Gross Examination of Breast Specimens

Goals and Requirements of Gross Examination

The gross examination of any breast tissue sample involves documentation of what was received by the pathology laboratory, how the tissue was handled in the pathology laboratory, the gross findings identified (and how they correlate with the expected findings), and what was submitted for histological examination.

Whether the breast sample being examined is a core biopsy or a surgical sample performed for cancer or for other reasons, the pathologist should be aware of the expected clinical or imaging findings. Adequate correlation with the relevant medical information frequently requires access to relevant clinical notes and imaging reports. If your practice does not have access to relevant medical records, other methods of communicating these details will be essential to establish with your clinicians. Requiring this information on pathology requisition forms for breast tissue samples or other methods of direct or indirect communication with clinicians is necessary. An example of a standardized list of imaging/clinical information to obtain before grossing a breast surgical specimen is shown in Table 6.1 .

Breast tissue removed for any reason may contain either an expected or unexpected carcinoma that may require ancillary studies (estrogen receptor/progesterone receptor [ER/PgR] and/or human epidermal growth factor receptor 2 [HER2]), and the tissue handling requirements recommended by the College of American Pathologists (CAP) and the American Society of Clinical Oncology (ASCO) have set standards for handling of breast specimens for such events. These include preanalytical variables such as fixation and time to fixation (ischemic time). Documentation of elements such as ischemic time, time in fixation, and type of fixation are required by CAP in these cases and typically are documented at the time of gross description. Table 6.2 contains a summary of breast tissue handling recommendations to ensure accurate ER/PR and HER2 testing of breast cancers.

For cancer cases, gross examination provides essential information for tumor-node-metastasis (TNM) staging. CAP has published fairly comprehensive protocols for examination of breast specimens with either invasive carcinoma or ductal carcinoma in situ (DCIS). CAP-required or recommended reporting elements rely on a thorough initial gross examination and are essential for establishing an accurate pathological T stage and accurate margin status. These include accurate determination of size, focality, extension into skin or chest wall/skeletal muscle, and inflammatory changes. Gross sampling techniques to determine the number of involved lymph nodes (pN stage), margin status, and appropriate sampling of cancer to determine other histopathological features are also a goal of the initial gross examination of a cancer case.

Specimen Types

Knowing and documenting exactly what type of breast specimen the pathology laboratory has received is the essential first step (after confirming patient identifiers) to handling a breast specimen appropriately. In most cases, this information should be clearly documented on the specimen requisition form, and if not, additional inquiry should be made. The individual performing the gross examination needs to be aware of the spectrum of specimens that can be encountered and the differences between them to recognize errors in designation or unusual findings that may require clarification with the radiologist or surgeon before proceeding. A list of common types of breast specimens and their clinical indications is provided in Table 6.3 . See the following specific sections for more detailed discussion of the gross examination of each specimen type.

Key Questions to Ask Before Grossing/Use of Templates and Standard Operating Procedures

There are a series of key questions that should be asked regarding a surgical breast specimen before tissue sampling occurs (see Table 6.1 ). Probably the most important initial question is: What are the expected imaging/clinical findings? The grossing pathologist, trainee, or pathology assistant needs to know specifics here, including what the total number of expected lesions are, what their expected locations are within the breast (in mastectomy specimens) in relation to each other, and whether all lesions are expected to contain a clip or biopsy site changes. Clinically expected but grossly unapparent lesions will frequently be missed on initial tissue submission without this information. Knowing the specific imaging findings (calcifications, mass, magnetic resonance imaging [MRI] enhancement), prior biopsy diagnoses or surgeries, and size of each lesion will also confirm gross expectations (because some lesions may not be grossly apparent) and the extent of the tissue sampling required.

Another essential question to ask is whether the patient was treated before surgery with neoadjuvant therapies. Invasive cancers treated with neoadjuvant chemotherapy can become undetectable by imaging and have only subtle findings on gross examination that indicate the location of the prior tumor bed. Many institutions also have different tissue sampling protocols for neoadjuvant treated cases, so it is critical to know whether this is the type of specimen you are dealing with up front (see later for additional discussion of neoadjuvant treated cases).

Cases in which the lesions are not grossly apparent may be aided by specimen radiography to identify the expected calcifications, clips, or densities. However, some lesions may also not be apparent on radiography (e.g., MRI enhancement and postneoadjuvant residual cancer). Therefore, careful correlation with the expected location of lesions seen on imaging with where they would be expected to be found in the gross specimen must guide sampling. Careful palpation and visual examination of the sliced specimen should also be performed to identify both expected and unexpected findings.

It can be helpful to use a gross template to ensure that the tissue sampling occurs with these clinical correlation questions in mind. Fig. 6.1 shows an example of a grossing template that helps ensure that the person grossing uses available clinical and radiological information at the time of grossing to guide the gross description and tissue sampling. These templates can be modified to the needs of each practice and help standardize grossing techniques.

