Solitary Epiphysial Enchondroma of the Proximal Humerus Causing Growth Deficiency in a 13-Year-Old Boy Lengthened over Intramedullary Nail

A 13-year-old boy complained of shortness of his left arm with the desire for lengthening. The X-Ray showed the enlarged ellipsoid shaped humeral epiphysis in varus position and irregular joint surface. The MRI documented a distorted bone structure involving the complete epiphysis, overgrowth of the tuberosities and partial closure of the physis. MR-angiography revealed normally appearing vessel formation; however, a biopsy was recommended to rule out a vascular malformation. A tru-cut needle biopsy confirmed the diagnosis of enchondromatous changes. As the patient felt strongly disturbed by the shortness of his arm, lengthening was performed using the fully inserted magnetic driven PreciceR nail. Conclusion: This case is of interest as epiphysial enchondromas are rare and complete involvement of the proximal humeral epiphysis causing growth deficiency to our knowledge has never been described before. Lengthening using a device penetrating the cartilaginous region is debatable; however, so far, sarcomatous dedifferentiation in epiphysial enchondromas has not been described.