Germinoma Mimicking Tumefactive Demyelinating Disease in Pediatric Patients.

Cases of intracranial germinoma with granulomatous reaction are rare, so a pathological diagnosis of this disease is difficult. In this report, we describe the case of a 13-year-old boy with a bilateral thalamic germinoma which initially mimicked tumefactive demyelinating disease with inflammation, based on the clinical symptoms, imaging results and histology of a biopsy specimen obtained endoscopically. Upon examination of the cerebrospinal fluid, oligoclonal bands were detected. Although his symptoms and radiological findings improved following steroid pulse treatment, they worsened dramatically almost 1 year after the first surgery and even after an additional steroid pulse treatment. Prompted by the clinical course, a second biopsy was performed, and a pathological examination of the specimen showed a two-cell pattern. The diagnosis was changed to intracranial germinoma. After chemotherapeutic treatment with etoposide and cisplatin, the patient's symptoms and radiological findings dramatically improved. We conclude that it is very challenging to distinguish germinomas with a granulomatous reaction due to other inflammatory diseases, especially when only small specimens can be obtained. Stereotactic or endoscopic biopsies should be performed using samples from several different points even if the lesions are associated with eloquent brain regions.