Papillary thyroid cancer (papillary thyroid carcinoma, PTC) is the most common type of thyroid cancer, representing 75 percent to 85 percent of all thyroid cancer cases. It occurs more frequently in women and presents in the 20–55 year age group. It is also the predominant cancer type in children with thyroid cancer, and in patients with thyroid cancer who have had previous radiation to the head and neck. It is often well-differentiated, slow-growing, and localized, although it can metastasize.

Papillary thyroid carcinoma is usually discovered on routine examination as an asymptomatic thyroid nodule that appears as a neck mass. In some instances, the mass may have produced local symptoms. This mass is normally referred to a fine needle aspiration biopsy (FNA) for investigation. FNA accuracy is very high and it is a process widely used in these cases. Other investigation methods include ultrasound imaging and nuclear scan. The ultrasound is a useful test to distinguish solid from cystic lesions and to identify calcifications. The thyroid ultrasound is also very effective to discover microcarcinomas, which refer to very small carcinomas (<1 cm).

Papillary thyroid carcinomas are also discovered when a hard nodule is found in multinodular goiter, when enlarged cervical lymph nodes are detected, or when there are unidentified metastatic lesions elsewhere in the body. Expanding lesions found in the thyroid gland, especially if they are painful, should be examined as they may indicate the presence of papillary thyroid carcinoma. Other clinical signs that could indicate papillary thyroid are fixation to the trachea, a firm neck mass, damage to recurrent laryngeal or cervical sympathetic nerves. Five percent of the population can have thyroid nodules, and the majority will be benign.

Appropriate workup includes an ultrasound of the neck, followed by lab studies. Patients will usually meet with both an endocrinologist and a surgeon (head and neck surgeon or endocrine surgeon).

Thyroglobulin can be used as a tumor marker for well-differentiated papillary thyroid cancer. HBME-1 staining may be useful for differentiating papillary carcinomas from follicular carcinomas; in papillary lesions it tends to be positive.

Reduced expression of ATP5E is significantly associated with the diagnosis of papillary thyroid cancer and may serve as an early tumor marker of the disease. Serum microRNAs have shown good diagnostic performance for distinguishing patients with papillary thyroid cancer from patients with benign thyroid nodules and healthy controls, and are suggested as novel and minimally invasive diagnostic approach in clinical practice.

Papillary thyroid cancer gets its name from the papillae among its cells, visible on microscopy. Features include:

Several variants are recognized, although classic papillary thyroid carcinoma is the most frequent: microscopic-follicular variant, diffuse-sclerosing variant, tall-cell variant, columnar-cell variant, hobnail variant, and others. The encapsulated-follicular variant, specifically when noninvasive, has been newly reclassified as the noninvasive follicular thyroid neoplasm with papillary-like nuclear features.