Periosteal chondroma.

Periosteal chondroma is an uncommon benign cartilagenous lesion, and its importance lies primarily in its characteristic radiographic and pathologic appearance which should be of assistance in the differential diagnosis of eccentric lesions of bones. The pathologist must be aware of this tumour because at a histologic level, it may closely resemble a more ominous cartilagenous lesion. He can exclude this lesion in a differential diagnosis of a primary cartilagenous bone neoplasm by familiarity with the clinical and radiological appearance of the lesion. In all cases reported so far, treatment has been that of wide local excision. There are no recorded cases of metastases in follow-up periods ranging up to 8 years after surgery. In those cases where local recurrences were reported, inadequate initial excision is the admitted cause, and subsequent re-excision led to complete eradication of the residual tumour.