Fibrous dysplasia localized to spine: a diagnostic dilemma.

Fibrous dysplasia of the spine is uncommon, especially in monostotic form. Isolated vertebral involvement in polyostotic form is very rare. We report a case of polyostotic fibrous dysplasia with lesions localized to dorso-lumbar spine in a 45-year-old rheumatoid arthritis patient. No associated appendicular lesions, cutaneous manifestations or endocrinopathies were seen. The extreme rarity of this type of lesion can pose a diagnostic dilemma, and biopsy is required for diagnosis. The association with rheumatoid arthritis in our case seems to be a chance occurrence.