Osteopetrosis

Malignant osteopetrosis (MI)
X-ray of the pelvis of a patient with osteopetrosis, adult onset form (Albers-Schönberg disease). Note the dense appearance
Classification and external resources
Specialty	medical genetics
ICD-10	Q78.2
ICD-9-CM	756.52
OMIM	166600 259700
DiseasesDB	9377
eMedicine	med/1692
Patient UK	Osteopetrosis
MeSH	D010022
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Three definite clinical forms of the disease, infantile, intermediate, and adult onset are recognized founded upon age and clinical features. In contrast to the infantile type with more intense manifestations, the adult onset type (Albers-Schönberg disease) is usually less pronounced clinically. Osteopetrosis, literally "stone bone", also known as marble bone disease, is an extremely rare inherited disorder whereby the bones harden, becoming denser, in contrast to more prevalent conditions like osteoporosis, in which the bones become less dense and more brittle, or osteomalacia, in which the bones soften. Osteopetrosis can cause bones to dissolve and break.

It can cause osteosclerosis.. It is considered to be prototype of osteosclerosing dysplasias. The cause of the disease is understood to be malfunctioning osteoclasts. Radiological findings will show a bone-in-bone appearance.

Despite this excess bone formation, people with osteopetrosis tend to have bones that are more brittle than normal. Mild osteopetrosis may cause no symptoms, and present no problems. However, serious forms can result in stunted growth, deformity, and increased likelihood of fractures; also, patients suffer anemia, recurrent infections, and hepatosplenomegaly due to bone expansion leading to bone marrow narrowing and extramedullary hematopoiesis. It can also result in blindness, facial paralysis, and deafness, due to the increased pressure put on the nerves by the extra bone.

Malignant infantile osteopetrosis or (Infantile autosomal recessive osteopetrosis) is a rare type of skeletal dysplasia characterized by a distinct radiographic pattern of overall increased density of the bones with fundamental involvement of the medullary portion. Infantile osteopetrosis typically manifests in infancy. Diagnosis is principally based on clinical and radiographic evaluation, confirmed by gene analysis where applicable. As a result of medullary canal obliteration and bony expansion, grave pancytopenia, cranial nerve compression, and pathologic fractures may ensue. The prognosis is poor if untreated. The classic radiographic features include, endobone or “bone-within-bone” appearance in the spine, pelvis and proximal femora, upper limbs and short tubular bones of the hand. Additionally, there is the Erlenmeyer flask deformity type 2 which is characterized by absence of normal diaphyseal metaphyseal modelling of the distal femora with abnormal radiographic appearance of trabecular bone and alternating radiolucent metaphyseal bands. The precise and early diagnosis of infantile osteopetrosis is important for management of complications, genetic counselling and timely institution of appropriate treatment namely hematopoietic stem cell transplantation. Hematopoietic stem cell transplantation offers a satisfactory treatment modality for a considerable percentage of infantile osteopetrosis. Amelioration of radiographic bone lesions after hematopoietic stem cell transplantation in infantile osteopetrosis have been proposed to be important indicators of success of hematopoietic stem cell transplantation. Few publications with limited study participants have demonstrated the resolution of skeletal radiographic pathology following hematopoietic stem cell transplantation.

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