齋藤 大輔

Daisuke SAITO

岩手医科大学耳鼻咽喉科頭頸部外科

Otorhinolaryngology-Head and Neck Surgery, Iwate Medical University

キーワード : head and neck ultrasonography, cervical tumor, cervical lymph node metastases, head and neck squamous cell carcinoma, diagnostic criteria

体表や頸部の腫瘤を主訴に外来を受診する患者は多く，その診断において，非侵襲的でリアルタイムに情報を得られる超音波検査が果たす役割は大きい．しかしながら，頸部は血管・神経・筋肉・腺組織など様々な組織が複雑に存在するため，正常解剖を理解したうえで超音波検査を行うことが重要となる．解剖を理解するうえでも，頸部全体を系統的に観察するスクリーニング検査を習熟する必要がある．甲状腺，頸動脈・静脈，顎下腺，オトガイ部，耳下腺，外側頸部と基本画像を数ヵ所決め，その部位を観察し記録しておくことが推奨される．頸部を慎重に観察すると，リンパ節が辺縁明瞭の扁平楕円形低エコー腫瘤として多数描出される．正常リンパ節では，内部にfatty hilumと呼ばれる小さな高エコー域を認める.カラードプラでは，fatty hilumに沿った血流を認める．頭頸部癌の転移リンパ節ではこの正常構造が破壊され腫大するため，超音波にて正常との鑑別が可能である．頸部に出現する他の腫瘍としては，甲状腺・唾液腺腫瘍や神経原性腫瘍，脂肪腫，嚢胞性腫瘤，血管腫などがある．それぞれに特徴的な超音波像があるため，形状や発症部位，内部血流などを詳しく観察して診断する必要がある．体表・頸部では視診・触診も可能なのでこれも診断の一助となる．

Many patients visit outpatient clinics suffering from tumors of the body surface and the neck. Ultrasonography is very useful because it is noninvasive and can provide information in real time. There is a complicated array of various tissues in the neck including blood vessels, nerves, muscles, salivary glands, and so. It is important for us to understand the anatomy when performing ultrasonography. It is necessary for us to master the screening examination to scan the whole neck systematically to understand the anatomy. We select several parts of basic images in the neck such as the thyroid gland, common carotid artery, internal jugular vein, submandibular gland, mental region, parotid gland, and outside neck. Scanning results of these parts should be recorded. Many lymph nodes are depicted as flat, oval, low echoic masses of the clear border when we carefully scan the whole neck using ultrasonography. In the central part of the normal lymph node, we recognize a small, high echo part called the fatty hilum. We detect the bloodstream along the fatty hilum on color Doppler imaging. This normal lymph node structure is destroyed in metastatic lymph nodes of head and neck cancer as they swell. Therefore, ultrasonography allows the differential diagnosis of normal lymph nodes and metastatic lymph nodes. Other tumors often appearing in the neck include thyroid gland tumors, salivary gland tumors, neurogenic tumors, lipomas, cystic tumors, and hemangiomas. Since there are characteristic ultrasound images of each tumor type, it is necessary to discern the shape, onset site, and internal bloodstream in detail for accurate diagnosis. Inspection and palpation help the diagnosis of body surface and head and neck tumors.