Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2009.1385.1387YazdaniN. Khorsandi-AshtianiM. Rabbani-AnariM. BassamA. KouhiA. 1220091220Keratoacanthoma (KA) is a rapidly growing, low-grade neoplasm of pilo-sebaceous and hair follicle units which most often appears on the sun-exposed skin of the middle aged and older persons with multiple or localized occurrence. This tumor is dome-shaped nodule with a central keratinous plug. The etiology of this tumor is not obvious. Exposure to excessive sunlight is the most frequently noted responsible factor in the etiology of KA. About 80% of the tumors occur on the face. The histological features of the KA are often very similar to those of a cutaneous squamous cell carcinoma; however, the tumor structure usually provides a basis for their difference. There are many unusual cases of keratoacanthoma reported regarding site, size or other specifications. In this study, we excised a mass of nasal vestibule, a site far away sun-exposure. To our knowledge, this is the first case of nasal vestibular keratoacanthoma. For a clinician and a pathologist it is important to consider a benign lesion like Keratoacanthoma (KA) in the differential diagnosis of ulcerated nasal lesions and pay attention to differ it from Squamous Cell Carcinoma (SCC ) which has a different and aggressive management.]]>Chen, Y.K., L.M. Lin, C.C. Lin and C.H. Chen,2003128581582Chow, T.K., E. Chacko, C. Cleary, S. Kennedy and L. Cassidy,200519689690Denkler, K. and W. Kivett,200611725162517Godbolt, A.M., J.J. Sullivan and D. Weedon,200142168171Goodwin, R. and G. Fisher,1980897274Khorsandi-Ashtiani, M.T., N. Yazdani, F. Japaydarfar, F. Sadri and F.M. Akouhi,2009123915918Moriyama, M., T. Watanabe, N. Sakamoto, M. Suzuki and G. Mogi,200027185188Patterson, H.C.,198391263270Schwartz, R.A.,199430119Sean, F., B. Pattee and N. Silvis,2003483538Sheyner, I. and V. Osipov,20065419721973Sullivan, J. and G. Colditz,1979203440