September 2019 HSC Section 1 Congenital and Pediatric Problems

Yuhan et al

Fig. 4. Ranula. Coronal ( A ) and sagittal ( B ) contrast-enhanced CT showing a low-density cystic lesion involving the sublingual space.

Nonodontogenic cysts Cysts involving the jaw are often visualized intraorally and are broadly classified as either odontogenic or nonodontogenic depending on the tissue’s embryologic origin. Believed to arise from entrapped epithelium, some nonodontogenic cysts were histor- ically known as “fissural” cysts. These cysts usually resolve spontaneously within the first 3 months of life. 25 Epstein pearls, found in up to 80% of all newborns, are observed along the medial palatal raphe. 25 Bohn nodules are true inclusion cysts that develop from remnants of minor salivary glands. They visually present as white papules and may cluster or appear as an isolated nodule. 31 Often appearing between the second and fourth month after birth, most Bohn nodules disappear within a few weeks to months. 31 Foregut duplication cysts arise from embryologic remnants of the stomach through the second part of the duodenum. 32 Oral involvement is rare, making up 0.3% of all duplication cysts. 33 Children with oral foregut duplication cysts may present with dysphagia or airway obstruction. 34 Although surgical excision remains the mainstay of treatment, any sign of respiratory compromise should be addressed via intubation or, in rare cases, tracheostomy. 32 Congenitally acquired dermoid cysts are benign neoplasms that may contain hair follicles, sebaceous glands, or sweat glands. Approximately 7% of dermoid cysts occur in the head and neck region, with 23% of those located at the floor of the mouth. 35 Submental swellings result in the characteristic double-chin appear- ance. 36 Clinically, these lesions are slow growing and most often asymptomatic. They occur in the midline and may display hypoattenuation and a sack-of- marbles appearance on CT scan ( Fig. 5 ). 5 Successful extraction is associated with a low rate of recurrence due to the presence of a fibrous capsule that enables ease of enucleation. 37 Odontogenic cysts Odontogenic cysts are traditionally subclassified as either inflammatory or develop- mental depending on their underlying pathogenesis. In 1 study, cystic lesions account for 80% of all odontogenic lesions. 38 There are dozens of different types of odonto- genic cysts; however, several are more clinically relevant and should be included in a comprehensive differential diagnosis.

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