Absence of enhancement in a lesion does not preclude primary central nervous system T-cell lymphoma: A case report

BACKGROUND Primary central nervous system lymphoma (PCNSL) is a non-Hodgkin lymphoma that originates in the central nervous system (CNS) and is exclusively limited to the CNS. Although most PCNSLs are diffuse large B-cell lymphomas, primary CNS T-cell lymphomas (PCNSTLs) are rare. PCNSTLs typically demonstrate some degree of enhancement on contrast-enhanced magnetic resonance imaging (MRI). To the best of our knowledge, non-enhancing PCNSTL has not been reported previously. CASE SUMMARY A 69-year-old male presented to the neurology department with complaints of mild cognitive impairment and gradual onset of left lower leg weakness over a span of two weeks. Initial MRI showed asymmetric T2-hyperintense lesions within the brain. No enhancement was observed on the contrast-enhanced T1 image. The initial diagnosis was neuro-Behcet's disease. Despite high-dose steroid therapy, no alterations in the lesions were identified on initial MRI. The patient's symptoms deteriorated further. An MRI performed one month after the initial scan revealed an increased lesion extent. Subsequently, brain biopsy confirmed the diagnosis of PCNSTL. The patient underwent definitive combined chemo-radiotherapy. However, the patient developed bacteremia and died of septic shock approximately three months after diagnosis. CONCLUSION The absence of enhancement in the lesion did not rule out PCNSTL. A biopsy approach is advisable for pathological confirmation.