Thyroid cancer refers to various cancers arising from thyroid gland. Differentiated thyroid cancers (DTCs) include papillary, follicular, and Hurthle cell carcinomas and represent cancers retain normal thyroid functions such as iodine uptake. Radioactive iodine (RAI) is generally used for upfront treatment of metastatic DTCs, but RAI refractory DTCs remain to be clinical challenges. Sorafenib and lenvatinib were approved for the treatment of RAI refractory DTCs and more recently, genomics-based targeted therapies have been developed for NTRK and RET gene fusion-positive DTCs. Poorly differentiated and anaplastic thyroid cancers (ATCs) are extremely challenging diseases with aggressive courses. BRAF/MEK inhibition has been proven to be highly effective in BRAF V600E mutation-positive ATCs and immune checkpoint inhibitors have shown promising activities. Medullary thyroid cancers, which arise from parafollicular cells of thyroid, represent a unique subset of thyroid cancer and mainly driven by RET mutation. In addition to vandetanib and cabozantinib, highly specific RET inhibitors such as selpercatinib and pralsetinib have demonstrated impressive activity and are in clinical use.

Head and neck cancer is the 6^th most frequently diagnosed solid tumor in the world. Alcohol consumption, smoking, and HPV infection are associated with the incidence of head and neck squamous cell carcinoma (HNSCC). Although a multidisciplinary approach is a key strategy for the treatment of locally advanced HNSCC, systemic therapy is the mainstream of recurrent or metastatic HNSCC treatment. Stage IV HNSCC has a relatively poor prognosis with median overall survival of around one year. There have been many clinical trials to investigate the efficacy of target agents in the treatment of HNSCC. In the HPV-negative HNSCC, TP53 and CDKN2A are the most commonly mutated genes. In the HPV-positive HNSCC, the PI3K pathway is frequently altered. EGFR, PI3K, cell cycle pathway, MET, HRAS, and IL6/JAK/STAT pathway are explored targets in HNSCC. In this study, we review the target pathways and agents under research. We also introduce here umbrella trials of recurrent or metastatic HNSCC conducted by the Korea Cancer Study Group. The combination of target agents with immune checkpoint inhibitors or cytotoxic chemotherapies would be a future step in the precision medicine of HNSCC treatment.

Background/Objectives: The aim of this national population-based retrospective study was to analyze the status and treatment outcome in patients with hypopharyngeal cancer. Materials & Methods: Participants were included in the KNHIS national sample cohort who received a KNHIS health check-up in 2008 and 2009, and we followed these individuals until 2017. Patients were defined as having hypopharynx cancer if they had admissions records for hypopharynx cancer in their national health insurance data from 2010 to 2017. Results: The study cohort included 3,922 patients. According to our nationwide data, 3,533(90.1%) were male with a median age of 65.03±11.04 years at the time of diagnosis. Among parametric models for hypopharyngeal cancer prognosis, old age (Hazard ratio [HR]:1.92; 95% confidence interval[CI]:1.76-2.09), female (HR:0.77; 95% CI:0.66-0.89), and low socioeconomic status (HR:1.216; 95% CI:1.114-1.327) were significantly associated with survival. Compared with concurrent chemoradiotherapy, patients who received no treatment (HR, 1.88; 95% CI, 1.31-2.70), neoadjuvant chemotherapy followed by surgery (HR, 1.21; 95% CI, 1.04-1.41), and chemotherapy alone (HR, 1.16; 95% CI, 1.03-1.27) showed poor prognosis in hypopharyngeal cancer. Conclusion: Our data indicated that age, sex, and income were significant predictors of lifetime survival in patients with hypopharyngeal cancer. Treatment modalities were also associated with prognosis. The data have implications for treatment investigations and prevention strategies.

