Monostotic fibrous dysplasia with involvement of the mandibular canal.

A 72-year-old woman sought treatment with a rare monostotic fibrous dysplasia occurring in the mandible and involving the mandibular canal. Her chief complaint was swelling, which had appeared about 2 years previously, had enlarged gradually, and was associated with spontaneous pain. X-ray film examination revealed a ground-glass opaque image of blurred demarcation, and 99mTc-methylene diphosphonate bone scintigraphy disclosed an area of marked radioisotope uptake. Histopathologic examination revealed the area of bone marrow and spongy bone to be replaced by fibrous tissue, irregular beam-shaped woven bone, and lamellar bone. Contouring of the expanded portion of the bone and surgical decompression of the mandibular canal were performed with good results.