Teaching Case

Routine imaging follow up after treatment of sinonasal cancer

Middle age patient treated for a cancer of the facial area by surgery and external irradiation. No neurological symptoms. Systematic follow up CT and MR are presented.

Post irradiation meningioma are a late and rare manifestation of irradiation (1). They can be either associated with low-dose x-ray therapy such as individuals treated in childhood for tinea capitis (2), or with high-dose cranial irradiation (3). The average time from radiation therapy to diagnosis is around 25 years (range 5 to 40 years (3) for high dose irradiation; the with interval is longer in meningiomas induced by lower doses of irradiation (2). These tumors have distinct characteristics: their location at the site of maximal irradiation, and features suggesting rapid growth and aggressive biological behavior (2). There is a significantly higher number of calvarial tumors, a high proportion of multiple meningiomas, a higher recurrence rate following apparent complete , and an increased number of histologically malignant meningiomas (2). MR is the imaging modality of choice (4): the aggressive behavior of radiation induced meningiomas helps to differentiate them from spontaneous meningiomas which usually present as well marginated lesions. Rapid growth and multiple location can also help to anticipate the correct diagnosis.