How would you approach a patient with solitary plasmacytoma with an FLC ratio >100, but a negative bone marrow biopsy and negative PET-CT?

Are we to assume the Ca, Hgb, and creatinine are normal? Completing the testing with 24 hr UPEP with immunofixation is important. With a free light chain ratio of >100, there is generally proteinuria. If 24 hr urine total protein is 1 g/day or more, I would do a kidney biopsy to document light chain...

Multiple myeloma is a patchy disease. It would explain the negative bone marrow biopsy.