Rhabdomyoblastic differentiation in rosai dorfman disease of the orbit in a 12-year-old male.

Extranodal Rosai-Dorfman disease involving the orbit has been reported severally with extensive discourse on management strategies. However, rhabdomyoblastic differentiation coexisting with the disease is yet unreported. We present the clinical and histopathological features of a 12-year-old boy presenting with both. A 12-year-old boy was referred to our Ophthalmic Plastic Surgical Service with a 5-year history of bilateral, progressively enlarging eyelid, orbital masses causing proptosis, and severe cosmetic blemish. He had suffered vision loss to the right eye following trauma 2 years prior to the onset of the disease. Computed tomography of the orbits revealed preseptal and intraorbital components of well-defined multi-lobulated masses in both orbits. No significant nodal involvement was noted. He underwent excision biopsy of the tumor in both eyes performed 1 month apart. A histopathologic diagnosis of the Rosai-Dorfman disease with focal areas of rhabdomyoblastic differentiation was made. He was treated postoperatively with a course of oral steroids with close observation for the rhabdomyoblastic differentiation. Rosai-Dorfman disease is an uncommon disease and has been reported to coexist with other pathologies. We highlight focal myoblastic differentiation within the excised tissues which may not necessarily warrant a diagnosis of rhabdomyosarcoma. Long-term follow-up of this patient is required to establish the safety of observation.