Immunocompetent patient with isolated primary fourth ventricle lymphoma. Unusual diagnosis, their pitfalls, and challenges

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is an uncommon lesion and represent 4% of all central nervous system (CNS) cancers. There have been few reports of localized isolated lymphoma developing in the fourth ventricle, with only 8 previous cases described. We present a case of an immunocompetent patient with isolated fourth ventricle lymphoma who did not have diffusion-weighted imaging (DWI) restriction. CASE DESCRIPTION: A 45-year-old man presented a history of headache, vomiting and weigh loss. Upon clinical examination, he presented bilateral papilledema, multidirectional nystagmus, and gait imbalance. Magnetic resonance imaging showed a solid tumor in fourth ventricle with 1.8 × 1.6 × 1.1 cm. The patient was submitted to a suboccipital telovelar approach. The pathological study showed a neoplasm composed of loose round cells. Immunohistochemistry showed positivity for CD-45 and CD-23. The diagnosis of primary CNS lymphoma of the fourth ventricle was certified. Patient was sent to complementary treatment with hematologist and radiotherapy and chemotherapy were started. CONCLUSION: PCNSL is a rare and aggressive pathology with high rates of mortality and recurrence. It requires a multidisciplinary team and multiple therapies to control the disease and deliver better quality of life and prognosis to the patient.