Papillary thyroid carcinoma (PTC) is usually indolent; however, some rare subtypes of PTCs, such as columnar cell and hobnail subtypes, carry poor prognosis as an intermediate malignancy between differentiated carcinoma and anaplastic carcinoma. We present the case of a 56‐year‐old Japanese woman having PTC with aggressive behavior showing characteristic histological features of a predominantly fused follicular and focally solid (FFS) pattern. The fused follicular pattern is cribriform‐like without intermingled vessels. This PTC with FFS pattern included frequent mitotic figures, necrosis, lymphovascular invasion, and metastases with high clinical stage. The tumor cells were broadly positive for antibodies to TTF‐1, PAX8, and bcl‐2, and negative for cyclin D1. Ki‐67 labeling index was approximately 10%, and there was occasional positivity of p53. Targeted next generation sequencing analysis only detected a NRAS mutation (Q61K); there was no mutation and no translocation of other genes including BRAF and RET/PTC. To our knowledge, this is first report that PTC shows aggressive FFS growth pattern. The tumor is possibly included in the new category of differentiated high‐grade thyroid carcinoma in the World Health Organization 2022 classification, or in a novel subtype of PTC owing to its characteristic histological feature and intermediate malignancy between differentiated carcinoma and anaplastic carcinoma.

We present the case of a patient with low-grade non-intestinal-type adenocarcinoma (non-ITAC) of the nasal cavity, which is a very rare tumor. A 62-year-old female visited another hospital due to nasal obstruction on the left side. Adenocarcinoma of the nasal cavity was suspected, and she visited our department for detailed examination and treatment. A tumor was observed from the left inferior meatus to the common nasal meatus. Contrast-enhanced CT/MRI showed a neoplastic lesion with a mild contrast-enhancing effect localized in the nasal cavity. Under the diagnosis of left nasal adenocarcinoma cT1N0M0, we performed endoscopic tumor resection under general anesthesia. Histopathologic examination of the tumor showed low-grade non-ITAC. The margins were negative and no additional treatment was performed. No local recurrence or metastasis was observed 12 months postoperatively.

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We examined 365 patients who underwent surgery for thyroid lesion at our institution during the nine years from July 2012 to September 2021. There were 112 benign lesions and 253 malignant tumors. The accurate diagnosis rate of fine-needle aspiration cytology (FNAC) was 91.7％ . 76.4％ of Class 3 cases that received FNAC were malignant tumors. Postoperative recurrent laryngeal nerve palsy (RLNP) was observed in 20 case, of which 16 case were transient and 4 case were permanent. We examined the postoperative complications of RLNP regarding factors of age, gender, surgical side, histological type, the presence or absence of cervical lymph node dissection, and size. The frequency of RLNP increased in cases who were 55 years old and over, bilateral side, malignant tumor and cervical lymph node dissection.