# HELP--Calculating excision margins



## renifejn (Nov 18, 2010)

Excision of nevus with intermediate closure

"The lesion measuring 42x21mm was excised in a 65x24mm elipse"

I know I have to convert this to cm, but can someone take me through how I should be calcuating this?

Thanks so much


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## preserene (Nov 18, 2010)

Let me try! There is no mention of benign or malignant
it seems the lesion is 4.21x 2.1 cms. The lesion excised is 6. 5x 2.5.
The greatest diameter of the lesion is 4.21 cms
The      ''             "       "     excised  is 6.5 cm-  that seems to be inclusive of the two margins which is solely by the decision of the surgeon( he is eligible to do so).
 So it is the total(greatest) diameter of the excised lesion of that particular anotomical site and that particular type of lesion - Benign or malignant.
 You assign the code accordingly


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## renifejn (Nov 19, 2010)

Thanks-so just to clarify (sorry I'm a bit confused)


You are saying the greatest diameter is 6.5?


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## FTessaBartels (Nov 19, 2010)

*Not quite*

It is incumbent upon the physician to state the size of the lesion including MINIMAL margin necessary. CPT uses the phrase: lesion diameter plus the *most narrow *margins required equlas the excised diameter. (emphasis added by FTB) The size of the incision may be considerably larger than this. 

For an example, look at CPT 2010, professional edition, page 60, (my book comes direct from the AMA), top of page, first drawing.  The actual lesion is 2.0 x 1.0 cm. The margin is 0.2 cm. So the total lesion size is 2.4 cm (represented by the blue ellipse. HOWEVER, the incision is the MUCH longer ellipse (approx 6 cm) drawn with black dotted lines. 

Our surgeons MUST dictate the minimal margin necessary for complete removal of the lesion. If they do NOT dictate this, then only the lesion measurement itself is used to determine its size. 

The size of the incision is separately reported so that we can accurately code for the layered or complex closure. 

In this specific example, it won't make any difference to your coding because any lesion over 4.0 cm is coded the same. But it is important to help train your physicians on how to report the lesion sizes vs the incision/repair length. 

Hope that helps.

F Tessa Bartels, CPC, CEMC


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