Collision tumor of a papillary and follicular thyroid carcinoma: a case report.

BACKGROUND: Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are common differentiated thyroid cancers, but the detection of a collision tumor is an extremely rare event. CASE PRESENTATION: The patient was a 69-year-old Japanese female with multiple cervical lymph node swellings and a thyroid tumor. Preoperative fine needle aspiration cytology of the enlarged lymph node revealed a cytological diagnosis of papillary thyroid carcinoma (PTC). A total thyroidectomy, right cervical dissection and paratracheal dissection were performed. Histopathological and immunohistochemical analyses of resected specimens revealed a collision tumor of PTC and FTC. Multiple metastases of papillary carcinoma were found in the dissected lymph nodes. In the PTC lesion, IHC for BRAF (V600E) was positive but negative for the FTC lesion. Genetic analyses further revealed a TERT promoter C228T mutation in PTC and a NRAS codon 61 mutation in FTC. The patient died of recurrent cancer 8 months after surgery. CONCLUSIONS: A case of a collision tumor of PTC and FTC is very rare, and even fewer cases have been subjected to genetic scrutiny. The present case was successfully diagnosed by pathological examination using immunohistochemical and genetic analyses. The TERT promoter mutation in the PTC lesion was consistent with the aggressive behavior of the cancer.

A pediatric case of moderate active ulcerative colitis successfully treated with vedolizumab in Japan.

Corticosteroids and biologics are used to treat moderate-to-severe active pediatric ulcerative colitis (UC); however, it is often difficult to continue administration because of systemic side reactions. Vedolizumab is considered to have few adverse effects due to its mechanism of action and it is expected to be used in children, but the long-term administration of vedolizumab to Japanese pediatric patients with UC has not been reported. We report a case of pediatric moderate active UC with anti-tumor necrosis factor-failure that was successfully treated with vedolizumab in Japan.