We describe a male patient, who was seen for the first time at the age of 8 years because of short trunk dwarfism. Spine radiographs showed platyspondyly with irregular areas of increased and decreased mineralization (irregular spotted appearance within lytic lesions located along the posterior vertebral bodies of the entire spine). Skeletal survey showed no enchondromatous lesions of the short/long tubular bones. At the age of 17, progressive spine stiffness associated with stooping posture developed. 3DCT scanning showed pathological transformation of the spinal enchondromas into generalized ossification and thickening of the posterior vertebral elements (vertebral laminae, supraspinal, and interspinal ligaments, respectively) causing effectively the development of a diffuse posterior spinal ankylosis. We report what might be a unique subtype of spondyloenchondrodysplasia (Spranger type IV).