Papillary thyroid carcinoma and microcarcinoma: is there a need to distinguish the two?
BACKGROUND
The clinical significance of papillary thyroid microcarcinoma (PTMC) tumors < or =1 cm is widely debated. The objective of this study was to compare conventional papillary thyroid carcinoma (PTC) (tumors >1 cm) to PTMC and assess for differences in tumor characteristics and patient outcome.


METHODS
A retrospective chart review of patients with PTC or PTMC who were followed for a minimum of 3 years postoperatively and managed at a single academic institute was performed.


RESULTS
Of 202 patients in the study, 66 (32.7%) had PTMC and 136 (67.3%) had conventional PTC. Patient and tumor characteristics including tumor multifocality, extrathyroidal extension, angiolymphatic invasion, and lymph node metastasis were similar between both groups. Twenty-one percent of the PTMC tumors were discovered incidentally. Patients with conventional PTC were significantly more likely to undergo treatment with radioactive iodine therapy compared to PTMC patients (86.4% vs. 66.7%, respectively, p < 0.003). Disease recurrence was observed in 40 patients and was not statistically different between the two groups; 11 (16.7%) in PTMC and 29 (21.3%) in conventional PTC, p = 0.57. Within the PTMC group, tumors of patients that recurred were significantly larger than those who remained disease free (8.1 mm vs. 6.4 mm, p < 0.05). None of the patients with incidental PTMC had disease recurrence. Angiolymphatic invasion was the only significant prognostic indicator of recurrence on multivariate analysis (p < 0.02).


CONCLUSIONS
Nonincidental PTMC can have aggressive tumor features and disease recurrence similar to conventional PTC. These tumors should be managed like any other papillary thyroid malignancy.
Department of Surgery, New York Presbyterian Hospital-Cornell, 525 E. 68th St., New York, NY 10065, USA. nsk2002@med.cornell.edu
Nimmi
N
Arora
Harma K
HK
Turbendian
Meredith A
MA
Kato
Tracy A
TA
Moo
Rasa
R
Zarnegar
Thomas J
TJ
Fahey
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000145:classification / Q000175:diagnosis* / Q000556:secondary / Q000628:therapy; D002291:Carcinoma, Papillary / Q000145:classification / Q000175:diagnosis* / Q000556:secondary / Q000628:therapy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D016015:Logistic Models; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D009626:Terminology as Topic; D013964:Thyroid Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000556:secondary / Q000628:therapy; D013965:Thyroidectomy; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
D007457:Iodine Radioisotopes