Pitfalls

Follicular Cells Nuclear Grooves

Nuclear enlargement is an important diagnostic feature of PTC, but nuclear size alone cannot be used to diagnose PTC because follicular cells in other thyroid lesions can also have enlarged nuclei. Because of its enlarged nuclei and variable grooves, Hurthle cell lesions, particularly those associated with Hashimoto's thyroiditis, are included in the differential diagnosis of PTC. However, in contrast to the nuclei of PTC, the nuclei of Hurthle cells are typically round, rather than oval, and...

Blood Elements And Foamy Macrophages In Thyroid Cyst

Algorithmic approach to cystic lesions. obtaining a sample from the solid portion of a thyroid cyst. For most types of cysts, both benign and malignant, the microscopic features of the cyst contents are similar and include a combination of abundant hemosiderin-laden macrophages, foamy histiocytes, blood, proteinaceous debris, watery colloid, and giant cells with foamy cytoplasm (Figure 8.2). Cholesterol crystals may also be present and are best visualized using Diff-Quik stains. The...

Follicular Cells

The follicles within a normal thyroid gland range from 50 to 500 mm in diameter (Figure 5.5). In adenomatous nodules, the follicles are often much larger and are called macrofollicles. A macrofollicular architectural pattern often accompanies colloid-predominant aspirates and is a key feature of benign thyroid nodules. Because the internal diameter of fine needles is typically less than 300 mm, these abnormally enlarged macrofollicles are fragmented as they enter the needle. Cyto-logically, the...

Thyroglossal Duct Cysts

Thyroglossal duct cysts occur from embryologic remnants of the thyroglossal duct, a midline structure associated with the hyoid bone. Although more common in childhood, they can also occur in adults. The fluid often has a mucinous appearance, but it can also be proteinaceous. In contrast to thyroid cysts, however, the fluid seldom has hemorrhagic features and colloid is absent. Aspirates of thyroglossal duct cysts can have a predominance of macrophages and background debris, but they are often...

Reidels Thyroiditis

Riedel Thyroiditis

Aspirates of Reidel's thyroiditis are hypocellular and often unsatisfactory for evaluation due to scant cellularity. Microscopically, fragments of collagenous fibrous tissue, scattered cytologically bland spindle cells with plump elongate nuclei, and some background chronic inflammatory cells are seen (Figures 4.9, 4.10). Follicular cells, lymphohistiocytic aggregates, and abundant lymphocytes are absent, helping to exclude chronic lymphocytic thyroiditis. Cytologic Features of Reidel's...

Cellular Adenomatous Nodule

Aspirates of thyroid nodules composed of follicular cells arranged in a predominantly macrofollicular pattern and lacking nuclear features of PTC are benign, and we diagnose them as adenomatous nodules (Figures 6.2-6.9). A variety of Figure 6.2. Adenomatous nodule. These nodules are characterized by a predominance of macrofollicles such as the one shown here. During smear preparation, watery colloid is extruded from the macrofollicle into the background. (Smear, Papanicolaou.) Figure 6.2....

Suspicious for a Follicular Neoplasm

The group of aspirates diagnosed as suspicious for a follicular neoplasm includes both follicular adenomas and FC. Aspirates are cellular and are characterized by follicular cells arranged in any of three patterns microfollicles, trabeculae, or crowded three-dimensional groups (Figures 6.14, 6.15, 6.16). Aspirates with a combination of these patterns can also be seen. This approach to diagnosing follicular lesions works because FCs are virtually never predominantly composed of normal-sized...

Differential Diagnosis and Pitfalls

Colloid Parathyroid Adenoma

Problems may arise in diagnosing adenomatous nodules when they are cellular, but careful attention to the macrofol-licular arrangement of cells will avoid calling the aspirate a follicular neoplasm. As alluded to previously, a variety of changes including Hurthle cells, mild nuclear atypia, meta-plastic squamous cells, or spindle-shaped cells can be seen in aspirates of adenomatous nodules. In particular, the presence of spindle cells and metaplastic squamous cells can raise the possibility of...

Cell Blocks and Cytospins

In the case of cystic lesions that yield larger volumes, we put a small sample onto slides for direct smears as previously described, but then reserve the remainder for thin-layer preparations, cytospins, or a cell block. We do not routinely prepare cell blocks unless it is likely that we will need to perform immunocytochemistry (e.g., for suspected medullary carcinoma). In this case, we often perform two or three extra passes and place the entire specimen into Hanks balanced salt solution for...

Subacute Thyroiditis

Aspirates of subacute thyroiditis are usually hypocellular and consist of multinucleated giant cells that surround and engulf colloid. In addition, loose aggregates of epithelioid histiocytes (granulomas) are characteristic (Figures 4.7,4.8). Care should be taken not to misinterpret the epithelioid histiocytes with their curved nuclei and abundant granular cytoplasm as an epithelial neoplasm. A variable amount of background mixed inflammatory cells including lymphocytes, plasma cells,...

Graves Disease

Graves' disease (diffuse toxic goiter) is a diffuse hyperplastic autoimmune thyroid disorder of middle-aged women who typically present with hyperthyroidism. It is usually diagnosed clinically, and thus is seldom sampled by FNA except when a dominant cold nodule is present. Aspirates are hypercellular and contain follicular cells in large branching sheets as well as in microfollicles in a background of abundant pale watery colloid (Figures 6.11, 6.12). Follicular cells have moderate amounts of...

Nuclear Grooves and Pseudoinclusions

The presence of extensive nuclear grooves is a common finding in PTC, caused by an infolding of the nuclear membrane. Nuclear grooves are present in nearly all cases of PTC, but they may be sparse in up to 25 of cases. They are often parallel to the long axis of the oval nuclei, giving a coffee bean appearance (see Figure 9.5). Nuclear grooves alone are nonspecific and can be seen in a variety of neoplastic and non-neoplastic cells, including macrophages and benign follicular cells. However,...

Diagnostic Categories

Next, the FNA should be assigned to a diagnostic category Unsatisfactory, Nondiagnostic, Benign, Suspicious, or Malignant, based on the diagnostic criteria discussed in subsequent chapters Table 3.2 . Because of the spectrum of categories and diagnoses utilized by pathologists, communication with clinicians is essential to ensure optimal patient management. Less Than Optimal Satisfactory Category Unsatisfactory Nondiagnostic Benign Malignant Suspicious Diagnosis See Table 3.2 Comment...

Branchial Cleft Cysts and Ultimobranchial Body Cysts

Ultimobranchial Cyst

Branchial cleft-like cysts lymphoepithelial cysts and ulti-mobranchial body cysts cystic solid cell nests are rare in the thyroid gland, and when they do occur it is often in association with Hashimoto's thyroiditis. Aspirates of branchial cleft cysts of the neck and branchial cleft-like cysts of the thyroid are similar and contain turbid proteinaceous fluid and degenerate squamous cells, as well as glandular cells that may be mucin containing or ciliated.Variable amounts of background...