Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Case Report Med Princ Pract 2009;18:248–252 DOI: 10.1159/000204360 Coexistence of Mucous Retention Cyst and Basal Cell Adenoma Arising from the Lining Epithelium of the Cyst Report of Two Cases D. Antoniades a A. Epivatianos a A. Markopoulos a A. Kolokotronis a T. Zaraboukas b Departments of a Oral Medicine and Oral Pathology and b Histopathology, University of Thessaloniki, Thessaloniki, Greece vimentin and -smooth muscle actin. Based on the results, a diagnosis of coexisting mucous retention cysts and basal cell adenomas arising from the lining epithelium of cysts was made. Conclusion: The coexistence of mucous retention cysts and basal cell adenomas arising from the lining epithe- lium of the cyst is reported. Copyright © 2009 S. Karger AG, Basel Introduction Salivary gland cysts represent about 6–9% of all sali- vary gland diseases [1]. The development of salivary gland tumors in preexisting salivary gland cysts is extremely rare. Research of the literature disclosed only 5 cases [1– 4] , in which no case of a mucous retention cyst with the development of basal cell adenoma has been presented. Furthermore, the formation of a mucous retention cyst secondary to the presence of basal cell adenoma in the lining epithelium of the cyst, to the best of our knowl- edge, has not been reported. We report 2 cases of the coexistence of a mucous reten- tion cyst and basal cell adenoma arising from the lining epithelium of the cyst. Key Words Mucous retention cyst  Basal cell adenoma  Salivary gland tumors  Salivary gland cysts Abstract Objective: To report 2 cases of coexisting mucous retention cyst and basal cell adenoma arising from the lining epithe- lium of the cyst. Clinical Presentation and Intervention: Two cases of painless swellings, well-demarcated, soft to palpation, and located in the submucosa of the upper lip were clinically examined with the provisional diagnosis of mucocele or salivary gland tumor. Histological examination showed the presence of a large unilocular cystic cavity in many parts surrounded by single or bilayered lining epithe- lium composed of flattened to cuboidal cells, and in other parts surrounded by projections of cells arranged in a tra- becular pattern far into the cystic cavity. The trabeculae were composed of basal and low columnar cells that some- times formed small duct-like structures. Immunohistochem- istry showed that the lining epithelium of the cystic cavity and the cells of the projections expressed cytokeratin 7 and high-molecular-weight cytokeratins. The cells of the projec- tions were weakly positive for S-100 protein and negative for Received: December 24, 2007 Revised: June 19, 2008 A. Epivatianos Department of Oral Medicine and Pathology, Dental School University of Thessaloniki GR–54124 Thessaloniki (Greece) Tel. +30 2310 999 521, Fax +30 2310 999 455, E-Mail aepivati@dent.auth.gr © 2009 S. Karger AG, Basel 1011–7571/09/0183–0248$26.00/0 Accessible online at: www.karger.com/mpp