An understanding of the normal surgical thyroid anatomy is a requisite for accurate gross characterization of lesions. The fundamentals of thyroid anatomy are described in Chapter 1. These principles can be applied in a practical sense to the thyroid specimens that are commonly encountered at the gross bench. For neoplasms, many components of the gross examination are incorporated into tumor staging (see Chapter 7). A sample structured format for thyroid gross description is presented in Table 19.1.

Certain parameters are universal to all gross specimens.¹,²,³,⁴,⁵ First of all, the appropriate patient identification information and labeling should be confirmed. In addition, the “state” of the specimen (whether it is received unfixed, in saline or in formalin) on receipt should be documented as this may preclude ancillary molecular or flow cytometric studies. It is standard of care to provide overall specimen measurements along the X, Y, and Z axes in centimeters, and in the case of endocrine organs such as the thyroid, specimen weight in grams. These parameters not only are part of the documentation of the patient’s procedure but also serve as the first indicators of a pathologic process.

Another key component of the thyroid gross examination is the identification of specimen type.¹,²,³,⁴ The proper orientation of a specimen based on anatomic and surgical landmarks provides a contextual framework for subsequent description of lesions. It allows for meaningful clinical and radiographic correlation and
serves as a quality assurance checkpoint. The common thyroid specimens received for pathologic examination are as follows: the lobectomy, which consists of a thyroid lobe, often with some portion of the isthmus; and the total thyroidectomy, which contains the entire thyroid. The term near-total thyroidectomy is often used to describe specimens that consist of a thyroid lobectomy, isthmus, and a portion of the contralateral lobe with about 1 to 2 g of tissue left in the patient.⁵,⁶ Occasionally, for locally aggressive processes, thyroidectomy specimens may be extended to include contiguous skeletal “strap” muscle and/or lymph node compartments. Other specimen types that may be encountered include excisions of substernal goiter. Intentional enucleation of nodules is no longer a standard practice, and these specimens will rarely be encountered, if at all.

The correct orientation of a thyroidectomy can be ascertained in most cases in which the specimen is received intact. The surgeon may mark the superior pole of the thyroid with a suture or clip. This may be the only landmark for orientation in a severely distorted specimen. However, the orientation of most thyroidectomy specimens is readily apparent by gross examination even without a suture. This visual orientation should be performed even if the specimen is oriented by the surgeon, since sutures and clips may migrate and detach or even be incorrectly placed initially. In most situations, the superior pole of each thyroid lobe is longer and more tapered as compared with the rounded, bulbous inferior pole (Fig. 19.1A). The isthmus connecting the two lobes is typically situated inferiorly as well. The anterior surface of the thyroid is typically more convex and raised, whereas the posterior surface, which sits along the trachea, is more concave. The convergence of these surfaces results in a fairly sharp protuberant lateral border (Fig. 19.1B). Occasionally, the underlying pathologic process distorts the native contour of the thyroid gland to the point where orientation is very difficult or perhaps impossible. In these cases, orientation may still be salvaged, since the lateral border and superior poles of a lobe are more likely to retain their anteroposterior concave-convex configuration, even if the majority of the thyroid is massively distorted by a lesion (Fig. 19.1C). An additional gross clue in lobectomy specimens distorted by a lesion is the identification of roughened transected surface (typically with cautery) or fibrosis (from the site of prior surgery in a completion lobectomy specimen) as this would indicate isthmus where the specimen was transected (Fig. 19.1D). Finally, in extremely distorted specimens, if the location of a particular lesion is known based on imaging studies, the specimen can be oriented using the lesion as a landmark. For instance, if a dominant cystic nodule is noted inferiorly in the right lobe on ultrasound, once this lesion is identified in the specimen, it can be used to mark the right inferior pole.