White sponge nevus (WSN) is a rare autosomal dominant disorder characterised by rough thickening, fissure formation, and a whitish colour change in the oral mucosa. This disorder predominantly affects the nonkeratinized stratified squamous epithelium of the mucosa. We experienced a familial case of WSN (i.e., a mother and her two daughters) and performed keratin gene analysis and immunohistochemical staining. The results of a mutation analysis revealed the presence of a heterozygous missense mutation 344T to G in KRT13, predicting an amino acid change leucine (L) to arginine (R), in the 1A domain of the KRT13 polypeptide. Immunohistochemically, the loss of keratin 4 expression was found.

There are many case reports about cysts within the bones of the jaws associated with impacted third molars. When osmotic pressure is introduced into a cyst, the cyst expands and displaces the third molar. If continuity of cyst wall is lost, cystic expansion cannot occur, and the cyst cannot displace the third molar. This study analyzed four cases of pathologic migration of the third molar in ruptured cystic lesions that had formed bone tunnels and intraoral fistulas to identify the causes and factors contributing to this migration. Authors hypothesized that closure of fistulas repeated generation of pressure, it may temporarily increase the osmotic pressure within a cyst that has lost its continuity, causing displacement of the third molar. A cyst that has lost its continuity due to fistula formation within the oral cavity can cause ectopic displacement of the adjacent impacted teeth.

Epidermoid cyst of the oral and maxillofacial region is a soft tissue cyst lined with keratinized stratified squamous epithelium and most commonly arises in the superficial area of the mouth floor. Uncommonly, the epidermoid cyst may arise deeply in the submandibular region and should be differentially diagnosed with cystic salivary gland tumors, developmental cysts and other cystic lesions. We report a rare case of an epidermoid cyst near the submandibular gland, clinically and radiographically mistaken as a salivary gland tumor.