THE CLUSTER OF ARACHNOID DIVERTICULA IN THE OCCIPITAL BONE - REPORT OF 2 CASES WITH LITERATURE-REVIEW

The authors report two cases of multicentric osteolytic lesions in the occipital bone without any history of head trauma. The excisional bio psy of the first case revealed that the lesion was multicentric but a continuous cavity with the subarachnoid space through various sizes of dural defect, and the cavities were covered by arachnoid lining. Toge ther with the previously reported similar 5 cases, the characteristic common feature is multicentric osteolytic lesions in the occipital bon e at advanced age without marginal sclerosis. ''The cluster of arachno id diverticula in the occipital bone (CADOB)'' is probably the most ap propriate term for these non-traumatic lesions with the following char acteristics: elderly patients, occipital bone, midline, multiple, inta ct outer table, nonsclerotic margin and without history of trauma. Ope ration may not be indicated because of its non-progressive and benign nature.