ALK-negative CNS anaplastic large cell lymphoma: case report and review of literature

Background Central nervous system (CNS) lymphomas frequently pose a diagnostic challenge to physicians. CNS anaplastic large cell lymphoma (ALCL) is a rare condition. A majority (80%) of ALCLs harbour anaplastic lymphoma kinase 1 (ALK-1) mutation with only a minority testing negative for this mutation. Methods Here we report a rare case of ALK-negative CNS ALCL with dural involvement. We conducted a literature search using PubMed for published studies in English on cases of patients with ALCL of the brain. The keywords used were 'anaplastic large cell lymphoma', 'ALK' and 'primary central nervous system lymphoma'. Results A 63-year-old man presents with waxing and waning cranial nerve and spinal cord symptoms. MRI revealed multiple intracranial and intra-spinal lesions that were highly steroid responsive. A wide range of serum and CSF tests were non-diagnostic during three months of workup before a lesion appeared in the cervical spine that required decompression and allowed us to obtain a tissue sample. Final pathology revealed ALK-negative ALCL. There are only 24 reported adult cases to date of CNS ALCL in the English literature. To our knowledge, this is the first case of ALK-negative ALCL with primarily CNS and meningeal involvement. Conclusions ALK-negative ALCL with CNS involvement is extremely rare, which frequently results in delayed diagnosis (average 40.5 days). The diagnostic challenge posed by this case highlights the importance of a team approach to workup and diligent patient follow-up for such a rare disease.