CYSTIC SQUAMOUS CELL CARCINOMAS OF THE JAWS: TWELVE CASES HIGHLIGHTING HISTOPATHOLOGIC PITFALLS

Background and Objective Cystic squamous cell carcinomas (SCC) of the jaws, including carcinoma cuniculatum (CCu), are rare, slow-growing, and relentlessly invasive. The aim of this study is to document 12 cases. Methods Review of patient hospital notes, histopathologic reports, and original histologic sections. Results Six patients were female and 6 were male (mean age = 74.0 years; range, 50-94). Six tumors affected the mandible and 6 affected the maxillary alveolus with or without extension into the hard palate. Clinical presentation varied, ranging from relatively innocuous-looking ulceration to a grossly ulcerated mass, with radiological evidence of bony destruction in all cases. One patient had multiple dysplastic lesions and was retrospectively diagnosed with proliferative verrucous leukoplakia. For 2 others the tumor was a second primary oral SCC. Histologically, 4 of the 12 tumors were designated as CCu on the basis of deeply endophytic, anastomosing channels of cystic stratified squamous epithelium and keratin microabscesses. The other 8 were also cystic but more heterogeneous morphologically, and though a diagnosis of CCu had been considered in 5 of the 8 cases the final diagnosis was well-differentiated SCC. All patients underwent primary resection with neck dissection and were staged as T4a N0 M0. None developed any notable postoperative complications, but 4 patients died between 6 and 57 months after surgery. In 4 patients diagnosis was delayed as a result of superficial biopsies and/or confusing histopathology. Conclusions Cystic SCC of the jaws can be difficult to diagnose histologically. Clinico-radiological correlation and long-term follow-up are essential.