From the Q&A section:

Question:

I have a patient with a large (~15 cm) soft tissue mass in his flank which on initial evaluation is consistent with a large lipoma (95% sure, but I've been tricked with sarcomas before). For the excision, would I use the skin code (11406) or the musculoskeletal code for excision of soft tissue tumor of flank (21930). The work I will have to do matches the 21930 code better, but I don't know what the coding guidelines are for lipomas.

Answer: 

According to CPT® Assistant August 2006 if a lipoma is excised from a superficial location it would be appropriate to use excision codes from the integumentary system (e.g. 11400-etc). If the lipoma is in deep subcutaneous, subfascial or submuscular tissue use code from musculoskeletal system (e.g. 21930).

Clarification:

Lets say its neither superficial nor subfascial...its just a big ugly deep lipoma in an obese patient. Big excision, I'll have to leave a drain. The excision of soft tissue of flank (21930) doesn't say anything about subfascial or intramuscular

Answer:

A lipoma is a fatty tumor, and you would excise it from the soft tissue of the flank. There is nothing in the descriptor of 21930 that would obviously preclude its use in your situation, but consider the 10 day global for the 11406 vs 90 days for code 21930. It depends on extent of work involved.