RESUMO

Congenital pseudoarthrosis of the tibia (CPT) is an uncommon disease whose etiology and pathogenesis is unknown. Several evidences suggest that decreased osteogenic capacities, impaired local vascularization, and microenvironment alterations may play a role in the pathogenesis of CPT. Additionally, it is not clear if the pathogenesis of this disease is related to the absence of cells with osteogenic capacity of differentiation. In this work, a two-year-old patient diagnosed with CPT underwent an orthopedic surgery to promote bone union in a pseudoarthrosis lesion. Tissue from CPT lesion was excised, and histological evaluation and tissue culture were performed. Histologic analysis of the soft CPT lesion showed the presence of highly cellular fibrous tissue, vascularization, and abundant extracellular matrix. Fusiform cells of mesenchymal appearance were observed but osteoblasts, osteoclasts, chondrocytes, and adipose cells were not found. There was no evidence of osteogenesis. CPT tissue cultured as explants showed, after one month of culture, evidence of osteogenesis, chondrogenesis, and adipogenesis. Cells isolated from explants of CPT tissue showed a fibroblast-like morphology and expressed the mesenchymal stromal cell (MSC) markers: CD105, CD73, and CD90 (CPT-MSC). Functional analysis showed that CPT-MSC differentiate, in vitro, into osteogenic, chondrogenic, and adipocytic cells. CPT-MSC expressed osteocalcin and agrecan. CPT-MSC produced collagen in the presence of ascorbic acid. MSC from BM of normal individuals were used as control. In summary, our results indicate that CPT tissue contains MSC with osteogenic capacity of differentiation. It is possible that CPT microenvironment may contribute to impair the osteogenic capacity of differentiation of CPT-MSC.

Assuntos

RESUMO

Reportar la frecuencia de los tumores óseos orbitarios. En un período de ocho años (1998-2005) se realizaron 117 899 biopsias en el Instituto Anatomopatológico "Dr. J. A. O’Daly" de la Universidad Central de Venezuela, de las cuales se identificaron 1 826 biopsias óseas, de las cuales 17 (0,93 por ciento) correspondieron a tumores óseos orbitarios. Se investigaron las variables edad, sexo, localización y tipo de neoplasia. En la revisión se identificaron 10 tumores óseos primarios (8 benignos y 2 malignos), 6 casos de pseudotumores (35 por ciento) y un tumor metastásico (6 por ciento). El osteoma y la displasia fibrosa fueron las condiciones más frecuentes. Los tumores óseos primarios de la órbita son un grupo heterogéneo de condiciones que constituyen el 0,6 por ciento - 2 por ciento de todos los tumores orbitarios.

To evaluate the rate of orbital bone tumours. Our experience over a 8-year period in Instituto Anatomopatologico "Dr. J. A. O’Daly" at the Universidad Central de Venezuela, yielded 17 (0.93 percent) cases of orbital bone tumours from a total of 117 899 biopsies. Data were collected on patient age, sex, tumour localization and type of neoplastic disorders. Results: Ten cases (59 percent) were primary tumours of orbital bone (8 benign and 2 malignant), six patients with tumour-like lesions (35 percent) and one bone metastases. The two most commonly encountered entities were osteoma and fibrous dysplasia. Primary tumours of orbital bone constitute 0,6 percent - 2 percent of all orbital tumours.

Assuntos