Skin Lesion Measuring Tips
CPT® provides different code sets to report excision of benign (11400-11471) and malignant (11600-11646) skin lesions/neoplasms. The codes within each set are differentiated broadly by site (for example, trunk and arms or legs vs. scalp, neck, hands, feet, and genitalia). Of prime importance are accurate lesion and margin measurements to allow for complete and appropriate coding.
CPT® instructions define the excised diameter of a lesion as the “greatest clinical diameter of the apparent lesion plus that margin required for complete excision.” Specifically, this is equal to the greatest size of the lesion, plus twice the size of the narrowest margin (the length of the incision used to remove the lesion is not a factor). Note that coding should be based on measurements documented prior to excision (rather than taken from the pathology report, for instance).
For example, the physician removed a lesion from the patient’s nose along the supra-alar crease. The lesion measures at 1.5 cm at its widest point and there was an allowance of 1.0 cm margin on all sides. The pathology report later confirmed that the lesion was benign.
To calculate, consider the narrowest margin (1.0 cm) x 2 = 2 cm. Add this figure to the widest measurement of the lesion (1.5 cm) for a 3.5 cm total. Based on the location of the lesion (nose) and the total measurement (3.5 cm), the correct code is 11444 Excision, other benign lesion including margins, except skin tag (unless listed elsewhere), face, ears, eyelids, nose, lips, mucous membrane; excised diameter 3.1 to 4.0 cm.
Note that CPT® codes are based on centimeters. Therefore, if the physician reports the diameter of the lesion in millimeters, you must convert the measurements (for instance, 1 mm = 0.1 cm). Please notice that some codes are reported in centimeters and others are in “square” centimeter measurements (0.16 sq in = 1 sq cm). You do not need to be a mathematician to perform conversions. There are many free online sites that offer automatic conversions when you enter the necessary information.
For example, if the physician has documented that he excised a benign lesion of the upper arm that is 5 mm in diameter (including margins), this would convert to 0.5 cm for CPT® coding accuracy and would be reported with 11400 Excision, benign lesion including margins, except skin tag (unless listed elsewhere), trunk, arms or legs; excised diameter 0.5 cm or less.