First if it is documented as a cyst then that is what must be coded. Second the diagnosis is the patient's not the providers, so when you assign a
diagnosis code to a claim then the payer takes that as information about the patient and they can use that to assign risk and for benefit assignment. The coder must be the one that assigns the code based on the provider rendered diagnostic statement not based on the provider's chosen code.
The answer you want may be as simple as the code book.. in the code book under the section heading for neoplasm of uncertain behavior it states:
Categories D37-D44, D48 classify by site neoplasms of uncertain behavior, i.e., histologic confirmation whether the neoplasm is malignant or benign cannot be made. ( histologic confirmation is a path report or any report where a pathologist has rendered a diagnosis after viewing the submitted sample under a microscope, for instance it could be a cytology report)
Category D49 classifies by site neoplasms of unspecified morphology and behavior. The term 'mass', unless otherwise stated, is not to be regarded as a neoplastic growth.
** many years ago the AHA coding clinics indicated that in this context the word "mass" is used loosely to indicate any abnormality that has yet to have further refinement by a diagnostic measure such as an ultrasound, so if the provider states skin lesion or abnormality of skin then you would use L98.9. **
In the guidelines it states that code assignment is based on the providers diagnostic statement that a condition exists.
This is not the same as a code choice.
Take the example of the patient where the provider rendered the diagnosis of Charcots Joints in the ankles in a patient with type II diabetes. The code chosen by the provider was A52.16 Charcôt's arthropathy (tabetic), and that is the code the coders used on the claim and the one they submitted on the patients request for disability. However that is not the code for the diagnosis the provider rendered. The office claims that is the correct code because it is the one the provider chose.. So what's the problem??? A52.16 is a code for a disease of late syphilis and not a diabetic complication. The term tabetic means it is due to syphilis and the category A52 is for late syphilis. The point being these were all AAPC certified codes in this office and not one of them thought to actually look the code up and change the code for the claim. the end result is the disability has been denied and now they are all being taken to court because the patient is suing them.
I use this example to point out that you code the correct code based on the rendered diagnosis not based on the providers code assignment.