Gross Description and Processing of Specimens

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Gross Description and Processing of Specimens

Chapter Outline

Introduction

The surgical pathologist reports the histopathologic diagnosis and specific information relating to prognosis and treatment. Therefore, one must have sufficient familiarity with the management of gynecologic and obstetric disorders to assure that the pathology report communicates the clinically relevant information. This chapter provides an approach to the processing of gynecologic and obstetric tissue specimens. The techniques of gross examination and the method of reporting the pathologic findings are guided by the clinical principles on which patient management is based. Several textbooks are now devoted entirely to this topic.13

In general, most tissue specimens submitted to the surgical pathology laboratory fall into one of three categories:

The main purpose of a biopsy is to provide a histologic diagnosis that will guide management. Since biopsy specimens tend to be small and without specific gross features, the major pathology resides in the histology. The gross description is important mainly to ensure that what is received in the pathology laboratory and submitted for microscopic examination matches the slides returned from the histology laboratory for the pathologist to examine. Disparity between the findings on a slide and those expected based on the gross description is often the only clue that a slide or block may have been mislabeled. A good gross description therefore should be precise and brief. Examples of good descriptions are ‘3 ovoid fragments 2 to 4 mm in diameter,’ ‘multiple shreds of tissue 5 cm in aggregate,’ or the exact size given in three dimensions. For some specimens, it is also useful to note whether it is largely blood, mucin, or tissue.

In contrast, the gross description that the pathologist provides in therapeutic resections may be the most important aspect of the entire report. These are usually larger operative specimens and, after the specimen is examined in the gross state and dissected, it is normally discarded after several weeks. There is no way to return to the specimen and determine the position and size of any lesion, its margins, its relation to neighboring organs, or any other facets about its growth pattern after this time.

For operative specimens, particularly those containing a malignancy, information in the surgical pathology report should describe the extent of the tumor and specific features that relate to prognosis and staging. The adequacy of the surgical treatment as well as the need for additional therapy depends on these findings. Since the gynecologic surgeon has seen the pathology in vivo, it is important that the surgeon communicate the operative findings, since these will bear directly on how the pathologist processes the specimen. For example, adequacy of resection margins requires an appreciation of the orientation of the specimen to certain anatomic landmarks that are obvious to the surgeon, but which the pathologist cannot always reconstruct in the laboratory.

A good gross description enables the reader to reconstruct an image that corresponds to the specimen and its lesion. Since the histologic diagnosis for many tumors has been made by biopsy before the operative procedure, the gross description of the specimen should focus on the site and extent of the lesion and its relationship to adjacent structures. Key findings should be suggested from the gross examination of the specimen. Microscopic findings should be complementary to those identified grossly, and it should be uncommon for them to be in conflict. A careful gross examination is mandatory to ensure that the appropriate microscopic sections are obtained. Conversely, an inattentive gross examination often leads to preparation of needless ‘representative’ slides (read: ‘haphazard’ or ‘taken without thinking’), or, worse yet, an incorrect diagnosis. An accurate pathology report and microscopic evaluation is dependent on an accurate evaluation of the specimen in the gross state.

The final diagnosis of a tumor includes its histologic type, grade, dimensions, location, and extent, as well as the adequacy of the resection margins, presence of lymphatic or vascular invasion, and status of the regional lymph nodes. Since 2004, all hospitals wishing to achieve certification/designation as a cancer institute by the American College of Surgeons must issue pathology reports listing all of the data points deemed mandatory by the College of American Pathologists (CAP). An appropriate gross description and selection of blocks for microscopy requires a full understanding of what should be in the final report for each specimen type, and why.

Section Codes and the Report

Many operations result in two or more separate specimens being submitted to the pathology department. Cervical examinations often produce two or three colposcopically directed biopsies plus endocervical curettage. Twenty or more specimens from a staging laparotomy are not uncommon. As a first step, each container received should be numbered and checked to ensure that all specimens removed have in fact reached the pathologist. This information is usually listed on the requisition sheet (‘specimens submitted’). Each specimen should be uniquely labeled (see later). Payment issues also require that each container be given an identifiable diagnosis.

