Epidermoid cysts are benign pathologies that can occur anywhere in the body, predominantly seen in areas where embryonic elements fuse together1. Most cases have been reported in the ovaries and the testicles (80%), with head and neck accounting for 7% 12. Dermoid and epidermoid cysts in the mouth are uncommon and comprise less than 0.01% of all the oral cysts 234. Majority of them occur in sublingual region, but there are rare case reports of occurrence in other sites

The tongue is a complex of muscle groups with a fibrous scaffold consisting of the hyoglossal membrane and midline lingual septum.

The root of the tongue is an important sub region of the oral cavity, associated with very specific differential diagnoses. It is relatively resistant to primary neoplastic and infectious processes due to its high percentage of skeletal muscle and lack of significant lymphatic tissue .

The majority of lesions found in the root of the tongue are congenital and benign, representing ectopic tissues of thyroidal, epidermal, dermal, foregut, venous, and lymphatic origin.

The most common midline mass at the base of the tongue is a lingual thyroid which should be confirmed or excluded by radionuclide scanning.

Lingual cysts are extremely rare in the neonate and young infant Epidermoid and dermoid cysts are rare, benign lesions found throughout the body, with 7% occurring in the head and neck area, 1.6% of which occurs in the oral cavity. Of all the oral cysts dermoid cysts account for only 0.01% 234 Roser was the first to designate dermoid cysts in the floor of the mouth as epidermoid tumors 5 Even though the expression "dermoid cyst" characterizes a distinct entity, the word "dermoid" has been used to designate true dermoid cysts, epidermoid cysts, and teratoid cysts 236 Based on the histopathological picture Meyer divided the floor of the mouth cysts into following types: 124

 Epidermoid cysts - where in the cystic cavity is lined with epithelium without skin appendages ( like our case)

. Dermoid cysts - here the epithelial lined cystic cavity encloses skin appendages such as hair, hair follicles, sebaceous, and sweat glands.

 Teratoid cysts - in this entity, the cystic cavity in addition to skin appendages also encloses mesodermal derivatives such as bone, muscle, gastrointestinal and respiratory tissue.

All these three cysts owing to their squamous epithelium lining may enclose cheesy keratinaceous material within their lumen. Hence the fundamental difference between the dermoid and the epidermoid is the presence of skin appendages within the wall of the former and the lack of the same in the latter 36.

Epidermoid cysts may be categorized as congenital or acquired based on their origin although there is no disparity between the two either clinically or histologically 247

In medical literature, a variety of terms have been used for tongue base cysts, such as epiglottic cyst, lingual cyst, vallecular cyst,or laryngeal cyst^1–8.Two major hypotheses to explain the pathogenesis are that this cyst is a consequence of either ductal obstruction of mucus glands or an embryological malformation 2. Histologically, the cyst contains respiratory epithelium with mucous glands, with an external lining of squamous epithelium 234. Most affected infants have symptoms during the first week of life 5. Clinical manifestations consist of various degrees of upper airway obstruction such as inspiratory stridor, chest retraction, apnea, cyanosis, and feeding difficulty. Stridor is the most common symptom 12345678. About 60% of children with stridor have laryngeal obstruction such as laryngomalacia, vocal cord paralysis, subglottic stenosis, hemangioma, or laryngeal cysts; 25% have lesions in the upper airway, including choanal atresia, macroglossia follow-up is necessary in case of recurrence 1. Primary diagnostic approach to laryngeal or vallecular cysts should be a flexible nasopharyngeal laryngoscopy or bronchoscopy. CT and MR imaging often help narrow the differential diagnosis such as lingual thyroid, proximal cystic dilatation of the thyroglossal duct, lymphangioma or hemangioma, dermoid cyst, lipoma, fibroma, or carcinoma 6. Although surgical removal may be the treatment of choice, other modalities such as endoscopic marsupialization, excision, and deroofing of the cyst have been recently developed. Marsupialization under general anesthesia is a safe and definitive procedure, especially when performed by CO2 laser. Sometimes, preincubation aspiration becomes necessary before the insertion of the endotracheal tube. Simple aspiration of the cyst is not advised because of its high recurrence rate 123456. Spontaneous disappearance of a tongue base cyst after oropharyngeal suctioning has not been previously reported 12345678. In conclusion, tongue base cysts should be considered in differential diagnosis in new born with stridor, respiratory difficulties, or swallowing problems. An endoscopic laryngobronchoscopy has to be performed d before making the diagnosis of laryngomalacia. Definitive therapy requires large marsupialization under general anesthesia].

Traumatic or iatrogenic inclusion of epithelial cells or the blockage of a sebaceous gland duct have been postulated as the pathogenesis of acquired cyst 47. However, some authors have also stated that midline cysts may represent a diverse form of thyroglossal duct cyst 467.

Although floor of the mouth in the midline is most favored site, occasional occurrence involving the buccal mucosa, tongue, lips, uvula, temporomandibular joint dermal graft, intradiploic, intracranial, and intraosseous location within the mandible and maxilla also have been cited in literature 489. These lesions show variation in size and weight from few millimeters to centimeters and a gram to several hundred grams respectively 35. Symptoms of dysphagia, dyspnea and dysphonia may occur due to upward displacement of tongue by these sublingual swellings 45. Furthermore growth in an inferior direction may give rise to appearance of characteristic "double chin" 148. These well encapsulated lesions typically feel "dough like" on palpation, although they may be fluctuant and cyst like based on consistency of the luminal contents, that may range from a cheesy, sebaceous to liquefied substance 156.

Fine needle aspiration cytology, ultrasound, CT and MR imaging provide essential information on the cyst location that allows optimal preoperative planning. Ultrasonographic findings comprise solid and cystic structures within a heterogeneous mass 3. On CT scans, the dermoid appear as moderately thin walled, unilocular masses filled with a homogeneous, hypoattenuating fluid substance with numerous hypo attenuating fat nodules giving the pathognomonic "sack-of-marbles" appearance 3. On MR imaging dermoid cysts give variable signal intensity on T1-weighted images and are usually hyper intense on T2-weighted images 39. Fine needle aspiration cytology has been advocated as an essential investigation. Although not equivalent to CT and MRI, it is safe, economical and dependable technique and is therefore useful for analysis of sublingual lesions 16.

Treatment comprises total surgical excision 1246. Caution should be taken not to rupture the cyst, as cystic contents may act as irritants to fibro vascular tissues, causing postoperative inflammation 3. Recurrences are unusual after absolute surgical excision 13. Reports of malignant transformation of sublingual dermoid and epidermoid to squamous carcinoma and basal cell carcinoma are present 12. A 5% rate of malignant transformation of the teratoid variety of oral dermoid cysts has also been quoted in literature 35.

we present a very rare case of lingual cyst located at the posterior third of the tongue. Lingual cyst has a verities of presentations ranging from asymptomatic child down to severe obstruction as in our patient with florid manifestation such as frequent vomiting, aspiration, dysphagia, failure to thrive, repeated aspiration, pneumonia ,frequent wheeze and respiratory distress. High index of suspicion together with watching a baby during his complete process of feeding is very beneficial to reach a final diagnosis.