Abstract
Introduction Intracranial germinoma is a rare but important differential in the work of up central nervous system (CNS) lesions.
Case An 18-year-old male presented with 3-month history of intermittent visual blurring and headaches. He had absent upward gaze. Fundoscopy showed focal optic disc oedema with phlebitis in the right eye. MRI brain revealed bilateral enhancing thalamic lesions with minor cystic change in the left thalamus. Cerebrospinal fluid (CSF) showed normal biochemistry, 27 white cells (96% lymphocytes). CFS anti-neuronal and limbic encephalitis antibodies were negative, oligoclonal bands were detected. HLAB51, ANCA were not detected and ACE level was normal.
Treatment involved 5-day course of 1g intravenous methylprednisone followed by tapering steroid dose with improvement in the ocular findings. PET scan and thoracic/mesenteric angiogram and testicular ultrasound were unremarkable. Three monthly progress MRI’s showed gradual increase in the size of the left thalamic lesion with worsening oedema and involvement of the left midbrain. Repeated CSF analysis showed leukocytosis with restricted oligoclonal bands and negative flow cytometry. Decision was made to proceed with biopsy of the left thalamic lesion. Histopathology demonstrated sheets of loosely cohesive cells with large nuclei and nulcleoli consistent with an intracranial germinoma. The patient was referred to oncology team for further treatment.
Conclusion This case highlights the presence of focal optic disc swelling as a primary presenting manifestation of intracranial germinoma. In addition, it demonstrates that intracranial germinoma can mimic CNS inflammatory lesions and that persistence of MRI changes should prompt consider of biopsy for tissue diagnosis.
