Mesothelioma is a relatively rare tumor arising from the pleura, most notably associated with exposure to asbestos. Typically, mesothelioma is a locally aggressive tumor with a poor outcome in the order of months from the time of diagnosis. Although cases of distant metastases of mesothelioma have been documented in the literature, this tumor has less reported cases of metastases than other malignancies of the chest, and most reported cases of metastases have been identified in autopsy studies, likely related to the short survival times of patients harboring these tumors.

Intracranial schwannomas account for 8% of all primary brain tumors, approximately 80-90% of them being seen in the cerebellopontine angle in relation to the vestibular nerve. Schwannomas arising within brain parenchyma, unrelated to the cranial nerves, are extremely rare. To our knowledge, only 73 cases of intracerebral schwannoma have been described in the English-language literature so far,1-5 but only six cases of intracerebral schwannoma mimicking meningioma have been reported1-3 and there have been few reports regarding neuroradiological findings. Disagreement remains concerning the histogenesis of these tumors.

Rosette-forming glioneuronal tumor (RGNT) is a rare brain tumor found almost exclusively within the fourth ventricle. These grade I tumors were first included in the World Health Organization (WHO) Classification for the central nervous system in 20071. Since then, approximately 49 cases have been published.

There are no reported cases of RGNT within the third ventricle, although this tumor has also been described in the pineal region, the tectum and within the aqueduct. Supratentorial localization is quite rare, with only three published: one was found in the septum pellucidum, another within the optic nerve in neurofibromatosis type 1 (NF1) patient and one in a patient with multiple RGNT in the lateral ventricle. The authors report the first case series in the literature of RGNT occurring within the posterior third ventricle.

Dermal sinus tracts (DSTs) are an uncommon form of occult spinal dysraphism that is attributed to incomplete neural tube closure during fetal development. Dermal sinus tracts are found along the midline neuroaxis from the nasion to the coccyx, but they most commonly appear in the lumbar region. Dermal sinus tracts are more commonly associated with other developmental abnormalities such as skin tags, naevi, spinal dermoid cysts, meningocoele, lipomas and spinal cord tethering, and can be complicated by cerebrospinal fluid drainage, shedding of keratin from the epithelialized tract, and infection such as meningitis.