Response to Malhotra et al.

Abstract

We are writing regarding a recent article entitled ‘‘Renal Metastasis from Hurthle Cell Thyroid Carcinoma and Its Evaluation with Hybrid Imaging’’ by Djekidel et al. (1). We agree with the authors’ point regarding the rarity of renal involvement from primary cancers of the thyroid. In our recently accepted article, however, a literature search revealed that renal metastases from a primary thyroid cancer have been reported in about 20 patients to date (2). This is contrary to the authors’ claim that these metastases have been reported in only 10 patients. Another pertinent reference describing single photon emission computed tomography-computed tomography evidence for renal metastasis from follicular thyroid cancer should also be noted (3). Second, Marino et al. (4) have reported a rare case of renal metastasis from thyroid carcinoma that started as Hurthle cell adenoma and transformed into a carcinoma with a follicular appearance after 26 years. Hence, this may not be the first case of Hurthle cell cancer with renal metastases. Third, we were surprised to find that multiple lesions that showed F-18 fluorodeoxyglucose uptake were not thought to show iodine concentration. Perhaps, a small amount of abnormal uptake could have been missed on the radioiodine scan. In the literature and from our institutional experience of treating advance metastatic thyroid cancer, we find that many such lesions show both fluorodeoxyglucose and iodine avidity. Hence, they are amenable to administration of radioiodine therapy, in high doses of 200–250 mCi, with intent to palliate. Many such patients have dramatic symptomatic relief and good quality of life despite harboring multiple metastases.