Background/Objectives: Although thyroid lobectomy recently is considered as sufficient for low-risk papillary thyroid carcinoma (PTC), completion thyroidectomy is required due to the insufficiency of the preoperative evaluation. The aim of this study was to investigate recurrence rate and disease free survival depending on the gross extrathyroidal extension (gETE) or the number of metastatic lymph node identified in patients with PTC. Materials & Methods: We assessed 3373 patients with PTC who underwent lobectomy at Seoul St. Mary's Hospital (Seoul, Korea) between January 2009 and December 2014. Clinicopathological characteristics and long-term surgical outcomes were retrospectively analyzed through complete chart reviews. The mean follow-up duration was 97.1 ± 21.4 months. Results: The rate of recurrence was higher in gETE group (1.8% vs. 6.0%, p=0.004), leading to decreased disease free survival in Kaplan-Meier analysis (log-rank p<0.001). N1 group (n=1389) was analyzed into two groups whether the number of positive nodes is more than 5 or less. For the group of the more metastatic nodes, the recurrence rate higher compared to the other group (3.0% vs. 9.3%, p<0.001). DFS was longer in the group that had lesser metastatic nodes (log-rank p<0.001). However, in terms of N1 group over 1cm (n=492), No statistical difference was observed according to the number of positive lymph nodes (4.5% vs. 9.1%, p=0.092) Conclusion: When it comes to node positive PTC, Despite the number of positive lymph nodes was over 5, follow-up with no further surgery can be an option.

Background/Objectives: Extra-nodal extension (ENE) is one of the strongest prognosticators in oral cancers. Here we tried to evaluate clinicopathological factors associated with the presence of ENE. Materials & Methods: We retrospectively analyzed clinical information of 120 patients who diagnosed with oral cancer and received curative surgery at our hospital from Mar 2012 to Apr 2020. We comparatively analyzed clinicopathological factors associated with the presence of lymph node (LN) metastasis and ENE, respectively. Results: Variable factors of primary tumor characteristics such as lymphovascular invasion, perineural invasion, largest diameter of tumor, depth of invasion and maximum standardized uptake value were significantly associated with the presence of cervical LN metastasis. The largest diameter of tumor was statistically significant also in multivariate analysis for predicting the LN metastasis. Meanwhile, the association between primary tumor characteristics and the presence of ENE were not statistically significant except the primary tumor size. Importantly, factors associated with LN characteristics including the maximum diameter and number of metastatic LNs were significantly associated with ENE. Conclusion: In this study, several factors affecting cervical LN metastasis and ENE in oral cancer patients were identified. The ENE seems to be influenced by the status of the metastatic LNs, such as the number of metastatic LNs, rather than the characteristics of the primary tumor itself.

Background/Objectives: Shoulder function is an important aspect of health related quality of life (QOL). Neck dissection impairment index (NDII) is a simple shoulder-specific questionnaire. This study aimed to evaluate the association between QOL and NDII in patients who underwent neck dissection to validate the Korean version of NDII. Materials & Methods: This study enrolled 74 patients with head and neck cancer who underwent neck dissection from December 2013 to April 2014. Patients completed questionnaires on QOL including the European Organization of Research and Treatment of Cancer 30-item Core QOL questionnaire (EORTC QLQ-C30) and NDII which was translated into Korean. Validity was evaluated by calculating the Pearson correlation coefficient between NDII and EORTC QLQ-C30. Results: We compared preoperative, postoperative within a week, 1st and 3rd months NDII scores. The total NDII scores were 14.7, 47.4, 33.7 and 34.3 each. Clinical variables including gender, site of primary tumor, performing revision neck dissection, radiotherapy and flap reconstruction were not significantly associated with NDII. However NDII mean score of patients who underwent unilateral neck dissection over 3 levels is most increased after operation. During all periods NDII scores were significantly associated with functioning score. Although other scores are lower correlation than function scores, global health status scores and symptom scores are also correlation with NDII. Conclusion: NDII was valid instrument and can be used not only in the clinical practice to assess shoulder dysfunction but also in the simple instrument to evaluate global QOL in Korea patients with having neck dissection.

