Osteopetrosis (Marble Bone Disease): A Rare Disease in Children

Osteomyelitis Possibly Caused by Exfoliation of Primary Teeth in a Patient with Osteopetrosis

Osteopetrosis is a rare inherited skeletal disease characterized by increased density in the bones and can be detected by radiographs. Sclerosis makes the jaw bones extremely susceptible to infections, osteomyelitis, and fractures. Here, we report a case of osteomyelitis possibly caused by spontaneous exfoliation of primary teeth in a patient with osteopetrosis. A 2 years and 9 months (2Y9M)-old boy with osteopetrosis was referred to our clinic for oral management. Only four primary central incisors had erupted, and they all exhibited hypoplasia. The mandibular right central primary incisor suddenly became exfoliated at 4 years and 1 month. The mandibular right lateral primary incisor also became exfoliated at 4 years and 3 months, soon after eruption, and the mandibular left central primary incisor became exfoliated at 4 years and 5 months. Subsequently, we confirmed the eruption of calcified tissue at 4 years and 9 months in the location where the mandibular right lateral primary incisor had become exfoliated. The patient was admitted to the pediatrics clinic for mandibular cellulitis at 5 years and 2 months, then referred to our clinic for the management of osteomyelitis. The patient's acute inflammation was reduced by repeated irrigation and the administration of antibiotics; the inflammation gradually became chronic. When treating patients with osteopetrosis, dentists and oral surgeons should prioritize infection control in the jaw, periodic assessment of dental eruption, and the maintenance of oral hygiene.

Phenotype-autosomal recessive osteopetrosis

Osteopetrosis (OPT) is a life-threatening disease characterized by increased bone mass caused by diminished osteoclast function/differentiation. The autosomal recessive forms, caused by biallelic variants in implicated genes, usually present in infancy. Without treatment, autosomal recessive OPTs are usually fatal within the first 10 years of life [1]. Here, we review the clinical features and associated pathophysiology of the autosomal recessive OPT. A greater understanding of these rare disorders will advance early diagnosis and optimal management.

Progressive skeletal defects caused by Kindlin3 deficiency, a model of autosomal recessive osteopetrosis in humans

The cellular and molecular mechanisms of bone development and homeostasis are clinically important, but not fully understood. Mutations in integrins and Kindlin3 in humans known as Leukocyte adhesion deficiencies (LAD) cause a wide spectrum of complications, including osteopetrosis. Yet, the rarity, frequent misdiagnosis, and lethality of LAD preclude mechanistic analysis of skeletal abnormalities in these patients. Here, using inducible and constitutive tissue-specific Kindlin3 knockout (K3KO) mice, we show that the constitutive lack of embryonic-Kindlin3 in myeloid lineage cells causes growth retardation, edentulism, and skull deformity indicative of hydrocephaly. Micro-CT analysis revealed craniosynostosis, choanal stenosis, and micrognathia along with other skeletal abnormalities characteristic of osteopetrosis. A marked progression of osteosclerosis occurs in mature to middle-aged adults, resulting in the narrowing of cranial nerve foramina and bone marrow cavities of long bones. However, postnatal-Kindlin3 is less critical for bone remodeling and architecture. Thus, myeloid Kindlin3 is essential for skeletal development and its deficiency leads to autosomal recessive osteopetrosis (ARO). The study will aid in the diagnosis, management, and treatment choices for patients with LAD-III and ARO.