal stromal tumors (GISTs) have a similar appearance, but are less common than leiomyomas in the esophagus.

Zenker’s diverticulum (“pharyngeal pouch”) is an acquired outpouching of the esophageal wall. It is a pseudodiverticulum like those in the sigmoid colon, as it lacks a complete muscular wall. Current treatment is with endoscopic diverticulotomy with stapling.

Microscopic sections

Sample dictation

Received fresh labeled with the patient’s name and unit number and “esophagus” is an esophagogastrectomy specimen including esophagus (15 cm in length × 4 cm in circumference), stapled resection margin (2.9 cm, inked blue), and stomach (5 cm in length × 12 cm in circumference × 3.2 cm depth), stapled distal resection margin (16 cm in length, inked black), radial adventitial soft tissue (up to 0.7 cm, radial adventitial margin inked orange), and attached epigastric fat (up to 2.5 cm, radial epigastric margin inked orange). The proximal margin is entirely submitted en face for frozen section as FS1, and the closest perpendicular distal margin is representatively submitted as FS1.

There is a tan–white scar (3.6 cm longitudinal, 2.3 cm transverse) in the distal esophagus (midpoint: 1.1 cm proximal to GEJ) that is 9.4 cm to the proximal margin, 7.3 cm to the distal margin, and 1.9 cm to the radial margin. The lesion is grossly confined to the mucosa with a maximal depth of 0.2 cm. The remaining esophageal mucosa is white and unremarkable. The gastric mucosa contains a tan polyp (0.3 cm in greatest dimension) that is 5.4 cm to the distal margin and 3.4 cm from the scar.

There are 14 lymph node candidates (ranging from 0.1 to 0.4 cm in greatest dimension). Gross photographs are taken.

Representative sections are submitted according to a diagram.

• Micro A1: FS1 remnant, one fragment

• Micro A2: FS2 remnant, one fragment

• Micro A3–A14: Scar, submitted proximal to distal, per diagram (A6–A7 = deepest extent and closest to radial margin, A11–A14 with relationship to GEJ), one fragment each, entirely submitted

• Micro A15: Gastric polyp, one fragment, entirely submitted

• Micro A16: Six candidate lymph nodes, whole, six fragments

• Micro A17–A18: Two candidate lymph nodes each, differentially inked and bisected, four fragments each

• Micro A19: One candidate lymph node, sectioned, five fragments

• Micro A20–A23: Remainder of adventitial soft tissue, multiple fragments, entirely submitted

• Micro A24: Three candidate lymph nodes, differentially inked and bisected, four fragments

• Micro A25: One candidate lymph node, whole, one fragment

Pathologic prognostic/diagnostic features sign-out checklist for esophageal carcinomas

This checklist incorporates information from the CAP Cancer Committee protocols for reporting on cancer specimens (see www.cap.org/ ) as well as other resources. The specific details of reporting the elements may vary among institutions.

Relevant clinical history

In addition to gender and age, clinically relevant information is often necessary or helpful for the interpretation of specimens ( Table 16.3 ).

Processing the specimen

• 1.

  Measure and record the dimensions of the mucosal surface and the thickness of the specimen.

• 2.

  Examine the mucosal surface for lesions and describe them including:

  Size (including depth of invasion after sectioning)

  Color

  Shape (polypoid, diffuse, exophytic)

  Consistency (hard, firm, soft)

  Ulceration

  Distance from margins

  A photograph and accompanying block diagram is helpful to document the specimen and to evaluate the margins.

• 3.

  Examine the deep margin and note if tumor or muscularis propria is present.

• 4.

  Ink the lateral and deep edges of the specimen in different colors. If the specimen has been oriented, additional colors of inks can be used to identify different mucosal margins and the deep margin.

• 5.

