Korean J Pediatr 2012;55(6):215-218 • http://dx.doi.org/10.3345/kjp.2012.55.6.215 217 Fig. 3. Histological image compatible with extravasation-type mucocele. The cystic wall does not contain epithelial lining and is bordered by granulation tissue and inflammatory cells. There are mucinous deposits in the cyst lumen (H&E, ×100). The cyst was totally excised with the submandibular and sublingual glands via the external cervical approach (Fig. 2). Histopathologic examination showed a mucocele ruptured with extravasation into the adjacent tissue (Fig. 3). There was no complication in the postoperative period. There was no recurrence during the 2-year follow-up period. Discussion Mucocele is a painless, slow-growing, and fluctuant swelling that is a mucus extravasation or retention of mucous material arising from the salivary gland6). The vast majorities of salivary gland cysts are of minor gland origin, comprise 6% of all parotid lesions, and are non-neoplastic and localized lesions of the duct system7). Mucocele occupies 70% of the salivary cysts and they usually arise from minor salivary glands. It is a rare occurrence in the major salivary glands (parotid, sublingual and submandibular). Extravasation cyst is found in children and young adults, while retention cyst is found in the elderly8). Mucocele originating in the submandibular gland is extremely rare. Our case was a very rare presentation as sequential masses in both submandibular regions of a 16-month-old child. Mucocle has a slight female prevalence of about 1.3:19). Our case was also female. A mucocele is an acquired cyst of traumatic or non-traumatic origin and develops from the salivary glands10). There are two types of mucoceles-one in which mucus has extravasated into the tissues (extravasation cyst) and one which is lined with epithelium (retention cyst). Partial obstruction of the distal end of the duct will produce dilatation resulting in an epithelial-lined retention cyst, whereas disruption of the duct with mucus extravasation will produce a pseudocyst without a distint lining11,12). Our case was compatible with extravasation cyst. Ranula is a clinical term used to designate a mucocele that occurs in the floor of the mouth. Plunging ranula and cervical ranula extend below the mylohyoid muscle, beyond the sublingual space, and involve the submandibular space and adjacent structures13). Clinically, it is difficult to distinguish plunging ranulas from mucoceles origina- ting from the submandibular gland. Elevation of the floor of the mouth on the affected side and a bluish discoloration hint at the origin of these lesions; however, these are not always present. A CT scan with contrast and MRI can be helpful in demonstrating the origin of these lesions. Usually, when the lesion arises from the sublingual gland, a so-called "tail" sign is diagnostic14). This is a radiolucent and duct-like extension between the lesion and the sublingual gland, and it is usually located at the posterior margin of the mylohyoid muscle or in a dehiscence in the muscle. In this case, CT and MRI did not show the "tail" sign. The diagnosis of mucocele is based principally on the clinical examination and radiographic findings. Fine needle aspiration cytology should be performed and demonstrates mucus with inflammatory cells and also can exclude other neoplastic lesions, such as malignant lymphoma. Chemical analysis of mucus contents reveals high amylase and protein contents15). CT scanning and MRI can provide accurate localization of the lesion and assist in determining its origin. Sialography provides minimal information16). After excision of the mass, histopathologic diagnosis prove confirmatory, demonstrating a cyst-like structure that is bordered by granulation tissue with no epithelial lining detected; the present case produced compatible findings. Treatment of submandibular mucocele involves marsupialization, incision, drainage, cystectomy, excision of the sublingual gland and/ or the submandibular gland with mass, irradiation, and injection of sclerosing agents17). Several investigators have suggested that to prevent recurrence, treatment of submandibular mucocele should be managed by removing the lesion with both the submandibular and the sublingual glands. The surgical modes are accomplished through transoral and transcervical approaches or through combined transoral and transcervical approaches18). The presented case, with left submandibular gland mucocele, was treated by removing the lesion.