General Surgery Coding Alert

Choose procedure code with pathology report in hand.

Integumentary procedures hold lots of snares for coders — from procedures codes to diagnosis codes to modifiers — and mistakes in these cases could cost your surgical practice significant pay.

Let our experts guide you through coding a single skin excision case to help you avoid the pitfalls and master some rules for the future.

Case: Patient presents with 0.8 cm x 1.0 cm forehead lesion described as “actinic keratosis” in the op report. The surgeon sharply divides the skin through the dermis to remove the lesion and 0.1 cm margins, followed by simple closure, and submits the tissue to pathology for examination. Two days later, the pathology report returns with a diagnosis of squamous cell carcinoma with positive margins. The patient returns two days after the pathology results, and the surgeon performs a second incision of 1.2 cm diameter with 0.1 cm margins with simple closure, resulting in clear margins, according to the final pathology report.

Pitfall 1: Biopsy Confusion

In this case, a significant error you might make is reporting the initial procedure as a skin biopsy instead of a skin excision. For instance, 11106 (Incisional biopsy of skin (eg, wedge) (including simple closure, when performed); single lesion) involves sharp removal of part of the lesion and simple closure of the site, similar to the op report description. The fact that the pathology report indicates that the surgeon did not remove the entire lesion (margins were not clear) might further lead you to wrongly choose a biopsy code.

Key: The important distinction between the skin biopsy codes and the skin excision codes is the surgeon’s intent to remove the entire lesion (excision) for both diagnosis and treatment, vs. intent to remove a portion of the lesion only for diagnosis. Ideally, the op report would memorialize the surgeon’s intent by labeling the procedure as an excision or a biopsy. Short of that, key terminology in the case descriptor (such as, the fact that the surgeon “removes” the lesion, including margins), should guide you to an excision code rather than a biopsy code. When in doubt, contact the surgeon to clarify documentation.

Cost: The pay difference between a biopsy or excision code in this case is significant. The Medicare Physician Fee Schedule (MPFS) national non-facility payment amount (conversion factor [CF] 34.8931) for 11106 is $162.95, while an excision code such as 11642 (Excision, malignant lesion including margins, face, ears, eyelids, nose, lips; excised diameter 1.1 to 2.0 cm) pays $277.40. That’s $114.45 you would leave on the table for improperly billing a biopsy code.

Avoid: Don’t ever report together a biopsy and an excision code for the same lesion at the same surgical session. CPT^® guidelines preceding the skin biopsy codes state that obtaining tissue for pathology during an integumentary procedure, such as excision, destruction, or shave removals, is a routine component of such procedures and not separately reportable. Per CPT^® guidelines, “The use of a biopsy procedure code (eg, 11102, 11103, 11104, 11105, 11106, 11107) indicates that the procedure to obtain tissue solely for diagnostic histopathologic examination was performed independently or was unrelated or distinct from other procedures/services provided at that time.”

Other missteps: Don’t be confused by another CPT^® code for premalignant lesions such as actinic keratoses (17000, Destruction (eg, laser surgery, electrosurgery, cryosurgery, chemosurgery, surgical curettement), premalignant lesions (eg, actinic keratoses); first lesion). Because the surgeon documents sharp excision including margins and closure, the excision codes are more appropriate for this case.

Pitfall 2: Coding Before Pathology Diagnosis

If you code the surgeon’s work based on the op report designation of actinic keratosis (L57.0, Actinic keratosis), you would select a code such as 11442 (Excision, other benign lesion including margins, except skin tag (unless listed elsewhere), face, ears, eyelids, nose, lips, mucous membrane; excised diameter 1.1 to 2.0 cm)

Correct: Because the pathology report diagnosed the lesion as squamous cell carcinoma, which is a malignant lesion, you should turn to code 11642 (Excision, malignant lesion including margins, face, ears, eyelids, nose, lips; excised diameter 1.1 to 2.0 cm) for the surgical procedure in this case.

“Always wait for the final diagnosis before coding surgical cases,” cautions Terri Brame Joy, MBA, CPC, COC, CGSC, CPC-I, billing specialty subject matter expert at Kareo in Irvine, Calif. Not doing so in this case would cost you $78.51 based on MPFS national non-facility amount (CF 34.8931) of $198.89 for 11442 and $277.40 for 11642.

ICD-10-CM: The appropriate diagnosis code for this case is C44.329 (Squamous cell carcinoma of skin of other parts of face). Because the anatomic location — the forehead — is a specific location, you should not use C44.320 (Squamous cell carcinoma of skin of unspecified parts of face). You should use C44.320 only “if your provider has not documented the precise location of the carcinoma on the patient’s face,” according to Chelle Johnson, CPMA, CPC, CPCO, CPPM, CEMC, AAPC Fellow, billing/credentialing/auditing/coding coordinator at County of Stanislaus Health Services Agency in Modesto, California.

Pitfall 3: Improper Lesion Measurement

Size matters when you’re billing the skin lesion excision codes, but if you don’t know what goes into the measurement, you’re likely to make another costly coding error. You should base the lesion measurement on “the excised diameter including margins, not just the diameter of the [lesion],” according to Kent Moore, senior strategist for physician payment at the American Academy of Family Physicians.

If you reported the malignant lesion excision based on the lesion size listed in the op report in this case, you might use 11641 (… 0.6 to 1.0 cm) instead of 11642. The pay you’d lose for that error is $31.40 (11641 pays $ 246.00 based on MPFS national non-facility amount, conversion factor 34.8931).

Do this: “Measure lesions for the CPT^® skin excision codes based on the longest measure of the excised lesion plus two times the widest margin documented,” Joy explains. In this case, that’s 1.0 cm + (2 x 0.1 cm) = 1.2 cm.

Pitfall 4: Missing Modifier

Based on the case report of “positive margins,” the surgeon did not successfully remove the entire squamous cell carcinoma lesion in the first operative session and performs a second excision four days after the initial excision.

The second excision is 1.2 cm plus 0.2 cm for margins for a total size of 1.4 cm. That means you should report the procedure as 11642.

Because the second procedure occurs within the 10-day global period of the first procedure, you should append modifier 58 (Staged or related procedure or service by the same physician or other qualified health care professional during the postoperative period) to the second procedure.

Avoid: Don’t use modifier 78 (Unplanned return to the operating/procedure room by the same physician or other qualified health care professional following initial procedure for a related procedure during the postoperative period.) in this case. Because the follow up excision is for the same condition that prompted the initial procedure (squamous cell carcinoma of that lesion), it is the second “stage” of the treatment, whether planned or not.

Cost: The surgeon should receive 100 percent of the allowable pay on both the first and the subsequent procedures when you use modifier 58, but not 78.