Orbital cavitary rhabdomyosarcoma: a diagnostic dilemma.

The authors present a rare form of orbital cavitary rhabdomyosarcoma in which lymphangioma was mistakenly diagnosed on the basis of echography and MRI. Rhabdomyosarcoma can usually be differentiated from lymphangioma by echographic and MR imaging, because cavitation is very rare in orbital rhabdomyosarcoma, but rhabdomyosarcoma should be suspected whenever the clinical presentation of a rapidly progressive unilateral exophthalmos is observed in a child.