Question: What diagnosis codes should I report for a patient with small cell carcinoma of unknown origin metastatic to the liver? Answer: You should report the small cell carcinoma of unknown origin with 199.1 (Malignant neoplasm without specification of site; other). -- The answers for You Be the Coder and Reader Questions were reviewed by Cindy C. Parman, CPC, CPC-H, RCC, co-owner of Coding Strategies Inc. in Powder Springs, Ga., and past-president of the American Academy of Professional Coders National Advisory Board.
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A note with 199.1 tells you that this code is appropriate for carcinoma of unspecified site, whether primary or secondary.
Then report 197.7 (Secondary malignant neoplasm of respiratory and digestive systems; liver, specified as secondary) for the metastasis to the liver.
Watch for: If the patient presents for treatment of the liver metastasis, 197.7 is the primary diagnosis and 199.1 is the secondary code. The official ICD-9-CM guidelines state that you should code the malignancy being treated as primary.