LAUSR

A 39-year-old male reported to us, with a chief complaint of a swelling at the lower right back region of jaw since 2 months associated with occasional dull-aching pain. The swelling extended antero-posteriorly from the corner of the mouth to the angle of the mandible and superior-inferiorly from the corner of the mouth till the inferior border of the mandible and roughly measured 4 9 5 cm. Obliteration of buccal vestibule was seen extending from the second premolar till the retromolar trigone on the same side. Mouth opening was as less as 14 mm inter-incisally (Fig. 1).These clinical features were suggestive of a probable benign lesion. The orthopantomogram (OPG) showed a multilocular radiolucency with ill-defined margins suggestive of a probable primary intraosseous carcinoma. The FNAC revealed a greenish yellow viscous fluid suggestive of an infected cyst after which extraction of the first molar was done and a part of the underlying tissue was curetted and sent for histopathological examination. Biopsy report revealed epithelium of odontogenic keratocyst showing mild to moderate dysplastic features along with connective tissue showing islands of malignant epithelial cells (Fig. 2).These overall features were suggestive of squamous cell carcinoma arising from cystic lining or collision tumor. A USG neck and CECT (Fig. 3) revealed that level I and II cervical lymph nodes were involved on the right side. After all routine preoperative investigations, preanesthetic fitness was obtained and the patient was taken up for surgery. Patient was taken under general anesthesia and a composite resection, modified radical neck dissection and reconstruction with pectoralis major myocutaneous (PMMC) flap were done. The excisional biopsy report concluded that out of 39 lymph nodes that were dissected, 31 had metastatic deposits along with vascular invasion. The correlation of clinical and histopathological findings suggested that the lesion could be oral carcinoma cuniculatum arising from odontogenic keratocyst owing to the Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12663-020-01461-5) contains supplementary material, which is available to authorized users.