[Poorly differentiated "insular" carcinoma of the thyroid: long-term survival]

Poorly differentiated "insular" thyroid carcinoma is a rare, aggressive and often lethal variant of thyroid cancer. Thirty-one cases of this entity were encountered over a 18-yr period. In most of them surgical therapy consisted of total or near-total thyroidectomy. Six patients had distant metastases and/or mediastinal or tracheal infiltration at presentation. Fifteen out of 25 apparently cured after surgery (60%) developed recurrence in the neck and/or distant sites. Radioiodine was employed to destroy thyroid remnants (22 cases) and subsequently to treat persistent/recurrent disease (17 cases). Thirteen patients showed radioiodine uptake in neoplastic lesions and in 3 cases complete resolution was observed. After a mean follow-up of 4.5 years (range 1-16) 6 patients had died of their tumor, 12 are alive with persistent/recurrent disease, 13 do not show any evidence of disease. This experience confirms that "insular" carcinoma tends to have an aggressive behavior, but therapy can be effective. Recognition of this entity is therefore important for planning adequate surgical approach and subsequent patient management.