Radiological complete response in diffuse intrinsic pontine glioma: a case report

The prognosis of DIPG is still dismal. Despite transient clinical improvement after treatment, there is usually minimal or no radiologic regression and radiological complete response is very rare. Here, we report a child with DIPG who had radiological complete response and long-term survival treated with radiotherapy and adjuvant temozolomide. The initial MRI of a 9-year-old boy demonstrated large pontine mass causing expansion with the largest diameter of 35 mm, partially encasing the basilar artery and indenting the anterior wall of the 4th ventricle suggestive of DIPG. He received radiotherapy concomitant temozolomide orally 75 mg/m²/day during radiotherapy. Six weeks after radiotherapy, the MRI revealed significant reduction in the size of the pontine mass. Treatment was followed by oral temozolomide 200 mg/m²/day × 5 days every 28 days for 12 cycles. After 12 courses of chemotherapy MRI demonstrated complete regression of the pontine mass with an area of sequelae hemorrhage. The patient was followed up with complete radiologic response and no evidence of disease for three and a half years after completion of treatment, after which he relapsed and despite further treatment died due to progressive disease 6 years after diagnosis. There are a few reports in the literature indicating radiological complete response in DIPG. Although some imaging features such as extrapontine extension and greater craniocaudal dimensions are unfavorable prognostic factors, there is no defined radiologic response characteristic for prognosis in the literature. More studies are needed to predict a model for assessing the radiological response and prognosis.