Kt. Mai et al., Immunostaining for Ret oncogene proteins in papillary thyroid carcinoma: Acorrelation of Rret immunoreactivity and potential of lymph node metastasis, THYROID, 11(9), 2001, pp. 859-863
Ret oncogenes, particularly Ret/PTC, have been associated with the potentia
l of local invasion of papillary thyroid carcinoma (PTC). The purpose of th
is study was to investigate the correlation between the Ret oncogene expres
sion and the potential of lymph node metastasis of PTC. A total of 107 PTC
were microscopically reviewed to identify areas of infiltrating carcinoma (
IC). IC was defined as tumor cells disposed in a haphazard pattern and in l
obules, nests, follicles, or single cells within a desmoplastic or scleroti
c stroma. All cases were submitted to immunostaining for Ret oncogene. Ther
e were 36 noninfiltrating PTC with lymph node metastasis in 1 case and 71 i
nfiltrating FTC with lymph node metastasis in 40 cases. For non-PTC, the po
sitive immunoreactivity was often weak to moderate and focal. For infiltrat
ing PTC with IC, the IC displayed strong immunoreactivity. The noninfiltrat
ing component of PTC with IC usually showed stronger reactivity than PTC wi
thout an infiltrating component. Furthermore, 36 of 40 metastatic PTC in ly
mph node were immunoreactive. Three follicular adenomas with areas of scar
caused by fine-needle aspiration biopsy were not immunoreactive for Ret. In
view of the high potential of infiltrating PTC for lymph node metastasis,
distinction of this type of carcinoma from its noninfiltrating form is clin
ically important. Because immunoreactivity for Ret is usually positive in a
reas of infiltrating PTC and is often negative or focally positive in nonin
filtrating PTC, immunostaining for Ret is helpful to identify infiltrating
PTC and distinguish it from changes caused by fine-needle aspiration ration
biopsy in benign thyroid lesions.