Parasagittal cranial fasciitis following infratemporal fossa rhabdomyosarcoma

Cranial fasciitis is a rare lesion of young children characterized by proliferation of fibroblastic spindle cells. Most are scalp masses and are only rarely intracranial, where an association with radiation therapy is exceptional. We report a 32-month-old toddler with a facial rhabdomyosarcoma, diagnosed at 3 months of age, and treated with surgery, chemotherapy and brachytherapy. Brain MRI at 28 months revealed a large, left parasagittal, dural-based, T2 hyperintense and T1 hypointense enhancing mass with superior sagittal sinus compression and bony hyperostosis. The mass was completely resected during an open craniotomy. Histologically, the lesion was comprised of loosely and haphazardly arranged bland spindle cells embedded in a myxoid background. Thick hyalinized collagen bundles were especially prominent. The spindle cells reacted for vimentin but not SMA, myogenin, MyoD1 or EMA. A diagnosis of cranial fasciitis was rendered. The role of radiation therapy in the pathogenesis of intracranial cranial fasciitis is discussed.