Takafumi Yamada

Bio: Takafumi Yamada is an academic researcher from Meirin College. The author has contributed to research in topics: Neck dissection & Tongue. The author has an hindex of 1, co-authored 2 publications receiving 2 citations.

Pattern of Invasion and Invasive Front Grading Score as Predictive Factors of Late Cervical Lymph Node Metastasis in Surgically Treated Stage I∼II Tongue Carcinomas

Abstract: Cervical nodal metastasis has a major influence on survival in squamous cell carcinoma (SCC) of the tongue. However, predictive factors for metastasis remains inconclusive, especially in stage I-II SCC of tongue. This study analyzed the clinicopathologic factors associated with late nodal metastases in patients with stage I-II SCC of tongue. The clinicopathologic factors of 62 consecutive patients between January 1998 and December 2001 with surgically treated stage I-II SCC of the tongue were reviewed prospectively, and the factors predicting late cervical nodal metastasis were analyzed. All patients were treated with partial glossectomy without elective neck dissection. Fourteen of 62 (22.6%) developed late cervical nodal metastases within median follow-up of 36 months. Thirteen patients (92%) developed late nodal metastases within 13 months. In Cox regression analysis, pattern of invasion at the invasive tumor front and invasive front grading score had predictive values for late nodal metastasis. Patients who are surgically treated for stage I-II SCC of tongue with diffused invasive pattern at invasive tumor front and high invasive grading score should be carefully followed up, and delayed elective neck dissection after partial glossectomy should be carried out in selective patients.

A clinical study of odontogenic keratocyst

Abstract: Odontogenic keratocyst (OKC) is classified as a developmental cyst derived from odontogenic organs such as enamel organs and dental lamina. The main histological feature of OKCs is keratinization in the cyst wall, sometimes including islands of epithelium that may represent daughter cysts in a thin epithelium lining. Clinically, this disease is characterized by a high frequency of recurrence.In this retrospective study, we examined 91 OKCs treated at the Department of Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University Hospital between 1981 and 1995. The ages of the patients ranged from 7 to 69 years (mean age, 30.5), and 50 were male and 41 were female. The most common sites were the molar region and ramus of the mandible. Most of the OKCs in the maxillary region were treated by enucleation and primary closure. Most OKCs in the mandibular region were enucleated, and the wound was left open. Marginal mandibulectomy was performed in two patients with large lesions arising in the mandible. The postoperative course was uneventful in 52 cysts (85%), and recurrence occurred in 9 cysts (15%) among 61 cysts followed-up for more than 2 years. Recurrence occurred near the roots of teeth.In most patients, no symptoms were associated with recurrence. Recurrence occurred in 4 patients more than 10 years after operation. Our findings indicate that long-term follow-up and careful treatment of lesions continguous with the roots of teeth are required in patients with OKCs.

A clinical study on the recurrence of keratocystic odontogenic tumor

Abstract: 角化嚢胞性歯原性腫瘍は，歯原性上皮に由来する単房性もしくは多房性の顎骨内腫瘍で，錯角化を呈する重層扁平上皮により裏装されている。多発性の本腫瘍は母斑基底細胞癌症候群の徴候の一つとして知られている。本腫瘍の臨床的な特徴としては，周囲組織に対して侵襲的な態度を示すことや，再発傾向があることなどがある。今回われわれは，2001年から2010年までの10年間に東京医科歯科大学歯学部附属病院顎口腔外科で加療した角化嚢胞性歯原性腫瘍68例（男性39例，女性29例），90腫瘍について臨床的に検討した。このうち8例（男性3例，女性5例），30腫瘍は母斑基底細胞癌症候群例であった。全90腫瘍のうち24腫瘍で再発を認め，再発率は26.7%であった。開窓・摘出術を行った腫瘍の再発率（16.1%）は，開窓療法を行わず摘出術を行った腫瘍の再発率（34.5%）より低かった。腫瘍に接する歯を根治的に処置した腫瘍の再発率（3.4%）は，保存的に処置した腫瘍の再発率（37.7%）より低かった。再発は，その多くが保存した歯の歯根付近から生じていた。これは，この部位は腫瘍の摘出が困難なため，不完全になってしまうことによると考えられた。腫瘍の摘出から再発までの期間は6か月から5年に分布し，ほとんどが3年以内であった。よって，腫瘍摘出後は最低3年間は定期的に経過観察を行う必要があると考えられた。