Papillary microcarcinoma

Abstract

Background: Papillary microcarcinoma (PMC) is increasing in incidence because of diagnosis by ultrasound-guided fine-needle aspiration cytology.

Methods: Between January 1966 and December 1995, we treated 6019 patients with papillary cancer; among them, 2070 patients with PMC were studied.

Results: PMC is essentially very similar to papillary cancer that is 11 mm or larger and has a very good prognosis. Smaller tumors and younger patients have a better prognosis. Among PMC, larger tumors (6-10 mm) recur in 14% at 35 years compared with 3.3% in patients with smaller tumors. Patients older than 55 years have recurrence in 40% at 30 years, with a worse prognosis than younger patients who have a recurrence rate of less than 10%. Extracapsular invasion by the primary tumor also has a higher recurrence rate. The majority of recurrences are in the neck. Therefore, annual ultrasound of the neck is effective for recurrence surveillance.

Conclusion: Papillary microcarcinoma is similar to larger papillary carcinomas with tumor characteristics and age-based recurrence rate that extends for many years, justifying long surveillance after surgery.

Fig. 1

Recurrence-free survival rates versus patient age between 1966 and 1995. Age was a significant factor in recurrence-free survival by single-variable analysis

Fig. 2

Recurrence-free survival rates by size of tumor. Tumors up to 5 mm showed significantly better recurrence-free survival rates 35 years after surgery than tumors between 6 and 10 mm

Fig. 3

Recurrence-free survival rates of patients with autoimmunity. Patients with autoimmune thyroid diseases such as Graves’ disease and Hashimoto’s disease had significantly better prognosis 35 years after surgery than patients without an autoimmune disease

Fig. 4

Recurrence-free survival rates of patients with preoperative diagnosis. Patients preoperatively diagnosed with benign nodules had significantly better prognosis 35 years after surgery than patients preoperatively diagnosed with malignant tumors. Patients whose tumors were not preoperatively identified had the best prognosis

Fig. 5

Recurrence-free survival rates of patients with primary tumor adherent to the recurrent nerve. Patients with documented invasion to the recurrent nerve had significantly worse recurrence-free survival than patients with no documented invasion to the recurrent nerve

Fig. 6

Recurrence-free survival rates of patients with primary tumor adherent to the esophagus. Patients with documented invasion of the esophagus had significantly worse recurrence-free survival than patients with no documented invasion of the esophagus

Fig. 7

Patients with documented gross nodal metastases had significantly worse recurrence-free survival than patients with no documented gross nodal metastases

Fig. 8

Numbers of nodal metastases in recurrence-free survival rate. Patients with a large number of nodal metastases had significantly worse recurrence-free survival than patients with fewer nodal metastases

Fig. 9

The interval between primary surgery and the first recurrence. Recurrence was seen in 73 patients (3.5%) over a 35-year period. Among them, 68 patients experienced recurrence in the thyroid bed and/or cervical lymph nodes. One patient had recurrence in the lung, four patients in bone, and one patient in multiple sites. Median interval between primary surgery and first recurrence was 10.29 years. The box represents the median quartile, the diamond represents the average, and the bracket represents the short half

Fig. 10

The interval between primary surgery and the second recurrence. A second recurrence was seen in 12 patients (0.6%) over a 35-year period. Four patients had recurrence in the lung, one patient in bone, and one patient in the mediastinum. The box represents the median quartile, the diamond represents the average, and the bracket represents the short half