Squamous cell carcinoma in situ developing in dermoid cyst of the ovary. Report of a case with laminin immunohistochemical staining demonstrating basement membrane integrity.

Among malignancies arising in dermoid cyst of the ovary, squamous cell carcinoma in situ is very unusual and set a problem of diagnosis and prognosis. In fact this diagnosis is very difficult and here we report the case of a 30-year-old woman with a squamous cell carcinoma in a dermoid cyst of the right ovary for which laminin immunohistochemical staining allowed us to prove beyond any doubt the in situ character. This demonstration is of great importance because the prognosis of a squamous cell carcinoma in dermoid cyst depends on the degree of penetration of the tumor; so in this young patient a conservative surgery could be carried out. Four years later the very good evolution confirms the accuracy of the diagnosis of squamous cell carcinoma in situ in dermoid cyst and emphasizes the benefit of laminin labelling in order to rule out the possibility of invasive carcinoma.