Papillary thyroid cancer is the most common type of thyroid cancer in America, but not worldwide. It occurs more frequently in women and presents in the 30-40 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 (in this group, the cancer tends to be multifocal with early lymphatic spread, and portends a relatively poor prognosis).

Markers

Thyroglobulin can be used as a tumor marker for well-differentiated papillary thyroid cancer.

Pathology

• Characteristic Orphan Annie eye nuclear inclusions (nuclei with uniform staining, which appear empty) and psammoma bodies on light microscopy. The former is useful in identifying the follicular variant of papillary thyroid carcinomas.
• Lymphatic spread is more common than hematogenous spread
• Multifocality is common
• The so-called Lateral Aberrant Thyroid is actually a lymph node metastasis from papillary thyroid carcinoma.

Prognosis

There are at minimum 13 known scoring systems for prognosis; among the more often used are:

• AGES - Age, Grade, Extent of disease, Size
• AMES - Age, Metastasis, Extent of disease, Size
• MACIS - Metastasis, Age at presentation, Completeness of surgical resection, Invasion (extrathyroidal), Size (this is a modification of the AGES system)
• TNM - Tumor, node, metastasis. Remarkable about the TNM grading for (differentiated) thyroid carcinoma is that the scoring is different according to age.

Treatment

Surgical treatment:

• Minimal disease (diameter up to 1.0 centimeters) - hemithyroidectomy (or unilateral lobectomy) and isthmectomy may be sufficient. There is some discussion whether this is still preferable over total thyroidectomy for this group of patients.
• Gross disease (diameter over 1.0 centimeters) - total thyroidectomy, and central compartment lymph node removal is the therapy of choice. Additional lateral neck nodes can be removed at the same time if an ultrasound guided FNA and thyrobulin TG cancer washing was positive on the pre-operative neck node ultrasound evaluation.

Arguments for total thyroidectomy are:

• Reduced risk of recurrence, if central compartment nodes are removed at the original surgery.
• Papillary carcinoma is a multifocal disease (hemithyroidectomy may leave disease in the other lobe)
• Ease of monitoring with thyroglobulin (sensitivity for picking up recurrence is increased in presence of total thyroidectomy, and ablation of remnant normal thyroid by low dose radioiodine 131 after following a low iodine diet (LID).
• Ease of detection of metastatic disease by thyroid and neck node ultrasound.

Thyroid total body scans are less reliable at finding recurrence than TG and ultrasound.

Additional images

References