Papillary Thyroid Cancer: Rare Case of Anaplastic Transformation in Mesentery Metastases
Posted: Wednesday, October 7, 2020
Although anaplastic transformation of papillary thyroid cancer tends to occur either in the thyroid itself or within regional lymph nodes, a rare case illustrated it also may occur in the mesentery sites of metastases. In this case report, published in Surgical Case Reports, Harutsugu Sodeyama, MD, of the Japanese Red Cross Society Nagano Hospital, and colleagues demonstrated the utility of an appropriate biopsy and paired-box gene 8 (PAX8) immunostaining in confirming this diagnosis.
“Such a disease is difficult to diagnose based only on the expression of PAX8, and it is important to rule out other cancer types by histological examination or image-based findings,” they commented.
A 74-year-old man, with a history of papillary thyroid carcinoma, was admitted to the hospital with abdominal pain. Six years earlier, he had undergone total thyroidectomy and mediastinal lymph node dissection, followed by radioactive iodine therapy for recurrence in the lung 2 years after the initial surgery.
When admitted, the patient had renal dysfunction as well as an elevated white blood cell count and C-reactive protein levels. A large intra-abdominal mass into the colon and retroperitoneum was seen on CT, as was lymphadenopathy in several para-aortic lymph nodes, suggesting metastases or disease dissemination.
Diagnosed with generalized peritonitis from colon perforation, the patient underwent emergency laparotomy, and a protective ileostomy was necessary. A biopsy specimen revealed the absence of thyroid carcinoma cells, so it was believed to be a primary undifferentiated sarcoma. His general condition deteriorated with the rapid development of systemic metastases. One month after surgery, the patient died.
On autopsy, tumors were found in the mesentery tissue, brain, lungs, para-aortic lymph nodes, liver, small intestine, and bone marrow. Immunohistochemical staining was sporadically positive for PAX8, which is often expressed in thyroid cells. The authors discovered that rather than a sarcoma, it was anaplastic papillary thyroid cancer at a site of metastasis in the soft tissue of the mesentery.
Disclosure: The study authors reported no conflicts of interest.