Genochondromatosis type II: report of a new patient and further delineation of the phenotype.

Enchondromas are common intraosseous usually benign cartilaginous tumors that develop in close proximity to growth plate cartilage. Genochondromatosis is a familial skeletal condition with autosomal dominant inheritance pattern. Genochondromatosis type I is a skeletal disorder characterized by symmetrical chondromatosis with characteristic localization: clavicle, upper end of humerus, and lower end of femur. The condition shows a benign course and is clearly different from metachondromatosis, generalized enchondromatosis, and spondyloenchondrodysplasia. In contrast, genochondromatosis type II is characterized by normal clavicles, but metaphyseal involvement of the hands, feet, knees, and wrists. To date, one family has been described with two affected individuals and possibly a second one with seven affected individuals. We report here on a boy with radiographic features of genochondromatosis type II. This report confirms that this disorder represents a separate clinical entity distinguishable for genochondromatosis type I. In addition, this report confirms the benign course of this rare disorder and will help accurate genetic counseling.