  The specimen is generally received gently stretched flat and pinned to a paraffin block in formalin. The specimen should be fixed in formalin for at least 3 hours or overnight to ensure the specimen will lay flat once sectioned and processed. Too much stretching of the specimen can cause tissue artifacts. However, unless the specimen is pinned flat, the specimen can contract and the edges curl, making evaluation of the margins difficult. Pins should not be placed in lesional tissue if this can be avoided.

• 6.

  Identify the area with the closest approach of the lesion to the radial margin. Serially section the specimen at 0.2 cm intervals through the entire specimen. The area of closest approach should be included in the slices through the full specimen and not in the end or “tip” slices. These end (“tip”) slices are then sectioned perpendicularly to the margin. The cassettes with the closest approach to the margin should be identified.

• 7.

  The entire specimen is submitted for histologic evaluation in sequential order. Due to the importance of proper embedding, no more than two fragments should be placed in one cassette.

Processing the specimen

• 1.

  The specimen is a blunt ended portion of stomach closed with a staple line. Measure the stomach and staple line. Cut away the staple line, staying as close as possible to the staples. Ink the margin.

• 2.

  Carefully examine the mucosal surface for any abnormalities. The most common mucosal lesion is a benign polyp, which will form a small raised polypoid mass.

  Carefully examine the serosal surface for any abnormalities.

  Gently palpate the specimen to determine if any nodules are present. The most common lesion of the gastric wall is GIST, which forms a well-circumscribed white firm mass in the muscularis. Rarer leiomyomas and schwannomas have the same appearance.

• 3.

  Completely sample all abnormal areas. Include a section of the closest approach to the margin. If no abnormalities are found, two blocks of representative tissue are submitted.

Sample gross description

Received fresh labeled with the patient’s name and unit number and “gastric sleeve” is a 20 × 18 × 3.4 cm portion of stomach with a 19 cm staple line (inked blue). The serosa is tan/pink and smooth. The mucosa is tan/pink and normal in appearance. No masses or other lesions are identified. Representative sections are submitted for microscopic evaluation.

• Micro A1–A2: Stomach, two fragments per cassette.

Processing the specimen

• 1.

  Record the dimensions of the stomach, staple lines, epigastric fat, and omentum (if present).

  Examine the outer surface of the intact specimen for evidence of tumor invasion through the wall and describe the serosa (color, glistening, dull, indurated, retracted, nodules). Tumor implants on the peritoneal surface (not due to direct extension by tumor) are considered distant metastases. Areas of concern can be inked to help identify them for later gross inspection or tissue sampling.

  Remove the proximal and distal staple lines and ink the margins.

  After the specimen is opened in the step below, the mucosal edges tend to curl under, and it is sometimes difficult to identify the resection margins. The ink can help with this identification. Cassettes can also be clipped to the edges of the margins to help to identify them.

• 2.

  Very gently palpate the mucosa and wall to locate the lesion before opening the specimen. The mucosa is very delicate and should be touched as little as possible. Open the stomach along the greater curvature, unless a lesion is present at that site. Avoid cutting through any lesions. Inspect the proximal and distal margins for the presence of esophageal or duodenal mucosa, which may be minimal.

• 3.

  Identify mucosal lesions and describe:

  Size (including depth of invasion)—Ink the deep margin of any lesions and make several cuts to evaluate the depth of penetration into the wall.

  Color

  Shape (ulcerating, polypoid, diffuse, exophytic)

  Consistency (hard, firm, soft)

  Margins of ulcers (irregular, rolled, puckered)

  Location (cardia, fundus, antrum, greater or lesser curvature of corpus, anterior or posterior wall, pylorus). Cancers with the epicenter ≤2 cm from the esophageal gastric junction (EGJ) but not involving the EGJ are defined as gastric cancers. If the EGJ is involved, the carcinoma is defined as an esophageal cancer.

  Perforation of wall

  Relationship to resection margins—The distance to margins should be measured on the fresh specimen as soon as possible after resection, as considerable contraction of the specimen can occur.

  Mucosal margins are proximal and distal.

