Leptomeningeal myelomatosis in previously treated high-risk kappa light chain multiple myeloma: case report and literature review

Maro Ohanian1, James Alaly2, Stephen Samuel3, Christian Cable1, Kathleen Halka11Department of Hematology/Oncology, 2Department of Radiology, 3Department of Hematopathology, Scott and White Healthcare, The Texas A&M Health Science Center College of Medicine, Temple, Texas, USAObjective: To describe leptomeningeal myelomatosis (LM) in previously treated high-risk kappa light chain multiple myeloma (MM) and to review the literature.Case report: A 71-year-old female with previously treated kappa light chain myeloma presented with right lumbosacral discomfort. Magnetic resonance imaging (MRI) of spine revealed multiple intradural masses involving the cauda equina, with mass effect on adjacent nerve roots. Brain MRI was unremarkable. Cerebrospinal fluid flow cytometry confirmed an abnormal population of plasma cells with kappa restriction; CD38, CD138, and CD56 were positive. She was originally diagnosed with kappa light chain myeloma 10 months earlier while hospitalized for anemia, thrombocytopenia, renal failure, and hypercalcemia. Bone marrow revealed plasma cell myeloma approaching 100% cellularity, with 92% plasma cells, atypical plasmacytoid cells with prominent nucleoli, and significant cytogenetic abnormalities: deleted 13, c-myc rearrangements, -X, +1. Treatments consisted of seven cycles of bortezomib with weekly dexamethasone. Her last dose had been 4 months earlier. After treatment, bone marrow demonstrated a complete remission with normal cytogenetics. Her clinical course had otherwise been indolent with a good hematologic response. After diagnosis of LM, therapy included focal external beam radiation to the cauda equina, weekly bortezomib and dexamethasone, intrathecal (IT) cytarabine liposomal every 2 weeks for five doses, and monthly IT cytarabine liposomal thereafter. The cerebrospinal fluid gradually cleared on serial lumbar punctures and follow-up MRI demonstrated near complete resolution of the intradural masses. Five months after diagnosis the patient is essentially asymptomatic.Conclusion: The incidence of central nervous system (CNS) involvement in MM patients is 1%. LM is associated with cytogenetic abnormalities and plasmablastic morphology. It can occur with a seemingly low tumor burden. Novel agents such as bortezomib allow for prolonged survival in high-risk patients; however, with inadequate CNS penetration, complications such as LM may be inevitable.Keywords: leptomeningeal myelomatosis, intrathecal, complete remissio