Fragile bone syndrome associated with craniognathic fibro-osseous lesions and abnormal modeling of the tubular bones: Report of two cases and review of the literature

Objective. To report examples of disorders characterized by bone fragility, calvarial and/or gnathic fibro-osseous lesions, and metadiaphyseal undermodeling of the tubular bones. Design. The clinical, radiological, and pathological features of two patients are described and the literature reviewed. Patients. The patients comprised a 10-year-old boy and a 48-year-old woman. The former: exhibited multiple fractures starting in early childhood and calvarial masses which developed in late childhood; the latter showed a mandibular mass. Results. Calvarial doughnut lesions, osteopenia with coarse bony trabeculae, and undermodeling of the lower limbs were radiologically demonstrated in the first patient, while multiple sclerotic foci in the maxilla and mandible, spontaneous bowing of the right femur, and minimal undermodeling of the tibiae were demonstrated in the second. Bone biopsy of the iliac crest in the first patient revealed histologically normal bony trabeculae. Bone histomorphometry suggested an increased osteoid surface. Osteoid volume was also slightly increased. The pathological findings of the mass in the jaw in the latter patient were consistent with it being a fibro-osseous lesion. The literature review revealed several patients whose features overlapped with those of our patients. Conclusion. These patients may represent a group of fragile bone syndromes which differ from osteogenesis imperfecta.