  The radial margins consist of nonperitonealized soft tissue and consist of the lesser omental (hepatoduodenal and hepatogastric ligaments) and greater omental margins.

  Relationship to the visceral peritoneum—Tumor penetration of the visceral peritoneum (grossly corresponding to tumor present at the surface of the perigastric adipose tissue) is classified as T3, whereas tumor that invades into perigastric soft tissue (e.g., greater omentum) but not through visceral peritoneum is classified as T2.

  If the nature of the lesion (i.e., carcinoma vs. lymphoma) has not been established (e.g., by previous biopsy) and is not evident from the gross examination, a frozen section or cytologic preparation (e.g., a touch preparation) may be useful to aid in apportioning tissue (e.g., saving tissue for hematologic studies if lymphoma is suspected).

  Describe the uninvolved mucosa including color, texture (glistening, hemorrhagic, granular, flattened, fibrotic, constricted), and the preservation or absence of rugal folds.

• 4.

  Pin out the stomach on a paraffin block and fix overnight in formalin. The following day, submit microscopic sections of stomach and lesions.

• 5.

  The greater and lesser omental tissue (except for that directly deep to the tumor) is removed to find lymphnodes. Section and carefully examine any attached fat subjacent to the mass for lymph nodes. Lymph nodes in the greater omentum are found closest to the stomach and decrease in number more distantly from the serosa.

Palpate and thinly section through this soft tissue and submit all lymph nodes. Describe including size of largest node and any evidence of metastasis (white, hard). Tumor deposits in subserosal fat without evidence of lymph node tissue are considered lymph node metastases. Therefore, it is very important to distinguish separate tumor nodules from direct extension of the cancer into adjacent adipose tissue. It is recommended that at least 16 regional lymph nodes be assessed.

Gross differential diagnosis

The gross appearance of stomach lesions often provides important clues to their origin ( Fig. 16.2 ).

Benign ulcers tend to be sharply delineated with converging mucosal folds. The edges are usually flat or only slightly heaped up. About 10% of ulcers thought to be clinically benign are shown to be due to malignancy after pathologic examination. Malignancy is more commonly associated with ulcers over 2 cm in size.

Gastric carcinomas of intestinal type are similar in appearance to colonic adenocarcinomas and usually arise in the antrum. The edges are usually heaped up and serpiginous with a central ulcer bed. Polypoid and villous architecture may be present. Nodularity around the edge of an ulcer or an exophytic component is more common in carcinomas. However, some tumors may be ulcerating and lack a heaped up border. Mucosal folds radiating from the ulcerated area are usually absent. Intestinal type carcinomas are associated with chronic atrophic gastritis that causes marked thinning and flattening of the surrounding mucosa. This type of carcinoma is more common in males than females.

Diffuse type (signet-ring cell carcinomas) are usually located in the prepyloric region or body of the stomach and can have minimal or absent superficial mucosal involvement. The only sign of an early lesion may be subtle mucosal effacement or erosion, which may be better appreciated in a fixed pinned out specimen. In advanced lesions, the wall of the stomach is markedly thickened due to the infiltrative nature of the malignant cells (termed “linitis plastica”) but the muscularis propria can still be identified grossly and appears thickened and hypertrophic. It may be difficult to determine the extent of the tumor grossly. Margins can be difficult to evaluate by frozen section as the tumor cells may be present at any level in the gastric wall and can mimic histiocytes or other benign cells. There is a similar incidence in males and females.

Lymphomas can have a gross appearance very similar to signet-ring cell carcinomas with little or no mucosal involvement, including ulceration. Although both malignancies commonly present in the distal stomach, they rarely involve the pyloric region. The gross appearance may resemble hypertrophied mucosal folds or may appear to be a large mass, sometimes with perforation. The wall may appear diffusely thickened (termed “linitis plastica”).

