 |
Case Reports |
Indian Pediatrics 2000;37: 98-99 |
Osteopetrorickets |
| Vikram Datta, Nirmal C. Prajapati,
Milind Kamble, Satish Pathak* From the Department of
Pediatrics and Radiology* M.G. Institute of Medical Sciences, Sevagram, Wardha 442 102,
India. Osteopetrosis is an inherited skeletal disease in which defective bone resorption by osteo-clasts leads to excessive bone deposition. Rickets is a paradoxical complication of in-fantile osteopetrosis and results from the inability of the osteoclasts to maintain a normal calcium-phosphorus balance in the extracellular fluid(1). We report a case of infantile osteo-petrosis complicated by rickets. Case Report A 12-month-old female child, product of a non-consanguineous marriage presented with gradually increasing abdominal distension, fever and cough of 1 month duration. On examina-tion, the child was wasted and stunted (all anthropometric parameters were less than 5th centile of NCHS). Developmental milestones were normal. The child was pale, hair were hypopigmented and sparse. There was frontal bossing, malar prominence, depressed nasal bridge, wide open anterior fontanelle, widening of wrists and prominence of the costochondral junction. Abdomen was distended with organo-megaly (both liver and spleen were 6 cm below costal margin). Respiratory, cardiovascular and neurological systems were normal. Investigations revealed: Hb-5.3 g/dl, TLC-9,200 cu/mm, platelets 1.2 lakh/cu mm, serum calcium 7.0 mg/dl, serum phosphorus 2.0 mg/dl and serum alkaline phosphatase 42 KA units. Serum potassium and arterial blood gases were normal. Radiological skeletal survey revealed diffuse bony sclerosis and bone in bone appearance in long bones (Fig. 1). These was notching of the anteriorthoracic lumbar spine, thickening and sclerosis of the bones of the base of the skull along with hypoplasia of the mandible, with no cerebral calcification. X-rays of wrist joint revealed metaphyseal fraying and cupping (Fig. 2).
Fig1. Radiograph of dorsolumbar spin with pelvis showing bony sclerosis along with rachitic changes.
Fig. 2. Radiograph of wrist showing bony sclerosis, bone in bone appearance, metaphyseal fraying and cupping. A diagnosis of osteopetrosis with super-imposed rickets was made based on the above radiological findings, serum calcium and phosphorus reports. The child was treated with 600,000 IU of Vitamin D3 and 200 mg/kg/day of elemental calcium orally. X-ray wrist done after 3 weeks of vitamin D3 administration did not reveal any signs of healing. Discussion Osteopetrosis is an extremely rare disease, with no sex predominance. Although the exact mechanism is not known, the disease is believed to result from genetic mutation. Rickets is paradoxical feature of infantile malignant osteopetrosis; despite a markedly positive total body calcium, the serum calcium and phosphorus product is insufficient to mineralize the newly formed chondroid and osteoid leading to rickets. The dysfunctional osteoclasts are unable to maintain a normal calcium phospho-rus balance in extracellular fluid despite a positive total body calcium balance. More than 99% of total body calcium is sequestered by the skeleton leading to a paradoxical decrease in the serum calcium and this decrease is often exacerbated by inadequate dietary intake of calcium(1,2). The excessive accumulation of osseous tissue increases bone density, constricts the marrow and neural foramen making the patient susceptible to anemia, leukopenia, thrombocytopenia, extramedullary hematopoie-sis and multiple cranial nerve palsies. In this child, during the radiological survey for rickets findings of osteopetrosis were co-incidentally noticed, which were later on confirmed on detailed skeletal survey. The association of rickets in patients with osteo-petrosis should be clearly identified at the onset for two reasons: (a) treatement of rickets leads to improvement in activity, decreases irritability, improves appetite and protects from recurrent respiratory tract infections(1,3); and (b) If facilities of bone marrow transplantation (BMT) are available, then for best results, rickets should be completely treated prior to this therapy(1). Rickets should be treated with Vitamin D3 and high levels of dietary calcium as it improves the general well being of the child(1). If associated with renal tubular acidosis, this condition should also be managed. Bone marrow transplantation is the only effective treatment for osteopetrosis; it provides hematopoietic stimulus that can differentiate into normal osteoclasts(1). Prognosis is uni-formly poor in absence of bone marrow trans-plantation, most of the children succumb to the disease by mild childhood due to anemia, bleeding and infections. Approximately 30% of patients survive upto 6 years of age. A few may live upto second or third decade. References 1. Kaplan FS, August CS, Fallon MD, Gannon F, Haddad JG. Osteopetrorickets: The paradox of plenty. Pathophysiology and treatment. Clin Orthop 1993; 294: 64-78. 2. Coccia PF, Krivit W, Cervenka J, Clawson C, Kersey JH, Kim HT et al. Successful bone-marrow transplantation for intantile malignant osteopetrosis. N Eng J Med 1980; 302: 701-708. 3. Banco R, Siefert MF, Marks SC, McGuire JL. Rickets and osteopetrosis: The osteosclerotic mouse. Clin Orthop 1985; 201: 238-242.
|
