In what scenarios (if ever) would you check peripheral blood flow cytometry in a patient with known multiple myeloma to evaluate for circulating plasma cells (CPCs) in the absence of an abnormal smear?

There are some retrospective data that CPCs are associated with worsened outcomes after transplantation. Anecdotally, CPCs could be collected as part of stem cell or T-cell collection. In the (rare) patient with symptoms suspicious for CNS involvement, perhaps CPCs would be helpful to know about before an LP. Would you ever check it?