Clinical characteristics and prognosis of 80 patients (53 women and 27
men) with sporadic medullary thyroid carcinomas (MTC), less than 1 cm
in size (micro-MTC), operated on between 1971 and 1996 are reported (
73 total and 7 partial thyroidectomies). These patients, obtained from
a national database of 899 patients with MTC, were compared with 357
cases of sporadic MTC greater than 1 cm and 149 subjects with familial
MTC less than 1 cm (familial micro-MTC). Median age at surgery was 52
.5 years, a distribution similar to larger sporadic MTC. Micro-MTC was
identified due to elevated calcitonin (47.5%), clinically identified
lymph node (10.0%.), distant metastases (6.3%) or pathologic finding a
t surgery (36.2%). Diarrhea and/or flushing were observed in 6 patient
s including 4 with clinically identified lymph node. Among patients wh
o had lymphnode dissection at surgery (68.8%), lymph node involvement
with tumor was observed in 30.9%, and was significantly more frequent
in multifocal (7/11) than in unifocal micro-MTC (p < 0.03). All sporad
ic micro-MTC were unilateral. Survival rate was 93.9% +/- 4.4% (SE) at
10 years, greater than that observed in sporadic macro-MTC (p = 0.04)
. Normal postoperative basal calcitonin (CT) was obtained in 71.1% of
micro-MTC patients versus 33.6% in sporadic macro-MTC (p < 0.01). Spor
adic micro-MTC is much more frequent than expected, 15% of MTC in our
series. Although specific survival rate and percentage of biological c
ure in micro-MTC are significantly better than for larger tumors, the
frequency of lymph node involvement, however, justifies an aggressive
surgical approach including total thyroidectomy and bilateral central
lymph node dissection.