Plasma cell disorders are a group of diseases in which plasma cells proliferate excessively and produce large amounts of abnormal antibodies. Plasma cell diseases are categorized as malignant or of undetermined nature. Malignant plasma cell diseases include multiple myeloma, etc., and those of undetermined causes include monoclonal immunoglobulinemia, etc. Clinical manifestations of multiple myeloma include osteoporosis, bone pain, anemia, vomiting, malaise, rhinorrhea, and renal impairment. Monoclonal immunoglobulinemia of undetermined cause, the etiology of which is still unclear, has no obvious clinical symptoms and occasionally causes pins and needles and numbness due to nerve damage. Multiple myeloma requires chemotherapy and, in severe cases, stem cell transplantation. Monoclonal immunoglobulinemia of undetermined cause usually does not require treatment and regular review is sufficient. Patients with plasma cell disorders should go to the hematology department of a hospital and follow the doctor’s instructions for symptomatic treatment to avoid delays.