In multiple myeloma does the absence of osseous lesions mean anything?

Yes it does: Smoldering myeloma or mgus can produce high levels of m- protein but that does not require treatment. If there no bone lesions, you do not meet the criteria for myeloma yet, so active treatment for myeloma is not indicated unless you have bone lesions or other signs and symptoms of myeloma, (often called 'crab' criteria for instituting treatment.).