Primary intraosseous squamous cell carcinoma arising in odontogenic cysts: a series of three cases with immunohistochemical analysis

Abstract

<h3>Introduction</h3> Carcinomatous transformation in odontogenic cysts is rare, with few cases described in the literature. Squamous cell carcinoma (SCC) is the most common form of malignant transformation in odontogenic cysts. Radicular and dentigerous cysts are the most common odontogenic cysts to undergo malignant transformation. We present three cases of primary intraosseous carcinoma (PIOC) arising in odontogenic cysts. <h3>Method and Materials</h3> Following IRB approval, cases were identified from the University of Florida Biopsy Service archives (1994-2020). The clinical and demographic data was reviewed, along with radiographs and original slides. An immunohistochemistry (IHC) panel including CK19, p53, and Ki-67 was performed on all cases. <h3>Results</h3> The first case occurred in a 67-year-old male with a radiolucency around impacted #17. Microscopically, a verrucous carcinoma was diagnosed arising within a developmental odontogenic cyst, most likely an orthokeratinized odontogenic cyst. The second case involved a 59-year-old male with a lesion adjacent to tooth #15. Histologic examination revealed a well differentiated SCC arising from an odontogenic keratocyst (OKC). The final case involved a 13-year-old male with a radiolucency near teeth #6-7. A well differentiated SCC was diagnosed arising from an OKC. Further investigation to assess for Nevoid Basal Cell Carcinoma Syndrome was recommended for this case, but the outcome was unavailable. IHC analysis revealed P53 positivity for all cases. Ki67 showed 80-90% positivity in the basal layer of the odontogenic epithelium for cases 1 and 3, and 50% positivity for case two. Ck19 was only focal positivity in all cases. <h3>Conclusion</h3> We present three cases of squamous cell carcinoma arising within odontogenic cysts. P53 and Ki-67 positivity aid in confirmation of the aggressive nature of each tumor. CK19 staining was weak, despite the obvious odontogenic nature of the epithelium in all cases. Careful follow-up for odontogenic cysts demonstrating recurrence or progressive growth is imperative.