Atypical intraosseous osteolytic meningioma mimicking calvarial metastasis

Atypical intradiploic meningioma: A case report and review of the literature

Background:

Intradiploic meningiomas with osteolytic bony changes are rarely reported in the literature. Intradiploic meningiomas are usually slow-growing benign lesions but atypical histopathology predicts aggressive behavior. Atypical intradiploic meningiomas (WHO Grade II) have some controversies in the management which are highlighted in this article.

Case Description:

A 40-year-old male, with a history of trauma to the head 12 years back, presented with a hard, slow-growing painless swelling exactly at the site of trauma. On imaging, lesion was intradiploic one with osteolytic margins and homogeneously enhancing on contrast magnetic resonance imaging. Biopsy was that of atypical meningioma (WHO Grade II).

Conclusion:

Atypical meningiomas with osteolytic changes are rarely reported in the literature. Because of potential aggressive behavior, they need a regular follow-up with radiological imaging.

Primary intraosseous meningioma of the calvarium: A systematic review

BACKGROUND

Primary intraosseous meningiomas (PIM) of calvarial origin are a small subset of meningiomas that arise from and occur within the calvarial bone. Its definition is often confused with other forms of non-dural based intracranial meningiomas, which has made previously published retrospective reviews heterogenous, non-specific and sometimes inaccurate. We present a systematic review of calvarial PIM.

METHODS

Using a systematic search protocol that included databases such as PubMed, Web of Science and Embase, we extracted all human studies on PIM published from inception to December 2017. This systematic review includes case reports and retrospective reviews that specifically described PIM.

RESULTS

On review of 166 articles identified with the systematic search protocol, 69 articles were analyzed. These comprised of 64 case reports, 1 case series and 4 retrospective reviews. 111 patients with PIM of calvarial origin were analyzed, 58 % of which were females and 42 % males. The mean patient age was 51 years and the frontal bone was the most common tumor location, occurring in 26.1 % of the cases. Surgical resection was the predominant modality of treatment in 97.2 % of the cases, and gross total resection was achieved in 84 % of cases that reported extent of resection. There were no recurrences for grade I meningiomas. However, all grade III meningiomas recurred and 33.3 % of grade II meningiomas showed recurrence with a mean postoperative follow-up interval of 20 months. Statistical analysis using Fisher's exact test showed the recurrence rate to be strongly associated with WHO tumor grade (p-value <0.001).

CONCLUSION

There is statistically significant increased recurrence rate for calvarial PIM of higher grades, and we recommend close follow-up in those cases. Surgical resection remains the overwhelming treatment of choice for calvarial PIM, and it has a high gross total resection rate and low risk of complications and mortality.