Oncology & Hematology Coding Alert

ICD-10-CM Coding:

Take 3 Steps to Be Certain With Uncertain/Unspecified Code Choices

Published on Tue Jan 24, 2023

Know why the distinction goes beyond the correct dx.

Of all the choices oncology coders have to make when assigning a diagnosis code to a patient’s suspected neoplasm, none is more difficult than knowing when to use an uncertain behavior or an unspecified behavior code. For example, suppose an area of a patient’s skin is excised and biopsied, and the results do not point conclusively to a malignant or benign neoplasm. Would you use D49.2 (Neoplasm of unspecified behavior of bone, soft tissue, and skin), or do you apply D48.5 (Neoplasm of uncertain behavior of skin)?

If you’re not sure because you are new to oncology ICD-10-CM coding, or if the distinction continues to confuse, here is a foolproof two-step method you can use, along with some example scenarios, to determine how to code these tricky diagnoses. And don’t forget to read the third step to find out why this distinction isn’t just important for accurate coding.

Step 1: Check the Guidelines for Unspecified

A good place to start is ICD-10-CM guideline I.A.9.b, which tells you “Codes titled ‘unspecified’ are for use when the information in the medical record is insufficient to assign a more specific code.” Or, to put it another way, “unspecified” indicates the provider did not reach a specific diagnosis. This is most likely because the procedure performed was a biopsy, which is the precursor to a pathology report, so the diagnosis at the time is still an unknown.

Example 1: The oncologist orders a biopsy of abnormal tissue on a patient’s arm prior to possible excision. Depending on the type of biopsy and number of lesions, you’ll choose from the following:

11102 (Tangential biopsy of skin (eg, shave, scoop, saucerize, curette); single lesion)
+11103 (… each separate/ additional lesion (List separately in addition to code for primary procedure))
11104 (Punch biopsy of skin (including simple closure, when performed); single lesion)
+11105 (… each separate/ additional lesion (List separately in addition to code for primary procedure))
11106 (Incisional biopsy of skin (eg, wedge) (including simple closure, when performed); single lesion)
+11107 (… each separate/additional lesion (List separately in addition to code for primary procedure))

For this scenario it would be appropriate for you to use D49.2. Payers typically allow coverage for this procedure, even with an unspecified diagnosis, since the procedure is done to determine the nature of the lesion. The oncologist will not know whether the tissue in question is benign or malignant at the time of the procedure as they are sending it to pathology to a confirm the diagnosis.

Step 2: Check the Note for Uncertain Synonyms

Unfortunately, there is no corresponding ICD-10-CM guideline telling you when you should use an uncertain behavior code. You will have to rely on your oncologist’s documentation to determine if you should use one.

“Assign uncertain codes when the pathologist cannot confirm the histologic confirmation. Words such as ‘dysplastic,’ ‘atypical,’ or ‘unusual’ in the pathology report mean there is supporting documentation the cells have been confirmed by a pathologist to have a specific characteristic that is not normal, but not confirmed to be malignant or benign,” says Kelly Loya, CPC, CHC, CRMA, CPhT, CHIAP, associate partner at Pinnacle Enterprise Risk Consulting Services, Charlotte, North Carolina. The physician may simply state pathology results are uncertain.

If you are unsure of the nature of the pathology cell type described, or the physician did not clearly document the interpretation for coding, query your oncologist to be sure they have assigned the correct code to the patient encounter. Incorrectly assigning the code could lead to improper reimbursement.

Example 2: Suppose your oncologist sends biopsied tissue to the pathology lab, and receives a report from the pathologist noting the original specimen may contain mutating cells that haven’t yet developed malignant characteristics. The pathologist recommends additional samples to see whether subsequent cells are progressing malignantly. Under these circumstances, if the lab performs a second biopsy, you would be justified in using D48.5 as the appropriate diagnosis code along with the relevant CPT^®biopsy code for the second biopsy encounter.

Alternatively, if the physician chose to excise the lesion completely to obtain the additional sample, D48.5 could support medical necessity for most payers since the initial pathology report concluded the initial specimen contained cells exhibiting uncertain behavior.

You won’t see this scenario often, because pathologists don’t often return uncertain behavior reports, says Mary I. Falbo, MBA, CPC, president of Millennium Healthcare Consulting in Landsdale, Pennsylvania. However, these codes are still useful, as “billing uncertain behavior avoids tagging the patient with a condition they don’t have,” according to Falbo.

Tip: You would use 11300-11313 for the shave technique and 11400-11446 for excising the lesion in the event the pathology report came back as benign or uncertain. You can only bill out 11600-11646 (Excision, malignant lesion including margins…) with a malignant diagnosis since the procedure includes wider margins, is more complex, and is higher risk due to a confirmed malignant condition.

Step 3: Know Why the Distinction Is Important

Many payers have policies that provide lists of covered diagnoses. Many of these medical necessity policies include codes from an uncertain category but not from the D49 unspecified category. “Do not be tempted to use a D49 code just to satisfy the coverage requirement for payment unless you have supporting documentation that the cell type is clearly identified as ‘uncertain,’” says Loya.