Innumerable Radioiodine Negative Cutaneous Metastases From Papillary Thyroid Cancer

Abstract

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy and papillary thyroid carcinoma (PTC) accounts for a majority of these. Distant metastases, especially to the lung and bones, occur in about 10% of patients, who can still survive for many years. We report here the case of a 32 year old female who presented with multiple bilateral cervical lymphadenopathy, diagnosed as metastatic PTC on cytology. She underwent total thyroidectomy and bilateral radical neck dissection followed by radioiodine therapy. Subsequently she developed pulmonary and bone metastases, and during the course of successive radioiodine doses, presented with multiple, painless cutaneous and subcutaneous nodules which proved to be metastatic on cytopathology and immunostaining. Radioiodine uptake was not seen in these lesions, suggesting dedifferentiation of follicular cells. This case emphasizes three clinically important issues-firstly, although extremely rare, cutaneous nodules can represent metastatic PTC in patients with pre existing lung and bone lesions and portends a poorer prognosis. Secondly, these lesions may be dedifferentiated and hence not amenable to radioiodine therapy although the bone and lung lesions show radioiodine uptake. SPECT/CT helps us in determining if uptake of 131-I is in the skin lesions or underlying other sites. Redifferentiating agents may play a role in management of such disease. Lastly, immunostaining with CK19 and Thyroglobulin (Tg) can be highly useful to confirm the pathologic diagnosis.




J Endocrinol Metab. 2011;1(5):227-231
doi: https://doi.org/10.4021/jem57w