Background/Objectives: Extracapsular dissection has the advantage of reducing complications by minimizing tissue loss of the parotid without intentionally exposing the facial nerve in patients with benign parotid tumor. However, there has been controversy over the surgical results. Thus, the surgical outcomes of extracapsular dissection for benign parotid tumor was compared to those of superficial parotidectomy. Materials & Methods: A retrospective chart review was conducted with 132 patients who received surgery for benign parotid tumor in our center from January 2014 to December 2018 retrospectively. Results: A total of 132 people were enrolled, with 62 people receiving extracapsular dissection, 38 people receiving partial superficial parotidectomy and 32 people receiving superficial parotidectomy. No significant difference was found between the three groups regarding complications such as facial nerve palsy, Frey's syndrome, or first bite syndrome. Operation time and hospital stay was significantly short in extracapsular dissection group. Conclusion: For well-selected cases, extracapsular dissection can be considered as an option for surgery of benign parotid tumor.

Tumor of follicular infundibulum (TFI) is a rare benign cutaneous appendage tumor that does not have characteristic clinical features. It is mainly present in the head, neck, and trunk as a solitary lesion. In particular, TFI typically manifests as a plate-like proliferation with multiple thin epidermal connections comprise of monomorphic cells. TFI do not represent cutaneous characteristics, but have clinical significance because TFI is associated with basal cell carcinoma and Cowden's syndrome. We report a case of TFI in parietal scalp with a review of literatures.

Epithelial-myoepithelial carcinoma is rare, low-grade malignant neoplasm that compromises approximately 1% of all salivary gland neoplasms. We reported a 68-year-old woman with epithelial-myoepithelial carcinoma in the parotid gland. We analyzed demographic and clinicopathological characteristics of salivary gland epithelial-myoepithelial carcinoma which has been reported in 33 cases in Korea from 1992 to 2017, and compared this result to overseas retrospective cohort studies. There was no significance in terms of mean age at diagnosis, the predominance of females, low frequency in regional lymph nodes, and distant metastasis between the two groups. However, T classification and AJCC stage at diagnosis in domestic cases are more advanced than those of overseas cases. Although the recurrence rate in domestic cases has been reported lower than that of overseas, further study may be needed considering that the follow-up period after treatment is short in domestic cases.

Langerhans cell histiocytosis (LCH) is commonly characterized by abnormal function and differentiation or proliferation of monocytes. In LCH, granulomatous lesions, including langerine-positive histocytes and inflammatory infiltrates, can occur to all tissues, particularly well in the bones, skin, lungs, and pituitary gland. In case of external auditory canal LCH, conductive hearing loss may occur, and the most common symptom is otorrhea. Here we present a case that 49-year-old male with external auditory canal mass. Since no invasive findings were seen in radiologic study, endoscopic transcanal excision was performed and LCH was proven by pathologic report. We present this case of external auditory canal LCH with the review of literature.

Liposarcoma is a very rare malignant tumor affecting the head and neck area. Since it is an invasive and life-threatening disease, active treatments is necessary. However, differential it from lipoma, its corresponding benign counterpart, may be difficult. Herein, we report a rare case of posterior neck myxoid liposarcoma in a 72-year-old man who was initially misdiagnosed with lipoma, including a literature review of differential diagnosis between lipoma and liposarcoma.

Plexiform neurofibromas (PNFs) represent an uncommon variant (30%) of neurofibromatosis type 1 (NF-1), in which neurofibromas arise from multiple nerves as bulging and deforming masses involving connective tissue and skin folds. We report the case of a 17-year-old man with known NF-1 presenting with bilateral occipital neuralgia that began in his late adolescence. His chief complaint was radiating pain in the occiput induced by protective helmet wear when riding alpine skiing. Craniofacial magnetic resonance imaging (MRI) confirmed the presence of fusiform masses arising from the bilateral greater occipital nerves. Histopathological examination of the biopsy samples showed PNFs. After surgical treatment, the patient's symptoms completely improved. Unlike cutaneous neurofibromas, PNFs have different clinical characteristics and have the risk of malignant mutations. Correct diagnosis and adequate surgical treatment are necessary for PNFs.