Section Codes

It is important that every department settle on a numbering system that is clear and used consistently throughout the specimen. The most common systems in use today are computer generated, providing the accession number for the overall case, the container sub-number for each portion of the specimen when it is received in multiple parts, an identifier for each paraffin block, the level within each paraffin block, and the type of stain used with any given slide.

Most systems use a one- or two-letter prefix to identify the general type of case received (S = surgical, C = cytology, A = autopsy), followed by a two-digit number designating the year (00 = 2000), followed by a sequential digit number. One system, in common use worldwide, then assigns a unique letter to each container received, starting at the beginning of the alphabet, i.e., ‘A.’ Each block sampled from that specimen/container then receives a sequential number, e.g., A1, A2, . . . An. Each subsequent specimen/container receives the next available letter, e.g., B, with multiple blocks from the container having sequential numbers, B1 . . . Bn. If multiple levels of a single paraffin block are made, a practice for cervical biopsies in many institutions, the letter ‘L’ is appended with the designation of the slide level, e.g., -L2 for the second level of the block. Thus a typical specimen number might be SG-00-02167 B4-L2, which translates to ‘Surgical specimen of a gynecologic nature, received in year 2000, accession number 2167, container B, fourth block taken from specimen B, and second slide prepared from that paraffin block.’ Variants of the above system typically utilize letters in upper and lower case, Roman numerals, and Arabic numbers, usually in some combination and defined sequence. Of course, multiple numbering systems exist, and it is not the purpose of this chapter to pick which is best; the purpose is rather to help ensure clarity in whatever system is used.

Location of Section Codes in the Report

Most pathologists prefer a section code summary at the end of the gross text while some prefer entering block codes within the gross text. In either case, the report must be clear, both to the pathologist and to any person who at a later time will need to utilize the report. Block summaries, if used, may duplicate substantial parts of the gross, but cannot be used in its place. Including the block submission within the body of the gross description may be easier and more efficient for the person cutting in the specimen: ‘The borders in one region are sharp and distinct from the surrounding myometrium (Block B10) while elsewhere it blends into the adjacent myometrium (Block B11).’ However, having a section key at the end of the dictation may make histologic examination easier and more efficient. If the block codes are listed sequentially at the end of the report, the specific site and feature identified require presentation in sufficient detail so that the reader can easily link the gross description with the slide. Using the example above, it would be inappropriate for the coding block at the end to state that B10 and B11 are myometrium as it is unclear which section has the sharp borders and which has blurred borders. A section code at the end might better read, ‘B10 Myometrium, sharply circumscribed medial border, B11 Myometrium, blurred indistinct borders.’

Specimen and Site Identification

Regardless of the section code method used, it is critical that the reader can link the tissues received to the sections processed and both to the final diagnoses. For example, four cervical biopsies from the same patient are received in separate containers, but from the same operation. Information on the requisition slip indicates that the colposcopically directed specimens are from 3, 6, 9, and 12 o’clock, respectively. In this example, the accession number might be SG-00-02167, and the containers labeled A, B, C, and D, respectively. Since the paraffin block usually is identified solely by the code, then this same code should appear throughout. Thus, the gross might read ‘A. 3:00 bx’ (the wording exactly replicating what the clinician wrote on the container itself) while the final diagnosis would include ‘A. Cervix, Biopsy at 3 o’clock: Diagnostic finding.’ Obviously, the label on the slide must provide all of the necessary identifiers.

A most perplexing problem we encounter in referred specimens is where the label assigned to the container in the gross description differs from that given in the microscopic description to that given in the final diagnosis. For example, the container might be ‘A’ in the gross description, which refers to a specimen consisting of uterus, ovaries, and fallopian tubes, whereas the final diagnosis is ‘1. Endometriosis of the ovary.’ Such cases require substantial effort on the part of the consultant pathologist to determine (and sometimes guess) which gross description truly belongs to which slide and both to the listed final diagnosis.

