Osteomyelitis of the Maxilla Secondary to Osteopetrosis: A Report of 2 Cases in Sisters

The incidence of osteomyelitis has dramatically reduced since the introduction of antibiotics. When it now occurs in Western society, the possibility of predisposing immunosuppressive conditions or underlying bony pathology should be considered. Osteomyelitis is a complication in 10% of cases of osteopetrosis. Osteopetrosis (marble bone disease, Albers-Schonberg disease, osteosclerosis fragilis generalisata) is a congenital sclerosing disease of bone caused by aberrant osteoclast mediated bone resorption. There is normal production of bone with lack of physiological resorption. The disease represents a spectrum of clinical variants because of the heterogeneity of genetic defects resulting in osteoclast dysfunction. Three clinically distinct forms are recognized: an infantile malignant autosomal recessive form, an intermediate autosomal recessive form, and an adult benign autosomal dominant form. Infantile malignant autosomal recessive osteopetrosis is diagnosed within the first year of life. Patients typically present with pathologic fracture or failure to thrive with frequent respiratory, head and neck, or bony infections. Physical examination shows lethargy, small stature, marked hepatosplenomegaly, and dysmorphic features including macrocephaly, frontal bossing, and hypertelorism. Neural palsies may occur, particularly affecting the optic, oculomotor, and facial nerves because of progressive thickening of bone at the expense of the neural canals. Intermediate autosomal recessive osteopetrosis is usually diagnosed toward the end of the first decade of life. Patients often present with pathological fracture. Clinical characteristics include delayed motor and cognitive development, mild disproportionate short stature, mild hepatosplenomegaly, and dysmorphic features such as macrocephaly and frontal bossing. Cranial nerve compression and mandibular osteomyelitis are common features. This form of osteopetrosis is rare. Most patients survive into adulthood but with significant disability. Autosomal dominant osteopetrosis (adult benign osteopetrosis) is a much milder condition. Patients have a normal life expectancy and many are asymptomatic. Patients may present in adulthood with recurrent fractures, back pain, bone pain, or osteomyelitis, particularly of the mandible. Cranial nerve palsies and osteoarthritis of the hips and knees are other potential features. Autosomal dominant osteopetrosis is divided into 2 radiological subtypes. In type I, cranial sclerosis and thickening affects mainly the calvarium. The calvarium is almost normal in type II, but the cranial base is sclerotic. Although both types involve generalized skeletal sclerosis, patients with the type II subtype have a higher risk for fractures.