Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 19 4 2020 08 25 452 455 Maryam Joudi Department of Immunology and Allergy, Allergy Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Mohammad Hosein Eshaghi Ghalibaf Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Atefeh Ghorbanzadeh Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Samira Zabihyan Department of Neurosurgery, Mashhad University of Medical Sciences, Mashhad, Iran Nasrin Moazzen Department of Pediatric Immunology and Allergy, Akbar Medical Center, Mashhad University of Medical Sciences, Mashhad, Iran Maryam Khoshkhui Department of Immunology and Allergy, Allergy Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 2019 02 12 2020 03 10 Brain tumors are the rarest cause of cerebrospinal fluid rhinorrhea. Non-traumatic cerebrospinal fluid rhinorrhea is also a relatively rare condition. It may be misdiagnosed as allergic rhinitis or chronic sinusitis and lead to unsuitable treatment. We described a 34-year-old man who came to our allergy clinic with a chief complaint of clear rhinorrhea from his left nostril with more than four years of duration. Onlyhypertrophy of left inferior concha was found in the clinical examination. His rhinorrhea aggravated when bending forward. So we were suspicious of CSF rhinorrhea. MRI was done for him and demonstrated a large tumor in the pineal region. The patient underwent surgery with resection of the mass via an infratentorial-supracerebellar approach. This case showed the role of maintaining differential diagnosis for a common complaint; rhinitis which is seen as usual. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/2308