[Parosteal osteosarcomas: unusual findings]. / Osteosarcomas parostales: resultados infrecuentes.

OBJECTIVE: To study and evaluate the unusual findings in the natural history of parosteal osteosarcomas. Parosteal osteosarcomas are well-differentiated tumours of low grade malignancy, but may dedifferentiate into a more aggressive lesion. MATERIAL AND METHODS: We reviewed 7 parosteal osteosarcomas treated in La Paz Hospital between 2005 and 2009 (3 were dedifferentiated parosteal osteosarcomas). The authors analysed the clinical and radiological features, histology, treatment and outcomes in this patient group. RESULTS: There were 5 men and 2 women, with a mean age of 32.14 years, range 24-47 years. Three of seven tumours (42.8%) were dedifferentiated osteosarcomas. All three patients received chemotherapy. One patient presented with pulmonary metastases. No patient died. CONCLUSIONS: It is important to understand that the biological phenomenon of dedifferentiation can occur in parosteal osteosarcomas. The prognosis, treatment and survival changes radically.

Hepatoerythropoietic porphyria due to a novel mutation in the uroporphyrinogen decarboxylase gene.

BACKGROUND: Hepatoerythropoietic porphyria (HEP) is a rare form of porphyria that results from a deficiency of uroporphyrinogen decarboxylase (UROD). The disease is caused by homoallelism or heteroallelism for mutations in the UROD gene. OBJECTIVE: To study a 19-year-old woman from Equatorial Guinea, one of the few cases of HEP of African descent and to characterize a new mutation causing HEP. METHODS: Excretion of porphyrins and residual UROD activity in erythrocytes were measured and compared with those of other patients with HEP. The UROD gene of the proband was sequenced and a new mutation identified. The recombinant UROD protein was purified and assayed for enzymatic activity. The change of amino acid mapped to the UROD protein and the functional consequences were predicted. RESULTS: The patient presented a novel homozygous G170D missense mutation. Porphyrin excretion showed an atypical pattern in stool with a high pentaporphyrin III to isocoproporphyrin ratio. Erythrocyte UROD activity was 42% of normal and higher than the activity found in patients with HEP with a G281E mutation. The recombinant UROD protein showed a relative activity of 17% and 60% of wild-type to uroporphyrinogen I and III respectively. Molecular modelling showed that glycine 170 is located on the dimer interface of UROD, in a loop containing residues 167-172 that are critical for optimal enzymatic activity and that the carboxyl side chain from aspartic acid is predicted to cause negative interactions between the protein and the substrate. CONCLUSIONS: The results emphasize the complex relationship between the genetic defects and the biochemical phenotype in homozygous porphyria.

Recambio mineral óseo y densitometría ósea en pacientes sometidos a dieta de riesgo: hiperfenilalaninemia y galactosemia. Respuesta del autor / Bone mineral turnover and bone densitometry in patients with dietary risk: hyperphenylalaninemia and galactosemia. Author’s response

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[Bone mineral turnover and bone densitometry in patients with a high-risk diet: hyperphenylalaninemia and galactosemia]. / Recambio mineral óseo y densitometría ósea en pacientes sometidos a dieta de riesgo: hiperfenilalaninemia y galactosemia.

INTRODUCTION: Patients with any type of congenital metabolism error are at risk for developing osteoporosis. To gain further insight into the physiopathology of this disease, we studied bone mineral turnover in 10 children with hyperphenylalaninemia, seven with phenylketonuria and six with galactosemia. Oral intake was strictly controlled and the children followed recommendations for physical exercise. MATERIAL AND METHOD: Markers of bone resorption (hydroxyproline and pyridinoline in urine samples) and markers of bone formation (levels of osteocalcin and C-terminal procollagen peptide type I) were analyzed. Bone mineral density was analyzed by ultrasound densitometry. RESULTS: A non-significant reduction in bone densitometry with respect to the normal population was observed. Bone mineral turnover was slightly diminished in patients with phenylketonuria but was within the normal range in patients with hyperphenylalaninemia and galactosemia. CONCLUSION: Adequate control of dietary intake of both proteins and minerals, as well as a healthy lifestyle, can prevent the development of significant alterations in bone mineralization.

