๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Branchial Cleft Sinuses and Fistulae
Synonym:๏ก Lateral cervical sinuses and fistulae
Branchial cleft sinuses most often represent remnants of the second branchial (pharyngeal) cleft. They are usually detected at birth or during the first few years of life, unlike the more common branchial cleft cysts that lack a primary cutaneous opening and typically present in older children and adults (see Ch. 110). The ostium of a second branchial cleft sinus is located on the lateral lower third of the neck along the anterior border of the sternocleidomastoid muscle, and there is frequently a history of mucus discharge; the associated tract extends superiorly in the subcutis and may be palpable. The less common first branchial cleft sinus can manifest with a cutaneous opening located higher on the neck or in the periauricular region. Approximately 70% of branchial cleft sinuses are located on the right and 5%โ10% are bilateral. There may be a history of recurrent infection, and a skin tag, sometimes with a cartilaginous component, can mark the ostium. Most branchial sinus tracts end blindly, but occasionally there is a fistulous connection with the tonsillar fossa of the pharynx or the external auditory canal. Rarely, thyroid or squamous cell carcinoma develops within branchial cleft remnants.
Although usually an isolated malformation, branchial cleft sinuses and fistulae are also features of several multiple congenital anomaly syndromes. These include the branchio-otic and branchio-oto-renal syndromes, autosomal dominant disorders that also feature ear pits, hearing loss, and, in the latter, renal anomalies. These syndromes can be caused by mutations in the EYA1 (both conditions), SIX1 (branchiootic), and SIX5 (branchio-oto-renal) genes, which encode transcription factors that interact within a complex. Atrophic, eroded, or โhemangiomatousโ skin overlying branchial cleft sinuses on the neck or in the periauricular area is a distinctive feature of the branchio-oculo-facial syndrome that is due to mutations in the gene encoding transcription factor AP2-ฮฑ. Additional manifestations of this disorder include cleft lip/palate, imperforate nasolacrimal ducts, eye and ear anomalies, and early graying of the hair.
Histologically, a branchial sinus may be lined by stratified squamous or pseudostratified ciliated columnar epithelium. In order to prevent infectious complications, complete surgical excision of branchial sinuses and fistulae is indicated. Imaging may be helpful in delineating the course and extent of the lesion, although recommendations vary among otolaryngologists. Preoperative options include CT fistulography and MRI; in addition, intraoperative contrast fistulography and/ or injection of methylene blue dye can be considered.