General Aspects of Gross Decription and Cutting in of Specimens

Gross Description

If possible, describe specimens received in the fresh state before fixation. Formalin alters natural color and consistency of tissue. The opening sentence of the gross description should indicate how the tissue is received (fresh or fixed) and labeled. Does the specimen received correspond with its label? For example, the container received states ‘Uterus, tubes, and ovaries,’ yet the left adnexa is absent. Such a gross description might read, ‘Received fresh is a uterus and right ovary and fallopian tube. The left ovary and fallopian tube are absent.’ Give measurements and weights of the individual diseased organs (e.g., ‘the 710 g, 18 × 15 × 8 cm uterus’). Conglomerate measurements and weights are meaningless (uterus, tubes, and ovaries which together weigh 710 g and measure 18 × 15 × 8 cm) since they are ambiguous as to the role played by each organ and where the pathology resides.

The gross description should proceed in an orderly fashion, focusing on the primary lesion. Several common methods are in use. In one, the pathology in any given container/specimen is emphasized first. This highlights the pathology and de-emphasizes the normal. In practice, descriptions are full but economical in words and space. The second method is to follow a routine pattern whereby the same order is followed in every case, e.g., ovary, fallopian tube, uterine corpus, cervix, etc. This method, while usually easier for the novice, lends itself to loquacious reports filled with tedious description. All too often the true pathology is treated least well or even inadequately, as it is buried deep in the description. Not uncommonly, such travelogues lead to reports several pages long, but with a description of the tumor under several lines in toto. With the novice, detailed descriptions force careful examination, but, with experience, can be refined to a more concise and readable form.

Avoid elaborate descriptions of normal incidental anatomy. In a radical hysterectomy for cervical cancer, there is no need for an overly elaborate description of a normal fallopian tube. The following is excessive, ‘7 cm long, elongate structure with a 1 mm internal diameter and 4 mm external diameter with a tan, smooth, glistening serosa, a 2 mm thick wall, and a lumen without identifiable abnormality.’ Simply ‘the fallopian tube is 7 cm long, 4 mm in diameter and unremarkable’ will do.

Similarly, we believe experience should allow the pathologist to describe grossly obvious lesions in diagnostic terms rather than nonspecific and frequently long-winded descriptions, a practice with which many also disagree. Leiomyoma, or, where useful, the diagnostic term with one or two adjectives (‘well-circumscribed, whorled leiomyoma lacking hemorrhage or necrosis’), is far more useful than the excessive description (‘numerous, discrete, circumscribed, rounded lesions with a bulging whorled cut surface, white in color, and compressing the adjacent myometrium’), which is tedious to read. At worst the description is vague (‘rounded lesions’). Purposeful uncertainty, where it exists, can also be introduced with adjectives (‘5 cm soft, focally necrotic leiomyomatous nodule with irregular borders suspicious for sarcomatous change’).

The gross description, especially of small specimens, should conclude by stating how much of the tissue has been processed for microscopic examination. This is especially important in the case of endometrial curettings removed for a suspected intrauterine pregnancy where neither chorionic villi nor other tissues of fetal origin are found and all of the tissue has been submitted. Specify the number of each type of block sampled and from where each was obtained. An example of a useful gross description is ‘The endometrium, which is 2 mm thick, discloses no obvious tumor. The entire endometrium including the superficial myometrium is blocked and submitted in toto.’