Recambio mineral óseo y densiometría ósea en pacientes sometidos a dieta de riesgo: hiperfenilalaninemia y galactosemia / Bone mineral turnover and bone densitometry in patients with high-risk diet: hyperphenylalaninemia and galactosemia

Introducción. Con el fin de conocer mejor la fisiopatología de la osteoporosis que tienen riesgo de desarrollar los pacientes afectados de algunos errores congénitos del metabolismo se ha estudiado el recambio mineral óseo en 10 niños afectados de hiperfenilalaninemia media, siete de fenilcetonuria y seis de galactosemia, con un control estricto de la ingesta y unas recomendaciones de ejercicio físico adecuadas. Material y método. Se han analizando marcadores de resorción ósea, hidroxiprolina y piridinolina urinaria y de aposición ósea, osteocalcina y propéptido C terminal sérico. La densidad mineral ósea se ha analizado mediante densitometría por ultrasonidos. Resultados. Se objetiva que la densitometría ósea está disminuida respecto a la población normal sin llegar a ser estadísticamente significativo. El recambio mineral óseo está ligeramente disminuido en pacientes con fenilcetonuria, mientras que se encuentra dentro del rango de normalidad en pacientes con hiperfenilalaninemia media y galactosemia. Conclusión. El adecuado control de la ingesta dietética, tanto proteica como mineral, así como del régimen de vida saludable pueden prevenir la aparición de alteraciones significativas de la mineralización ósea

Introduction. Patients with any type of congenital metabolism error are at risk for developing osteoporosis. To gain further insight into the physiopathology of this disease, we studied bone mineral turnover in 10 children with hyperphenylalaninemia, seven with phenylketonuria and six with galactosemia. Oral intake was strictly controlled and the children followed recommendations for physical exercise. Material and method. Markers of bone resorption (hydroxyproline and pyridinoline in urine samples) and markers of bone formation (levels of osteocalcin and C-terminal procollagen peptide type I) were analyzed. Bone mineral density was analyzed by ultrasound densitometry. Results. A non-significant reduction in bone densitometry with respect to the normal population was observed. Bone mineral turnover was slightly diminished in patients with phenylketonuria but was within the normal range in patients with hyperphenylalaninemia and galactosemia. Conclusion. Adequate control of dietary intake of both proteins and minerals, as well as a healthy lifestyle, can prevent the development of significant alterations in bone mineralization

Valores normales de los marcadores del recambio óseo durante la infancia / Normal values of bone turnover markers in childhood

Objetivo: Obtener el perfil normal de los marcadores del recambio óseo durante la infancia para poder valorar el estado de mineralización ósea de la población infantil normal y de la población de riesgo para osteoporosis. Pacientes y métodos: Se ha estudiado una población de 75 niños sanos de entre 6 meses y 14 años de edad. Se han determinado en suero los valores de osteocalcina y de propéptido carboxiterminal del procolágeno tipo I como marcadores de aposición ósea y de la hidroxiprolina y las piridinolinas en orina, como marcadores de resorción ósea. Se ha realizado el análisis estadístico de los resultados. Resultados: Los valores más elevados para estos marcadores se han obtenido en los primeros 4 años de vida. A continuación los de resorción ósea presentan una continua disminución estadísticamente significativa hasta los 14 años de edad (p < 0,05), mientras que los de aposición ósea descienden ligeramente a partir de los 4 años y se mantienen posteriormente estables hasta los 14 años. Discusión: Este comportamiento es compatible con la presencia de un intenso recambio óseo durante los 4 primeros años, y con un predominio de los fenómenos de aposición ósea a lo largo de los primeros 14 años de vida. El conocimiento de los valores normales de dichos marcadores permite valorar el estado de la mineralización ósea de la población infantil normal y de la población de riesgo para osteoporosis (AU)

Limb salvage procedures in osteosarcomas around the knee joint.

Surgical techniques developed for restoring skeletal continuity after a local resection of a bone tumor (limb salvage procedures) revolutionized the management of the patient suffering from osteosarcomas around the knee. In this article the authors review the current status of various reconstruction procedures; they include osteoarticular allograft arthrodesis, rotation plasty, expandable prosthesis and knee arthroplasty. In summary they suggest that the knee arthrodesis is the preferred procedure for young and active patients, the rotation plasty should be recommended as the alternative to amputation for very young patients, and the customized prostheses are preferred for patients with limited longevity.