Achondroplasia and enchondromatosis in a female child

Achondroplasia manifesting as enchondromatosis and ossification of the spinal ligaments: a case report

Introduction

A girl presented with achondroplasia manifested as mild knee pain associated with stiffness of her back. A skeletal survey showed enchondroma-like metaphyseal dysplasia and ossification of the spinal ligaments. Magnetic resonance imaging of the spine further clarified the pathological composites.

Case presentation

A 7-year-old girl presented with the classical phenotypic features of achondroplasia. Radiographic documentation showed the co-existence of metaphyseal enchondromatosis and development of spinal bony ankylosis. Magnetic resonance imaging showed extensive ossification of the anterior and posterior spinal ligaments. Additional features revealed by magnetic resonance imaging included calcification of the peripheral vertebral bodies associated with anterior end-plate irregularities.

Conclusion

Enchondromas are metabolically active and may continue to grow and evolve throughout the patient's lifetime; thus, progressive calcification over a period of years is not unusual. Ossification of the spinal ligaments has a specific site of predilection and often occurs in combination with senile ankylosing vertebral hyperostosis. Nevertheless, ossification of the spinal ligaments has been encountered in children with syndromic malformation complex. It is a multifactorial disease in which complex genetic and environmental factors interact, potentially leading to chronic pressure on the spinal cord and nerve roots with subsequent development of myeloradiculopathy. Our patient presented with a combination of achondroplasia, enchondroma-like metaphyseal dysplasia and calcification of the spinal ligaments. We suggest that the development of heterotopic bone formation along the spinal ligaments had occurred through an abnormal ossified enchondral mechanism. We postulate that ossification of the spinal ligaments and metaphyseal enchondromatous changes are related to each other and represent impaired terminal differentiation of chondrocytes in this particular case. Standard radiographic examination showed spinal bony ankylosis only. The pathological composites of the vertebrae have been clarified using scanning technology. Extensive spinal ligament ossification associated with calcification of the peripheral vertebral bodies and anterior end-plate irregularities were notable. We report what may be a novel spinal and extraspinal malformation complex in a girl with achondroplasia.

Achondroplasia and enchondromatosis: report of three boys

We report on three boys suffering from achondroplasia concurrent with enchondromatosis-like metaphyseal changes. Two boys who were examined by molecular analysis harbored a mutation of FGFR3, which occurs in most achondroplastic individuals. Given the prevalence of achondroplasia and enchondromatosis, the metaphyseal changes in these patients are less likely to represent the coincidence of both disorders, but rather to result from a rare consequence of the FGFR3 mutation. Impaired FGFs/FGFR3 signaling pathway in achondroplasia inhibits chondrocytic proliferation, which accounts for most characteristics of achondroplasia. On the other hand, it causes conflicting biological consequences that can suppress or stimulate chondrocytic maturation. In a small subset of achondroplastic individuals, the suppression of chondrocytic maturation may outweigh the stimulation, which leads to cartilaginous overgrowth into the metaphysis, eventually causing the metaphyseal dysplasia found in the present patients.