Poorly differentiated (insular)
carcinoma of the
thyroid gland is rare and defined as follicular-
cell neoplasms that show limited evidence of structural follicular
cell differentiation and occupy both morphologically and behaviourally an intermediate position between differentiated (follicular and
papillary carcinomas) and undifferentiated (anaplastic)
carcinomas. The authors
report a case of a 37-year-old
Thai woman who presented with a prolonged left
thyroid nodule. Final pathological
diagnoses of her mass were poorly differentiated (insular)
carcinoma with lymphovascular invasion and
nodular goiter. The
tumor cell arrangements were nest (insular) and trabecular patterns with some follicular formations.
Immunohistochemistry of the
tumor cells revealed negative immunostaining for OCT4. Expression of OCT4
gene is involved in the
regulation and
maintenance of pluripotency of
embryonic stem cells,
germ cells, and in
tumor cells. The authors believe that poorly differentiated (insular)
carcinoma of the
thyroid gland probably develops from the remnant of
thyroid stem cells and is not associated with dedifferentiation (
anaplasia or loss of cellular differentiation) from
nodular goiter or
cells of other
thyroid carcinomas. Although there was negative immunostain for OCT4 in the presented case, the authors assumed that the
tumor cells behave with an intermediate position between
thyroid stem cells and prothyrocytes Also they do not behave with thyroblasts. Additionally, the
tumor may be associated with new cellular dedifferentiation. However, there is only one case of
immunohistochemistry of OCT4 in poorly differentiated (insular)
carcinoma of the
thyroid gland. Thus,
prognosis of the presented still is mainly correlated with clinical and histological findings. Further
research on expression of OCT4
gene on
thyroid cancers and other malignant
tumors relating to tumorigenic
cancer cells (
cancer stem cells) may be useful to prognostic evaluation and
administration of a new
chemotherapy and/or
radiotherapy that is specific for
tumor-initiating
cells.