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Question: A patient had a lab come back showing elevated light chains. The oncologist indicated there was no evidence of malignancy or a plasma cell dyscrasia on a test of the bone marrow. The coder had the primary diagnosis of C90.00, but I believe this is incorrect. Instead, I believe it should be R88.8. Who is right?

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Answer: While elevated light chains can be an indicator of multiple myeloma, unless the provider has documented a definitive diagnosis of a malignancy, your coder cannot assign any code from C90.- (Multiple myeloma and malignant plasma cell neoplasms), much less C90.00 (Multiple myeloma not having achieved remission) with any degree of certainty in this case.

Instead, as the provider has indicated there is no malignancy, a signs and symptoms code may be your best bet in this situation. Since there is no ICD-10-CM code directly correlated with elevated light chains, and no mention of the specific lab test performed, R88.8 (Abnormal findings in other body fluids and substances) may be your best option. However, this is definitely a situation where you will need to query your oncologist before assigning any code to correspond with the test results.

Bruce Pegg, BA, MA, CPC, CFPC, Managing Editor, AAPC