Yujie Zhang¹, Fatemeh Fekrmandi², Jingxin Qiu^3,

Primary central nervous system (CNS) lymphoma represents approximately 4% of CNS tumors, among which majority are originated from B-cells and only 2% from T-cells. Anaplastic large cell lymphoma (ALCL), a subtype of T-cell lymphoma, is classified into anaplastic lymphoma kinase (ALK)-positive and -negative subtypes. While the former accounts for 70-80% of cases, ALK-negative ALCL represents only a minority of cases. Here we present a case of primary CNS ALK-negative ALCL in a 73-year-old black male. He initially presented with significant fatigue and was treated for malaria with minimal improvement. He was subsequently found to have leukocytosis and developed left-sided weakness and facial droop. MRI showed a large temporoparietal intra-axial mass with vasogenic edema and mass effect. Initial brain biopsy was non-diagnostic. He was placed on steroids and pursued further workup in our institution. Upon tapering steroid, he developed left leg weakness. Repeat MRI revealed multiple intracranial lesions with one showing progression after steroid tapering. Repeat biopsy was performed and a diagnosis of primary CNS ALK-negative ALCL was rendered 47 days after the initial nondiagnostic biopsy. Literature review showed 39 reported cases of primary CNS ALCL, among which only 11 cases were ALK-negative. We present this case to demonstrate; a. the non- specific clinical presentation poses a diagnostic challenge. b. multiple intracranial lesions, along with waxing and waning clinical course with steroid administration, could be a sign of CNS lymphoma and c. biopsy prior to start of steroids is preferred for diagnosis.