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.
Arora
Nimmi
N
Department of Surgery, New York Presbyterian Hospital-Cornell, 525 E. 68th St., New York, NY 10065, USA. nsk2002@med.cornell.edu
Turbendian
Harma K
HK
Kato
Meredith A
MA
Moo
Tracy A
TA
Zarnegar
Rasa
R
Fahey
Thomas J
TJ
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