Monostotic fibrous dysplasia of the spine is extremely rare. We present a 57-year-old man who complained of persistent low back pain with monostotic fibrous dysplasia of the lumbar spine. Computed tomography revealed a lytic expansile lesion and marginal sclerosis in the L2 posterior element, although a bone scan did not reveal increased uptake in the lesion. The patient underwent total excision of the tumor via a posterior approach. Two years later, he is asymptomatic with no recurrence of the lesion, as confirmed by imaging.