Anesthesia Coding Alert

Check out these best practices to help you locate the right code every time.

Due to its complexity, even expert coders find the ICD-10-CM Neoplasm Table confusing. Here are four FAQs to help you navigate these codes.

Understand When Primary Can Be Secondary and Vice-Versa

Question: Is it possible to code a secondary neoplasm as primary, or is a primary diagnosis always coded as such?

Answer: While it may sound confusing, from a coding perspective, sometimes a secondary neoplasm (where the cancer has spread to, or metastasized) can be coded as a primary (principal or first-listed) diagnosis, but you would still code the primary (principal or first-listed) diagnosis as a secondary cancer.

Here’s why: “If the treatment is directed at a malignancy, then that malignancy would be regarded as the principal [primary or first-listed] diagnosis. In other words, if the treatment is directed to a secondary malignancy, that is a principal diagnosis in this specific encounter,” according to Jill Young, CEMC, CPC, CEDC, CIMC, of Young Medical Consulting LLC in East Lansing, Michigan.

Example: A patient has colon cancer that has spread to the liver and is reporting to a clinician for treatment of the cancer that has now metastasized to the liver. In this example, the patient still has colon cancer, but the primary (principal or first-listed) diagnosis code for the encounter is metastatic, or secondary, liver cancer, not the colon cancer.

So, you would not code the colon cancer as C18.9 (Malignant neoplasm of colon, unspecified) first, as that is not what is being treated at this encounter; and neither would you code C22.8 (Malignant neoplasm of liver, primary, unspecified as to type) because the liver cancer being treated is not the primary cancer. You also should not report C78.5 (Secondary malignant neoplasm of large intestine and rectum) because the liver cancer was metastatic to the colon. Instead, as the treatment is directed to the liver, you will use C78.7 (Secondary malignant neoplasm of liver and intrahepatic bile duct) as the principal, or first-listed, diagnosis for this encounter.

Best practice 1: For metastatic cancers, always closely scrutinize your provider’s documentation. “If your provider notes the cancer is metastatic to, that means the cancer is secondary. If the note reads metastatic from, that means the cancer is primary,” Young notes (emphasis added). But for coding purposes, the principal, or first-listed, diagnosis will be the cancer to which the provider is directing treatment, whether that be a primary or metastatic cancer.

Understand This Difference Between In Situ and Other Neoplasms

Question: How do carcinomas in situ differ from benign neoplasms?

Answer: ICD-10-CM uses the same 1st character, D, for codes assigned to carcinomas in situ, benign, uncertain, and unspecified neoplasms. However, there is a world of difference between these conditions and their classification.

The National Cancer Institute defines carcinoma in situ, also known as “stage 0 disease,” as “a condition in which abnormal cells that look like cancer cells under a microscope are found only in the place where they first formed and haven’t spread to nearby tissue. At some point, these cells may become cancerous and spread into nearby normal tissue” (www.cancer.gov/publications/dictionaries/cancer-terms/def/carcinoma-in-situ).

In other words, you can think of in situ carcinomas as a group of cells that have the potential to become cancerous once they move to adjacent tissue, but they are not yet malignant and haven’t been diagnosed as benign.

Example: Your clinician diagnoses a patient with ductal carcinoma in situ (DCIS). The ICD-10-CM Table of Neoplasms does not direct you to a specific code for DCIS but to the D05.- (Carcinoma in situ of breast) category for all breast carcinomas in situ. To pinpoint the exact code, you’ll then go to the Tabular List, where you can verify the correct code for the location documented: D05.1- (Intraductal carcinoma in situ of breast).

Best practice 2: Locating the precise code for DCIS is a great reminder that you should never use the Table of Neoplasm in isolation. The absence of a precise code for DCIS in the table, or for any neoplasm for that matter, should drive you to the Alphabetic Index for precise identification of the condition and to the Tabular List for verification. ICD-10-CM general guidelines for Chapter 2 support this method of locating the correct code, while also specifically indicating the Alphabetic Index should be referenced first if the histological term is documented, as it will lead to the correct column in the Neoplasm Table.

Best practice 3: Make sure you read the provider notes carefully to verify that the diagnosis is, indeed, carcinoma in situ. A note that offers a diagnosis of DCIS with microinvasion, for example, indicates the condition has infiltrated the breast and is no longer in situ by definition. This would lead you to choose the appropriate code from C50.91- (Malignant neoplasm of breast of unspecified site, female) per the Alphabetic Index.

Understand This Difference Between Uncertain and Unspecified Neoplasms

Question: How do uncertain and unspecified neoplasms differ?

Answer: The columns for uncertain behavior and unspecified behavior in the Neoplasm Table can also be subject to misunderstanding. The two terms are not the same and are not interchangeable.

Use an unspecified behavior code when the medical record does not indicate the behavior of the neoplasm, or the behavior is currently unknown.

Example: If the clinician diagnoses a neoplasm of the cervix but provides no documentation that the neoplasm is malignant, in situ, benign or uncertain, or this information is currently pending pathology results, you would report unspecified code D49.59 (Neoplasm of unspecified behavior of other genitourinary organ).

Use an uncertain behavior code when a pathologist’s report specifically states that the histologic behavior of the cancer cannot be determined or predicted based on current testing.

Example: If the pathology report states the specimen’s behavior is uncertain, the Neoplasm Table directs you to assign a code such as D39.0 (Neoplasm of uncertain behavior of uterus). This would be because the pathologist cannot provide “histologic confirmation whether the neoplasm is malignant or benign,” per the note for the D37-D48 codes.

“It is a common mistake to utilize the uncertain behavior codes when a neoplasm is biopsied, and the results are currently unknown. It is important to remember that these codes are only reported when uncertain behavior is confirmed by pathology. You should only report an unspecified behavior diagnosis code when a biopsy is performed and pathology results are pending at the time of claim submission,” says Leah Fuller, CPC, COC, senior consultant at Pinnacle Enterprise Risk Consulting Services LLC in Charlotte, North Carolina.