2021 Volume 20 Issue 1 Pages 35-40
An 84-year-oldfemale hadundergone left hemithyroidectomy for left papillary thyroidcancer 6 years before. She presentedwith a nodule on the right clavicle for 2 months. A clinical investigation revealeda 9×7 mm-sized, light-red, dome-shaped nodule on the right clavicle. Dermoscopy demonstratedarborizing vessels. A biopsiedspecimen demonstrateda well-demarcatedbasophilic nodule in the dermis and deeper. There were atypical columnar cells with oval, hyperchromatic nuclei andample cytoplasm, arrangedin a papillary or tubular fashion. Immunohistochemically,tumor cells were positive for cytokeratin 7, thyroidtranscription factor-1 (TTF-1), andPAX8, and were negative for CEA andGCDFP-15. The present case was diagnosedas metastatic carcinoma of the skin from papillary thyroidcancer. Several transcription factors have been reportedto be useful as specific markers in a variety of internal carcinomas. In the present case, the co-expression of TTF-1 andPAX8 enabledthe diagnosis of papillary thyroidcancer. A skin biopsy is a useful tool in investigating the origin of metastatic carcinomas of the skin, leading to the choice of appropriate treatment. Skin Research, 20 :35-40, 2021