GISTs arise from the specialized interstitial cells of Cajal in the muscularis propria. Some protrude into the lumen with ulceration of the overlying mucosa. Others protrude on the serosal side. The cut surface is tan and lacks the whorled appearance of smooth muscle tumors. Most (60–70%) arise in the stomach with fewer in small intestine (30–40%), colon or rectum (5%), or esophagus (5%). The risk of malignant behavior is related to location (gastric tumors are less likely to behave in a malignant fashion), size, and mitotic rate. Leiomyomas are uncommon in the stomach (<10%).

Patients with Stratakis–Carney dyad develop gastric GIST and paragangliomas. Mutations are in the succinate dehydrogenase genes ( SDHx mutations). These patients tend to be younger and female. Loss of SDHB by immunohistochemistry is predictive of germline mutations in any of the genes, as malfunction of one protein results in degradation of the entire complex. GIST with SDHx loss often does not have a mutation in KIT or PDGFRA (termed “wild-type GIST”). These tumors also tend to be epithelioid or mixed in type and have an indolent clinical course.

Microscopic sections

Sample gross description

Received fresh labeled with the patient’s name and unit number and “partial stomach” is a partial gastrectomy specimen including stomach (12 × 11 × 3.5 cm), duodenum (1.1. cm in length × 2.1 cm in circumference) with attached epigastric fat (up to 2.1 cm thick; the radial margin is inked orange), and omentum (10 × 3 × 0.9 cm). The stapled proximal margin is 5.7 cm in length and inked blue. The stapled distal margin is 2.2 cm in length and is inked black.

The serosa is tan and contains an area of puckering (1.1 cm; inked green) along the posterior aspect. There is a centrally ulcerated tan mass (3.1 × 2.7 × 1.2 cm) in the antrum and subjacent to the puckered serosa that is 6.7 cm to the proximal margin, 3.9 cm to the distal margin, and 2.9 cm to the radial epigastric margin. The mass invades the wall to the maximal depth of 1.4 cm. The remaining mucosa is tan and unremarkable.

Twelve candidate lymph nodes (measuring 0.1–0.6 cm) are identified in the epigastric adipose tissue. Seven candidate lymph nodes (measuring 0.4–0.6 cm) are identified in the omentum.

The proximal margin is perpendicularly submitted for frozen section as FSA1. The distal margin is entirely submitted en face for frozen section as FSA2. Photographs are taken. Representative sections are submitted for microscopic evaluation.

• Micro A1: FSA1 remnant, one fragment.

• Micro A2: FSA2 remnant, one fragment.

• Micro A3–A7: Mass (A4–A6 with deepest extent and entirety of puckered serosa), one fragment each, representatively sampled.

• Micro A8: Closest radial epigastric margin en face, one fragment.

• Micro A9: Pyloric sphincter, one fragment.

• Micro A10: Six candidate lymph nodes, whole, six fragments.

• Micro A11: Four candidate lymph nodes, whole, four fragments.

• Micro A12: Two candidate lymph nodes, inked blue and black and bisected, four fragments.

• Micro A13: One candidate lymph node, sectioned, six fragments.

• Micro A14: Six candidate lymph nodes, whole, six fragments.

Pathologic prognostic/diagnostic features sign-out checklist for stomach carcinomas

This checklist incorporates information from the CAP Cancer Committee protocols for reporting on cancer specimens (see www.cap.org/ ) as well as other resources.

Relevant clinical history

In addition to age and gender, clinically relevant information is often necessary or helpful for interpretation ( Table 16.5 ).

Processing the specimen

• 1.

  Specimens submitted in formalin can be processed like other small biopsies (see section on “Biopsy”).

• 2.

  Some specimens may be submitted in Hollendes, possibly a better fixative for histologic detail. The biopsies are on mesh to preserve orientation. The biopsies must fix in Hollendes for 2–4 hours.

• 3.

  Each biopsy with attached mesh is wrapped together in lens paper. Submit each biopsy in a separate cassette in order for each one to be oriented by the histotechnologist. Tissue fixed in Hollendes must be washed in water for at least 3 hours up to overnight. Transfer to formalin and submit after washing.