Follicular carcinoma of the thyroid with poorly differentiated component presenting with an ileal osteoblastic metastasis.

A 4-year old history of left hip pain brought a 41-year-old women to the surgery clinic where an osteoblastic tumor in the ileum and a thyroid nodule were diagnosed. Incisional biopsy of the ileal lesion showed a metastatic carcinoma, possibly with neuroendocrine differentiation. The thyroid nodule was a follicular carcinoma with progression to insular carcinoma. In retrospect the histologic aspect of the ileal metastasis was identical to that of the insular areas in the thyroid carcinoma. In summary, a patient is described with an osteoblastic metastasis, derived from the insular component of a dedifferentiated follicular carcinoma of the thyroid.