A Rare Case of a Primary Leiomyoma of the Clivus in an Immunocompetent Patient and a Review of the Literature Regarding Clival Lesions.

Leiomyomas are common lesions that are usually located in the genitourinary and gastrointestinal tracts. Primary leiomyomas at the skull base are uncommon. They are composed of well-differentiated smooth muscle cells without cellular atypia. The diagnosis of a leiomyoma has to be confirmed by immunohistochemistry. The tumor tissue is immunoreactive for SMA, S100 and cytokeratin. Leiomyomas mainly occur in immunocompromised patients. Most tumor tissues are positive for EBV. The presented case is that of a 56-year-old immunocompetent woman with a tumor on the clivus. The radiological images suggested chordoma or fibrous dysplasia. Transnasal transsphenoidal surgery was performed. The tumor tissue consisted of well-differentiated smooth muscle cells with elongated nuclei. Immunohistochemistry revealed a positive reaction for desmin, SMA and h-Caldesmon and a negative reaction for S100, beta-catenin, PGR and Ki67. The leiomyoma diagnosis was subsequently established. To the best of our knowledge, the case of a primary leiomyoma on the clivus of an immunocompetent patient is the first to be described. We also extensively reviewed the literature on the immunohistopathological and radiological differential diagnosis of clival lesions.