ICD-10: And so it started

Cracking the Code

Alexander Miller

Dr. Miller, who is in private practice in Yorba Linda, California, represents the American Academy of Dermatology on the AMA-CPT Advisory Committee.

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At the time of this writing the ICD-10 juggernaut has just started and, just as with Y2K, predictions of societal collapse did not materialize. Patients are still being treated, and bills for their treatment are still being produced. Sure, ICD-10 has many new codes, but they are not as daunting as feared, are they? As a consequence of a one-year delay from the original implementation date of ICD-10, providers, insurers, software developers, professional coders, office staff, the coding industry, and our American Academy of Dermatology (AAD) have wisely used the time reprieve to install functioning ICD-10 compliant billing and processing systems, to test the billing processes, and to provide us and our staffs with concise coding crutches. My office staff has been effectively supplementing and refining the ICD-10 code offerings prompted by my practice management program by integrating AAD resources such as the laminated ICD-9 to ICD-10 Crosswalk for Dermatology and the downloadable Dermatology ICD-10 CM Quick Coder, both available from the AAD website. Another helpful coding resource is available on the web at www.icd10Data.com, a free website offering ICD-10 code searches via conversion from ICD-9 and by medical diagnosis queries. Of course, having a hard copy of the actual ICD-10-CM manual is handy for traditional, paper data searches. When in a billing bind, you may pose questions to the ICD-10 Member to Member Community site, accessible from the AAD website. Your questions will be rapidly evaluated and answered.

The rich array of readily available ICD-10 coding resources should facilitate your finding the optimal descriptive code when faced with characterizing stupefying patient misfortunes such as being struck by a macaw (W61.12XA) while suffering burns streaking down the Amazon on burning water skis (V91.07XA). But what if the unfortunate victim was not focused upon recognizing the striking bird species at the time of impact but was certain that it was a parrot? Aha! W61.12XA (struck by other psittacines) describes just such a scenario. Notice that in this example each of the codes is composed of seven characters, ending with “XA.” The coding convention requires one to specify whether the encounter with the health professional is an initial encounter (XA), a subsequent encounter (XD), or represents a sequela to the injury (XS).[pagebreak]

The “ICD-10-CM Official Guidelines for Coding and Reporting,” expressed in the ICD-10-CM manual, provide general instructions for coding, including the following most pertinent to dermatology:

  • One should report diagnosis codes with the highest number of characters available
  • A specific diagnosis code may only be reported once per encounter
  • Laterality must be coded when left or right is specified in the code choices

A practical aspect of the above guidelines relates to multiple nevi. How does one code for nevi scattered throughout the integument, now that nevi have their own set of ICD-10 codes? Easy. There is no need to obsess about coding for every nevus seen. Realizing that the ICD-10 code D22.5 for nevi located on the trunk includes those on the chest including breasts, the back, the abdomen and the perianal skin, one would choose this one code to represent all of the nevi located in this anatomic zone. Then, assuming that there are other nevi documented on other areas, such as the extremities, scalp, or face, one would use individual site-specific ICD-10 codes to characterize those nevi. Code for nevi that you have identified in the patient record, but realize that there is no need whatsoever to code for every nevus seen in every anatomical area described in ICD-10. A representative listing of ICD-10 codes identifying select nevi will suffice. Below are more examples of potentially tricky ICD-10 situations.

Example 1: You schedule a California Medicare patient for an excision of an epidermal inclusion cyst located on the right upper eyelid. The cyst is depressing the eyelid and limiting the visual field. Your biller codes ICD-10 L72.0, epidermal inclusion cyst, and H53.481, generalized contraction of visual field, right eye.

Answer: Incorrect. The most appropriate code is ICD-10 H02.821, “cysts of right upper eyelid.” This code, when supported by the chart documentation indicating a visual field restriction, by itself would justify a covered service.

Example 2: A patient has multiple basal cell carcinomas on the right and left chest, shoulder, abdomen, and back. You destroy basal cell carcinomas located on the shoulder and the right chest. Your office bills the insurer the following ICD-10 codes: C44.611 for the shoulder basal cell carcinoma and C44.519 (basal cell carcinoma of other part of trunk).

Answer: Partially Correct. As the chart did not specify whether the carcinoma was located on the left or right shoulder, your biller correctly coded ICD-10 C44.611, “basal cell carcinoma of skin of unspecified upper limb, including shoulder.” The error in this case was with the charting, as reimbursement for the procedure could be jeopardized by the lack of laterality specificity: right shoulder (C44.612) or left shoulder (C44.619). Lesions on the trunk are not distinguished by separate laterality codes. [pagebreak]

Example 3: The same patient as in Example 2 returns for destruction treatment of left chest, right back, and abdomen basal cell carcinomas. Your biller discerns from the record that the left chest lesion is localized to the breast skin and bills the following ICD-10 codes: C44.511 (basal cell carcinoma of skin of breast) and C44.519 (basal cell carcinoma of other part of trunk) twice for the two remaining basal cell carcinomas.

Answer: Incorrect. The ICD-10-CM instructions direct that a specific diagnosis code may be reported once per encounter. Consequently, two identical diagnosis codes may be interpreted as duplicate billings by an insurer, leading to a payment denial for one of the procedures. In such a situation one may want to point out in the Notes section of the billing that two separate lesions were treated on distinct sites, and link this Note to the CPT malignant destruction codes for the trunk lesions. However, one should also be prepared to appeal a payment denial. Notice that the breast code has no laterality specificity (even though other structures that come in opposite sided pairs have left and right coding distinctions).

Example 4: You drain a painful abscess on a patient’s buttock. A bacterial culture grows methicillin sensitive Staphylococcus aureus. Your office bills the following ICD-10 codes: L02.31 (cutaneous abscess of buttock) and B95.61 (methicillin susceptible Staphylococcus aureus infections as the cause of diseases classified elsewhere).

Answer: Correct. The L00 L08 diagnostic code series, which includes impetigo, abscesses, cellulitis, and pyodermas, is preceded by the following ICD-10 instructional: “Use additional code (B95-B97) to identify infectious agent.” The practical corollary is that one should await a culture result, when done, in order to optimally code for such an encounter. If no culture is done, then one cannot precisely specify an infectious agent, and codes from the B95-B97 series cannot be used.

Example 5: A ruptured, abscessed epidermal inclusion cyst located on the back of a Medicare patient is incised and drained. The lesion is coded with ICD-10 L72.0 for the epidermal inclusion cyst and L02.212 for a “Cutaneous abscess of back [any part, except buttock].”

Answer: Correct. Both the cyst and the abscess ICD-10 codes should be specified, in that preferred order, for the incision and drainage procedure (CPT 10060, 10061) to qualify for Medicare payment consideration. As no bacterial culture was done, as it was not indicated, one should not list an infectious agent ICD-10 code from the B95-B97 series.

Example 6: You excise a right arm nevus suspicious for atypia and receive a pathology report specifying a junctional nevus with moderate to focally severe atypia. As the lesion is benign, your office bills ICD-10 code D22.61 (melanocytic nevi of right upper limb, including shoulder).

Answer: Indeterminate. Realizing that ICD-10 contains a code series expressly dedicated to melanocytic nevi, the biller selected an appropriate site-specific nevus diagnostic code. However, as the nevus is atypical, one cannot predict its future behavior from a single point in time biopsy evaluation. If left in place such a nevus could evolve the atypia to lesser or greater levels, including into a melanoma. Consequently, the future behavior of the nevus is uncertain, and an ICD-10 code D48.5, “neoplasm of uncertain behavior of skin,” would best describe the lesion. Code D48.5 is also appropriate for dysplastic nevi.