Radiation-Induced CNS Pleomorphic Sarcoma after Adjuvant Therapy for Glioma

Background Central nervous system radiation-induced sarcomas (CRS) are rare tumors that arise as a result of adjuvant treatment for primary brain tumors. The incidence of CRS after radiation therapy is estimated to be less than 0.5%. The prognosis of CS is very poor, with the majority of patients expiring within months after diagnosis. There are several histopathologic subtypes that behave with different degrees of aggression. We present the first reported case of an undifferentiated high-grade pleomorphic sarcoma involving the calvarium, meninges, and brain parenchyma. This is an extremely rare subtype of radiation-induced sarcoma that occurred 12 years after his initial therapy.

Case Report A 54-year-old man who underwent resection of a left frontal anaplastic oligoastrocytoma in 2004 presented to our institution’s clinic in May 2016 complaining of swelling at his previous craniotomy site. The site of swelling was observed to be in the previous radiation field. He had received 5,940 cGy in fractionated radiotherapy after his surgical resection in 2004. A 5-cm lump was palpated under the skin, and the patient reported that it had significantly enlarged over the past month. MRI demonstrated an extra-axial enhancing mass that extended through the craniotomy site and into the subcutaneous tissues (Fig. 1). The lesion was completely resected (Fig. 2) and histopathologic testing revealed undifferentiated high-grade pleomorphic sarcoma (Fig. 3). The postoperative course was uncomplicated; however, the patient returned to clinic within a few weeks complaining of regrowth of the lesion. An MRI showed a new subcutaneous mass concerning for recurrence of the sarcoma with evidence of early hydrocephalus and leptomeningeal carcinomatosis (Fig. 4). The lesion was resected and pathology again showed undifferentiated high-grade pleomorphic sarcoma. In light of the poor prognosis and rapid growth of the tumor, the patient elected for palliative management and expired 3 months after his second surgery.

Conclusion CRS are rare but aggressive tumors that occur uncommonly after adjuvant treatment of primary brain tumors. The most common subtype of CRS is osteosarcoma; however, to our knowledge, this is the first reported case of radiation-induced undifferentiated pleomorphic sarcoma of the central nervous system. With the ongoing advances in radiation therapy over the past several decades, more patients are electing to undergo “conservative” management of primary brain tumors with radiation. It is important for both physicians and patients to be aware of this condition and understand the implications of acquiring postradiation sarcomas, as these tumors are very difficult to treat and carry a poor prognosis.

Fig. 1 T1-weighted MRI with contrast showing (A) axial and (B) coronal cuts with infiltrating and enhancing mass in the left frontal region extending from the subcutaneous tissues into the brain parenchyma.

Fig. 2 Postoperative (A) axial and (B) coronal T1-weighted MRI with contrast.

Fig. 3 Pathology slides showing (A) dural invasion, (B) marked pleomorphism, and (C) temporalis invasion.

Fig. 4 Subsequent T1-weighted MRI with contrast showing (A) coronal and (B) axial cuts with left frontal enhancing lesion with hydrocephalus concerning for recurrent sarcoma with leptomeningeal progression.