PMC3162981_01
AP view of skull xp (a) showing the bony defect of the left occipital lesion. Bone image CT at the level of the subcutaneous mass (b) demonstrating the bony defect of the left occipital bone without a change in the intraaxial lesion. The skull surface of the defective part was swollen. Axial T1-weighted MRI with contrast medium (c) showing a cystic change corresponding to the bony defect and partial enhancement around the cystic change. 99mTc-HMDP bone scintigraphy (d) showing accumulation of tracer in the part of the bone cyst corresponding to the strongly enhanced lesion found on MRI. Head DSA study (e, lateral view) demonstrating no abnormal vessels, including tumor feeder or aneurysmal changes.
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fig1
Upon admission, a subcutaneous mass with the same hardness as bone was found, which was palpable on the left occipital bone, and head xp showed a corresponding bone transmission image at the same lesion (Figure 1(a)). CT demonstrated a corresponding image of a bony defect and swelling of the outer table of the skull (Figure 1(b)). MRI revealed a corresponding bony defect and swelling at the subcutaneous tumor mass with cystic changes in the cavity of the bony defect, and a contrast study showed a partial enhancement around the cystic change (Figure 1(c)). 99mTc-HMDP bone scintigraphy demonstrated strong accumulation at a part of the cystic lesion (Figure 1(d)), and head DSA study revealed no tumor stain or feeder (Figure 1(e)).
Intraoperative photographs (a-d). Photograph of the skin immediately above the skull mass (a) showing the cutaneous scar (arrowheads) from the past injury. The skull surface just below the skin scar was smooth but swollen (b). Photograph obtained after piercing the cyst (c) demonstrating bloody cyst fluid and the inner surface of the cyst wall with no obvious tumorous change. Intact dura mater was observed after total removal of the skull mass (d).
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A cutaneous scar due to past injury was observed at the surface of skin immediately above the skull mass (Figure 2(a), arrowheads). The outer table of the skull beneath the skin of the scar was smooth without fracture but swollen (Figure 2(b)). The dura mater and brain tissue just below the bony cyst was intact (Figure 2(d)).
Postoperative AP view of skull xp (a) and bone image with head CT (b) showing complete resection of the tumor and excellent remodeling of the skull deficit using calcium phosphate paste. Microscopic view of the intraoperative biopsied specimen (c, H&E stain, x200). The lesion was composed of irregularly shaped trabeculae of woven bone with calcification in a background of fibrous tissue. There were no osteoblasts on the surface of the trabeculae. These histological findings were indicative of fibrous dysplasia.
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fig3
Postoperative xp and CT showed that the tumor mass had been completely removed, and cranioplasty of the bone deficit after tumor removal was successful (Figures 3(a) and 3(b)). Results of a pathological examination by H&E staining demonstrated an FD tissue image in a region where strong technetium accumulation was observed (Figure 3(c)).