Lymphoepithelial carcinoma is an extremely rare malignant tumor, especially those localized at the head and neck region. The histological prototype of lymphoepithelial carcinoma is undifferentiated nasopharyngeal carcinoma. Herein, we report a case of a tumor localized in the left submandibular gland in a 20-year-old male. The tumor mass was surgically excised with the submandibular gland, and the specimen was pathologically confirmed to be lymphoepithelial carcinoma.

Solitary fibrous tumor (SFT) is rare mesenchymal tumor usually arising from pleura. SFT can be found at all anatomic site in our body but incidence of SFT is much lower in head and neck region especially at lower neck area. We found a case of SFT that presented as a lower neck mass in a 41-year old woman. Ultrasonography showed a 3×1cm sized hypoechoic mass in the intermuscular fat plane of left lower neck, and computed tomography showed a well circumscribed, low-density mass with contrast enhancement. Fine needle aspiration showed no malignant cells with abundant red blood cells, but it was not possible to completely rule out malignant tumors or nodules clinically. Surgery was performed to make a definitive diagnosis and histopathology showed tightly packed, round to fusiform cells with staghorn shaped vessels at microscopic examination. The tumor cell were positive for CD34 but negative for CD31 and S-100 protein.

Primary squamous cell carcinoma of thyroid is a very rare malignant tumor with poor prognosis. It is usually diagnosed as an advanced disease infiltrating adjacent organs, and characterized by aggressive clinical course with an average postoperative survival time of less than 1 year. Recently, we had a 79- year-old woman with a painful neck mass who was diagnosed as primary squamous cell carcinoma of thyroid gland. She underwent total thyroidectomy and selective neck dissection(level III, VI) with no further postoperative managements such as radiation therapy or chemotherapy; she died of poor general condition and pneumonia resulting from rapid progression of the lesion on the 38^th day after surgery. We report this case with a review of relevant literatures.

Pilomatricoma(or calcifying epithelioma) is a not common benign solitary tumor originated from outer root sheath cell of hair follicle or hair follicle of sebaceous glands. The tumor usually presents as an asymptomatic, hard, superficial located, and skin colored to reddish blue cutaneous mass. Most of the tumors are less than 10mm in diameter and adherent to the skin. Recently, 48-year-old man presented with cheek mass. The tumor was 2.6cm sized and located at the subcutaneous layer of cheek on CT scan. The tumor was clearly removed via transoral approach with buccal incision leaving no wound on face. The mass was confirmed as pilomatricoma on pathologic examination. Herein, we report our experience with literature review.

Spontaneous cervical hematomas could lead to life-threatening complications, and aneurysms, retopharyngeal abscesses, parathyroid adenomas, laryngeal cysts, and neurogenic tumors should be distinguished as possible underlying causes. Symptoms accompanying spontaneous cervical hematoma include cervical swelling, ecchymosis, dysphagia, dyspnea and hoarseness. We recently experienced a case of spontaneous cervical hematoma in a 52-year-old woman, who initially presented with cervical swelling after severe coughing two days ago. Resultingly parathyroid adenoma was finally confirmed after mass excision. Therefore, we present this unique case with a review of the literature.

Follicular thyroid carcinoma (FTC) is the second most common thyroid cancer, following papillary carcinoma. Metastasis to the orbital rim from FTC is very rare. We recently experienced a case of FTC with metastasis to the orbital rim in a 74-year-old woman, who initially presented with a huge thyroid mass and an asymptomatic solitary orbital rim lesion. The solitary orbital rim lesion was suspected to be a separate disease entity such as lymphoma from the preoperative imaging, but bone metastasis from FTC was finally confirmed after orbital rim resection and total thyroidectomy. During follow-up, the patient presented multiple bone metastasis, so the solitary orbital rim lesion was considered a clinical sign of systemic metastasis from FTC. Therefore, we present this unique case with a review of the literature.