Recurrent benign osteoblastoma of the parietal bone

A huge occipital osteoblastoma accompanied with aneurysmal bone cyst in the posterior cranial fossa

Osteoblastoma is an infrequent benign tumor and skull involvement is extremely rare. The occipital bone is much less frequently involved. We report an unusual case of a huge occipital osteoblastoma with aneurysmal bone cyst in the posterior cranial fossa of a 20-year-old young man. MRI scan and CT three-dimensional reconstruction revealed that the tumor (approximately 8.5 cm x 6 cm x 5 cm) occupied nearly half volume of the posterior cranial fossa. The cerebellum, the forth ventricle and brain stem were compressed remarkably and hydrocephalus was noted. The tumor mass was multiloculated cystic and highly vascular. Excessive bleeding occurred during operation and total removal was achieved. The patient was symptom-free and MRI scan revealed no evidence of recrudescence after a follow-up period of 18 months. Pathological examination revealed that the lesion was a benign osteoblastoma with secondary aneurysmal bone cyst (ABC). ABC constitutes a highly vascular lesion while complete surgical resection is often impeded by excessive intraoperative bleeding. Preoperative embolization may reduce the risk. Despite the benign nature of osteoblastoma, local recurrence after incomplete resection is not rare and malignant transformation during recurrence may occur even after adequate surgery. Our case confirms the findings of previous investigators that if osteoblastoma is removed completely, no recurrence is expected even without adjuvant irradiation and chemotherapy.

Occipitoparietal benign osteoblastoma: should entire lesion be resected when magnetic resonance images reveal wide abnormal signal intensity in surrounding bone marrow?

BACKGROUND

Benign osteoblastoma is an uncommon primary bone tumor that usually affects long bones and the vertebral column. Its occurrence in the calvarium is rare. Despite the characteristically benign nomenclature of osteoblastoma, it sometimes recurs with the possibility of transforming into a malignant form after an incomplete resection. Therefore, radical resection is recommended whenever possible. However, it has not been clarified whether the adjacent bones should also be completely resected when magnetic resonance (MR) images reveal abnormal signal intensity in the bone marrow.

CASE DESCRIPTION

Presented in this case report is a 12-year-old boy with occipital tenderness associated with occipitoparietal bone tumor. Neuroradiological studies demonstrated a solid tumor located in the occipital bone extending over the right parietal bone. Magnetic resonance images further revealed abnormal signal intensity in the bone marrow of the entire occipital and bilateral parietal bones. Macroscopically, the calvarial bone adjacent to the solid tumor appeared to be reddish, but it was not covering the entire area, contradicting the abnormal intensity found on the preoperative MR images. The resected area was determined according to macroscopic findings, and bones with normal color tone were preserved. Because histological examination did not clearly indicate tumor invasion at the margin of the resection site, no additional therapy was given. Although MR images revealed abnormal intensity in the bone marrow of the surgical margin immediately after the operation, the intensity had been normalized by degrees and there was no evidence of recurrence during a follow-up period of 34 months. This may suggest that bone marrow lesion showing abnormal intensity was edema rather than tumor invasion.

CONCLUSIONS

The authors conclude that total resection, including a bone marrow lesion, is not always necessary for benign osteoblastoma. Macroscopic findings that show an abnormal color tone of the cortex could be a good indicator in revealing tumor activity invading bone marrow.

Giant osteoblastoma of temporal bone. Case report

Benign osteoblastoma is an uncommon bone tumor accounting for approximately 1% of all bone tumors. There are only 35 cases of skull osteoblastoma reported in the literature. We describe the case of a 23 year old male with a giant osteoblastoma of temporal bone submitted to a total removal of the tumor after an effective embolization of all external carotid branches. The authors discuss diagnostic and management aspects of this uncommon skull tumor.

Osteoblastoma of the calvaria: report of two cases diagnosed with MRI and clinical review

The authors describe 2 cases of osteoblastoma of the calvaria and review the clinical features of the 28 cases reported in the world literature. Benign osteoblastoma is a rare tumor that effects young patients, most frequently at temporal level. On the basis of its neuroradiological appearance, it is difficult to formulate a differential diagnosis against other osteoblastic tumors or against osteoid osteoma. In only a few cases MRI findings are reported. In our cases, MRI was more effective than CT scans and radiographs for evaluating the intracranial and intraosseous extension of the tumor. The definitive diagnosis was obtained by combining the histopathological features of the tumor with the clinical and radiological data. The prognosis of this tumor is very good regardless of the type of treatment performed, although both relapse and, more rarely, malignant tumor evolution are possible.

Unusual osteolytic midline lesion of the skull: benign osteoblastoma of the parietal bone

The authors report the case of a 5-year-old girl who presented with a parietal midline sub-scalp lesion. Skull radiographs demonstrated a lytic lesion surrounded by a sclerotic rim that resembled a dermoid cyst of the cranium. Histopathological analysis proved that the lesion was a benign osteoblastoma. As in other calvarial masses of uncertain nature, after diagnostic workup, we recommend surgical excision both for diagnosis and for treatment.

Benign osteoblastoma of the temporal bone: MRI

We investigated a 27-year-old woman with a retroauricular tumour. MRI revealed a signal void on T1 and T2-weighted images, and irregular enhancement with gadolinium-DTPA. The underlying dura mater also enhanced. The tumour was resected completely, and histological examination showed a benign osteoblastoma.

Benign osteoblastoma of the parietal bone

A 5-year-old girl presented with a 1-year history of a subcutaneous swelling in the right parietal region. There were no cerebral symptoms or signs. Plain X-ray of the skull showed a lytic bony lesion with sclerotic margin. Computed tomography showed a hypodense, osteolytic lesion with thinned and bulged inner and outer skull tables with intact continuity. There was no intracranial lesion. At operation, the mass was found to be pink and granular, and was totally enucleated. Histology revealed it to be a benign osteoblastoma.