Tumors developing in the posterior aspect of the brain are termed occipital lobe tumors. Both primary and secondary (metastatic) lesions were recognized in clinical practice and tumors of neural, skeletal, mesenchymal, and vascular origins have all been described. The principal symptom of an occipital lobe tumor is visual disturbance, with the severity depending on the extent of tumor spread. Headaches and seizures are additional complaints. The diagnosis rests on clinical criteria and a comprehensive imaging follow-up, mainly through computed tomography (CT) and gadolinium-enhanced magnetic resonance imaging (MRI).
Occipital lobe tumors encompass numerous neoplastic processes of different etiologies and clinical stages. The most important primary brain tumors that have been identified in the occipital lobe are tumors of neuroepithelial tissue (mainly gliomas, particularly low-grade), but vascular (such as hemangioendothelioma), mesenchymal (myxomas), and several other tumor types were also documented in the literature [1] [2] [3] [4]. Similarly to other brain tumors, headaches and seizures are common symptoms in this patient population [5] [6]. However, a suspicion toward an occipital lobe tumor can be made in the presence of visual disturbances [1] [5]. Visual hallucinations (that may or may not be accompanied by seizures) are some of the most frequent findings, presenting as light flashes consisting of different shapes, whereas prosopagnosia (inability to recognize previously known faces) is an important component of the clinical presentation [2]. Furthermore, patients with severe and expanding tumors that cause the destruction of one of the occipital lobes will suffer from homonymous hemianopia on the contralateral side [2]. When both lobes are affected, cortical blindness that is negated by patients (known as Anton syndrome) may be encountered [2]. In these cases, patients clearly state that they can see, despite a clinically confirmed absence of vision [2].
The diagnostic workup of patients in whom an occipital lobe tumor is suspected should start by conducting a thorough patient history, which will assess the onset of complaints, their progression, as well as severity. If patients report progressive visual symptoms (with or without headaches or epilepsy), a thorough examination of visual fields and acuity should be performed in order to assess the localization of the deficits. After sufficient clinical evidence has been gathered, imaging studies need to be employed; these are the gold standard for diagnosing brain tumors [1] [4]. MRI, using T1 and T2-weighted studies with gadolinium as a contrast, as well as fluid-attenuated inversion-recovery (FLAIR) sequence imaging, is considered to be the first-line study that allows identification of the exact location and the characteristics of the lesion [1] [3] [4] [6] [7]. When MRI is contraindicated (for example, in the presence of foreign metallic bodies or pacemakers), CT of the endocranium serves as an alternative [1] [4]. More advanced techniques are indicated when further diagnosis and treatment planning is required, such as functional MRIs (fMRI), MR proton spectroscopy, single photon emission tomography (SPECT), positron-emission tomography (PET), or visual evoked potential [6] [8] [9]. A definite classification of the tumor type is made from imaging findings and biopsy samples obtained either preoperatively or postoperatively [1] [4].