Standard Tissue Sampling for Grossly Apparent Lesions

When dealing with a grossly apparent mass or lesion, the gross examination is usually straightforward. After documentation of the gross size of the mass in three dimensions, the tissue samples need to be submitted so that this size can be confirmed microscopically. This can be accomplished by submitting samples so that complete cross sections of the largest dimensions are submitted (in larger lesions this will be multiple sections from composite sections). In addition, submission of samples immediately flanking the grossly obvious lesion is recommended to ensure the histological findings do not continue beyond the grossly obvious lesion. Additional microscopic measurements to obtain accurate size measurements may be needed in these circumstances. Relevant precursor lesions may also be discovered in the immediately adjacent tissue. Samples of margins close to the grossly apparent lesion should also be submitted. If more than one lesion is present and they are close together (within 1–2 cm), tissue samples between the lesions should also be submitted to determine whether the lesions are connected and should be considered a single lesion ( Figs. 6.2 and 6.3 ).

In breast pathology, the extent of the histological lesions is frequently different from what was apparent on gross examination. For example, a mass that was expected to be invasive may be mostly DCIS with smaller areas of invasion. Therefore, the tissue must be submitted with a detailed description or map of what was submitted such that the true size of each histological finding can be appropriately established by anyone reading the gross description. It is insufficient to state “representative sections were submitted in cassettes A1 through A10,” because this statement does not make clear how these sections relate to one another. In this example, if invasive carcinoma was only identified in slides A3 and A8, the pathologist would not be able to tell whether these were two separate invasive foci or whether the samples were taken from adjacent or composite sections. The slice number from which tissue sections are taken should be part of the gross report for lumpectomy or excisional specimens. For mastectomy specimens, adding the location within the breast and the specific aspect of the lesions being sampled is helpful for reconstruction of the sampling process. For example, “A1 = medial to grossly apparent 2:00 lesion, slice 4; A2 = medial aspect of grossly apparent 2:00 lesion, slice 5; A3–7 = composite section from center of 2:00 lesion, slice 6; A8 = lateral aspect of grossly apparent 2:00 lesion, slice 7; A9 = lateral to grossly apparent 2:00 lesion, slice 8.” (See later for a more detailed section on grossing mastectomies.)

Special Scenarios Requiring More Extensive Sampling

Although most grossly obvious breast lesions can follow the previously mentioned tissue sampling procedures, there are many scenarios in which more extensive tissue sampling is required. Some of the more common reasons for more extensive sampling and tissue sampling recommendations for breast surgical specimens are listed in Table 6.4 . In these scenarios, blocking in the entire abnormality is sometimes required. When an expected lesion is vaguely defined or not frankly apparent grossly, more extensive sampling can help ensure that it is appropriately sampled. Alternatively, tissue sampling can occur in more than one round after histological examination of initial sections, but this may slow turnaround time and requires careful preservation of the sectioned specimen orientation.

Invasive lobular carcinomas are often more extensive than expected by imaging or gross examination; therefore, they also require sampling beyond the expected area to ensure accurate extent measurements and margin status ( Fig. 6.4 ). Other forms of invasive carcinoma can be similarly subtle.

Larger areas of in situ carcinoma should also be submitted in near entirety because small foci of invasion can be present anywhere within the span of in situ disease (and may not be grossly apparent). CAP recommends that “for specimens with a known diagnosis of DCIS (e.g., by prior core needle biopsy), it is highly recommended that the entire specimen is examined with serial sequential sampling to exclude the possibility of invasion, to completely evaluate the margins and to aid in determining extent.” However, CAP also acknowledges that it may be impractical to entirely submit larger specimens and recommends that “at least the entire region of the targeted lesion should be examined microscopically.”

After neoadjuvant chemotherapy, the extent of the residual disease can alter prognosis dramatically and help determine whether there will be consideration for additional therapies. When there is obvious residual mass-forming invasive carcinoma, samples can be taken in the traditional manner described earlier. However, increasingly there is minimal residual or no residual disease present. Many protocols, such as MD Anderson Cancer Center’s Residual Cancer Burden calculator, recommend submission of the entire tumor bed (when feasible) to determine additional aspects such as overall cellularity of the residual tumor.

Recently, recommendations on tissue sampling after neoadjuvant chemotherapy were published. These recommendations suggest sampling at least an entire cross section per centimeter over the span of the original pretreatment cancer and creating a map of tissue submitted to report the following elements: (1) span of residual carcinoma, (2) size of largest single contiguous focus of invasive carcinoma, and (3) overall cellularity. Often what was once a single large area of invasion becomes multiple separate smaller foci within the tumor bed. The American Joint Committee on Cancer (AJCC) staging system recommends that postneoadjuvant cases be staged with the “y” prefix and, if there are multiple discrete residual foci of disease, that the ypT stage reflect the size of the largest single remaining focus. If there are multiple foci, the (m) modifier is also used to indicate there were multiple lesions present. See Chapter 28 and Fig. 6.5 for a diagram of how a postneoadjuvant case should be handled.

Representative Sections of Nonlesional Tissue

Representative sections of uninvolved breast tissue or tissue in a prophylactic mastectomy should be included to document nonpalpable lesions. The focus of sectioning should be on fibrous breast tissue only, because it is unlikely to find any clinically useful lesion in pure adipose tissue. Such sections tend to process poorly, often leading to unnecessary expense of time and other resources. The rate of surgically significant lesions in these representative sections is reported to be around 5% to 10%.