[About a case of rhabdomyosarcoma with an aberrant expression of epithelial markers: a cause of misdiagnosis].

We present the case of an embryonal rhabdomyosarcoma of orbitary location with aberrant expression of epithelial markers in a 51-year-old female. The rhabdomyosarcoma is a rare tumor of soft tissues affecting mainly the child, but also exceptionally adults over 50. When it presents as a small round cells tumor, particularly in the region of head and neck, its differential diagnosis with several other poorly differentiated tumors may be difficult. Several cases of rhabdomyosarcoma with aberrant expression of epithelial markers have been reported in the literature. A large immunohistochemical panel is recommended by recent studies in order to avoid diagnostic errors. It includes large spectrum cytokeratins, desmin, neuroendocrine, melanocytic and lymphoid markers. Our observation confirms the importance of conducting this immunohistochemical panel including desmin in the context of a poorly differentiated tumor of the head and neck region. It should be performed whatever the age of the patient and even if the tumor expresses epithelial markers.