I don't think you'll find anything from the federal registry on this - that source never gets down to this level of detail on something that is not a widespread condition and/or not responsible for high volume expenditure, and I haven't even seen this level of specificity in the LCDs that address coverage of excision of skin lesions.
As for a diagnosis coding, the ICD-10 index clearly directs to coding this as a neoplasm of uncertain behavior. If the question concerns whether or not to code the excision as benign or malignant, there is guidance from CPT Assistant (May 2012) that "when the morphology of a lesion is ambiguous, choosing the correct CPT procedure related to the manner in which the lesion was approached rather than the final pathologic diagnosis since the CPT code should reflect the knowledge, skill, time and effort that the physician invested in the excision." So for this diagnosis, I would code accordingly based on whether the documentation reflects that the physician treated this as a malignancy and ensured that ample margins were cleared.
