Internal Medicine Coding Alert

Internists trying to understand CPT 2003's changes regarding lesion removal can cut through the confusion by remembering one key point: You should measure the size of the lesion plus the margin you excise not the length of the incision you make to remove the lesion.

In 2003, CPT changed the 11400 series (Excision benign lesions) and the 11600 series (Excision malignant lesions). The new definitions specify that physicians should no longer code based just on the apparent size of the lesion removed but should also include the margin the normal-appearing tissue around the lesion that the internist excises to ensure complete removal of any biological extension of the tumor.

The illustrations showing lesions and their margins in the 2003 CPT manual (shown on page 49 of the professional edition, with the code numbers corrected in a later addendum) may be confusing to internists. One of the three illustrations shows, in addition to the lesion and the margin, the size of the incision in an elongated-football shape marked by long dashes (see illustration).

"I'm concerned that some doctors will look at that illustration and assume they can measure from the furthest point to the furthest point of the incision," says Kathy Pride, CPC, CCS-P, HIM applications specialist with QuadraMed based in San Rafael, Calif.

CPT included the drawing in the manual in an attempt to clear up such confusion, showing the difference between the margin and the incision area, says Allan Wirtzer, MD, a dermatologist in private practice at Mid-Valley Dermatology in Sherman Oaks, Calif., who helped develop the codes as the American Academy of Dermatology's representative to the CPT Advisory Committee.

"What they're trying to show in that illustration is that you don't use the size of the ellipse [or football-shaped incision area] to gauge what you're going to code," Wirtzer says.

Rather, you should use the size of the lesion (shown in shading at 2.0 centimeters) and the margin (shown in a solid oval of 0.2-cm margins on each side of the lesion) for a total size of 2.4 cm, he notes. The surgeon may make varying sizes of incisions depending on the type of lesion, its location and the closure method used, but its size should not affect code selection for the lesion, Wirtzer emphasizes. The physician generally makes an incision that is longer than the lesion because "the longer you make that ellipse, the flatter your scar is going to be," Wirtzer says.

The 2003 lesion-excision changes should benefit physicians because the new definitions recognize the varying amounts of time it can take to remove lesions of more aggressive biological types, Wirtzer says.

For example, when a patient presents with a basal cell carcinoma (which typically occurs in the outermost layer of the skin) measuring 1.0 cm, the surgeon may remove a 0.3-cm margin of normal-appearing tissue on both sides to ensure she removes the entire diseased area, leading to a total excised area of 1.6 cm. If the same 1.0-cm lesion appears to be melanoma (a more aggressive form of skin cancer), the physician will likely remove a larger area of normal-appearing tissue, perhaps 1 cm on each side, for a total excised area of 3.0 cm, Wirtzer says.

Both lesions in the example above clinically measure the same 1.0 cm and you would have coded them the same under 2002 rules, he notes. But in 2003, the excised area would be 1.6 cm (11602) for the basal cell carcinoma and 3.0 cm (11603) for the melanoma. By including the margin in the code, CPT recognizes the physician's extra effort when removing larger areas, Wirtzer says.

If the lesion and necessary margin is irregular in shape for example, long and narrow "you're allowed to use the longest diameter of the lesion in coding," Wirtzer says.

Payers expressed concern during the revision of these codes that physicians might abuse them, "trying to upcode by measuring larger and larger," Wirtzer says. He urges internists to use rulers to measure accurately the size of the lesion and its margin.

"You can't eyeball it," Wirtzer says.

Be sure to take excision measurements prior to removal, Pride advises. Remember that the pathology report will not give you an accurate measurement because lesions shrink when placed in formaldehyde, Pride says. She also reminds coders that even if physicians are certain that a lesion is benign or malignant, they should wait for the pathology report to code as benign or malignant.