Congenital duplication of submandibular ducts.

Bilateral duplication of submandibular ducts ending in a ranula was revealed by sialography and confirmed by T2weighted SSh sequence using magnetic resonance cholangiopancreatography (MRCP) parameters. A literature search revealed 2 previous reports of submandibular duct duplication, but a ranula associated with submandibular duct duplication has not been previously reported. A review of congenital anomalies of the submandibular ducts is presented and the value of non-invasive MR imaging is discussed. A 19-year-old woman is presented with one centimeter, translucent, fluctuant, sublingual cystic swelling. The swelling appeared to increase in size following a meal. There was no previous history to note; and a full blood count and blood biochemistry appeared normal. No salivary duct calculus was identified on conventional radiographs. At sialography, bilateral submandibular duct duplication showed the ducts terminating in a ranula. The anatomy was elegantly and non-invasively depicted by T2-weighted SSh rad, the same parameters used for MRCP, TR8000 and TE1100 (Figure 1). Congenital anomalies of the submandibular ducts are rare. Pownell et al1 reported 5 newborns that presented with cystic lesions of the floor of mouth. Four of these patients proved to have congenitally imperforate submandibular salivary gland ducts, and the other newborn proved to have a duplication anomaly of the submandibular gland duct and gland. The diagnosis of congenital anomalies of the submandibular gland and duct can be made on physical examination. Magnetic resonance imaging can be helpful in differentiating congenital imperforate submandibular duct and duplication anomalies of the ductal system. A failure in diagnosis and treatment may result in ranula formation or sialoadenitis requiring more extensive therapy. Amin and Bailey2 presented 2 infants with unilateral cystic swellings in the floor of the mouth as a result of imperforate submandibular ducts. This is thought to result from a congenital failure of canalization of the terminal end of the duct. Both cases responded to simple incision and decompression of the fluid-filled duct. Early treatment is important to avoid feeding difficulties and to prevent later complications such as ranula or sialadenitis. Other anomalies of the submandibular salivary gland and duct include bilateral Wharton duct, bilateral submandibular duct atresia, bilateral congenital absence of the duct orifice, and congenital dilatation of the submandibular ducts and imperforate salivary ducts with a result of sublingual cystic swelling. Differential diagnosis of cyst-like swelling of the mouth floor. The differential diagnosis of cyst-like swelling in the floor of the mouth includes sialolithiasis, mucous retention phenomenon (mucocele, ranula), dermoid, epidermal inclusion cyst, thyroglossal duct cyst, branchial cleft cyst, hemangioma, lymphangioma, cystic hygroma, lipoma, and occasionally pleomorphic adenoma. Ranula is a raised mucocele on the oral floor. When the mucocele extends and passes the sublingual space and invades the Clinical Notes