Inking

Application of ink, often in multiple colors, can be useful to identify various surgical margins, which on histologic sections is helpful to determine if the lesion is truly present at the margin or is present only where the tissue has been cut on a bias, thus simulating a margin (ink absent). If used, apply ink sparingly and blot dry to prevent spillover or running. Acetone or distilled white vinegar can be used to set the ink. As inking is a procedure all too often done indiscriminately, determine first whether it is even useful. There is no need to ink a uterine serosa in cases of cervical squamous intraepithelial lesions (SIL) or in cases where the endometrial cancer is small and noninvasive and the serosa is obviously normal and uninvolved. Ink sometimes is helpful (and sometimes the only clue) in identifying the surface of the ovary when replaced by tumor. Ensure also that the ink does not inadvertently conceal disease, e.g., endometriosis or a metastasis on the serosa.

Fixatives

Formalin-based fixatives are generally the most practical and commonly used today. Tissue submitted in blocks for processing should be less than 3 mm thick. Thicker fragments are difficult to dehydrate and inhibit paraffin infiltration, thus leading to suboptimal slides. Sometimes, it is much easier to cut sections from tissue that has been fixed for several hours instead of attempting to cut 3 mm thick slices directly from a fresh specimen. Large specimens should be cross sectioned and cut at intervals 1 cm thick or less. This permits adequate penetration by formalin, after which the tissue can be trimmed into 3 mm thick sections. For large specimens, e.g., uteri removed for leiomyomata, placing the tissue blocks into cassettes (with all labeling complete) and retaining them in the fluid fixative for an extra day facilitates better sections. If fresh or frozen tissue is required for special studies, this should be collected prior to fixation.

Number of Sections Required

Judging what must be sampled to optimally examine a specimen is one of the more controversial subjects not only in gynecologic pathology, but in all branches of surgical pathology. In general, the authors believe that far too many blocks are usually taken, adding expense without furthering diagnostic information gained. A useful exercise is to determine what single slide would be taken if the entire prosection permitted were limited to the single slide. This forces thinking about which single slide would demonstrate the lesion as well as pertinent margins or neighboring relations. Such forethought often has a major influence on how a specimen is opened and/or sampled. For example, an excisional biopsy of vulvar tumor might be best sampled by six equidistant perpendicular blocks sampling the central tumor, deep margin, and lateral margins rather than eight parallel lateral margins, shave margins of the base, and only several of the tumor. Leiomyomas/equivocal leiomyosarcomas should include not only the tumor but also the border with neighboring tissue and margins if possible. Endometrial tumors can easily be sampled to include the adjacent ‘normal’ endometrium.

Vulva

Wide Local Excision

In general, wide local excisions are performed for noninvasive neoplasms such as vulvar intraepithelial neoplasm (VIN) 3 or Paget disease of the vulva, as well as superficially invasive (less than 1 mm) stage 1 carcinomas. Lymph node dissections are added for stage 1B carcinomas (greater than 1 mm invasive). Orientation is critical in these specimens and, if not clearly indicated, consultation with the surgeon may be required. Operative specimens often include labia minora and majora, clitoris, perineal body, and perianal tissue (Figure 35.1). Describe and measure the lesions, distances to resection margins, and the anatomic structures involved. Examine the coloration and surface texture carefully as intraepithelial lesions are subtle, typically red-brown to white and roughened.

As intraepithelial lesions are often multifocal and difficult to discern macroscopically, all surgical peripheral and deep resection margins should be evaluated microscopically. Sections parallel to margins (‘tangential’) may be taken to evaluate the excision lines; however, one difficulty commonly encountered in parallel sections for evaluation of margins is to determine if tumor found in the slide truly involves the margin or was from the inner face, and therefore not a true representation of the margin.

For discrete tumors, such as squamous cell carcinoma, multiple full thickness sections perpendicular to the skin surface and radiating outward from the lesion are advantageous as the central lesion, margins, and intervening areas can be included in one slide and tumor close to the margin is easy to evaluate (Figure 35.2). Facilitate sectioning by pinning the specimen on a corkboard or a block of paraffin and fix for several hours or overnight. Diagrams or photographs are often useful.

Radical Vulvectomy

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