Hint: Code to location, not to etiology. Few of us knew about Kaposi sarcoma (KS) until the acquired immunodeficiency syndrome (AIDS)/human immunodeficiency virus (HIV) epidemic of the mid-1980s. At that point, KS became synonymous with AIDS/HIV patients, though that population was not the only one affected by the condition, which causes tumors or lesions to appear on the skin, mucous surfaces, and other body areas. Since that time, the prevalence of the condition has diminished as new drugs and treatment have reduced AIDS/HIV levels considerably among the U.S. population. Even so, KS still remains a cancer that has the potential to confuse oncology coders. So, we’ve rounded up a few of your pressing questions about the condition and assembled the answers in this FAQ. What Is KS? KS “is a cancer that develops from the cells that line lymph or blood vessels. It usually appears as tumors on the skin or on mucosal surfaces such as inside the mouth, but these tumors can also develop in other parts of the body, such as in the lymph nodes …, the lungs, or digestive tract,” according to the American Cancer Society (www.cancer.org/cancer/kaposi-sarcoma/about/what-is-kaposi-sarcoma.html). The American Cancer Society identifies four different kinds of KS, “defined by the different populations it develops in” as follows: How Are the Different Types of KS Coded? KS, along with other opportunistic infections, develops once an individual’s immune system is compromised. As this etiology is the same in all populations, ICD-10-CM does not distinguish between the four types of KS. Instead, like most cancers, you can determine the ICD-10-CM code for KS based on its anatomic location: What Is the Correct Code to Use for KS of the Lymph Nodes? This sounds like an easy coding question to answer: Kaposi’s sarcoma of lymph nodes is coded to C46.3. However, complicating this is the inclusion term “Kaposi’s sarcoma of lymphatic(s) NEC [Not elsewhere classified],” which appears below C46.1. The difference between the two terms is that “lymphatics” refers to the entire lymphatic system, while “lymph nodes” refers to the small filters located throughout the body that remove unwanted material from the lymph fluid that flows throughout the system. So, for KS in the lymph nodes only, you’ll use C46.3; for KS in the entire lymphatic system, you’ll use C46.1; and for KS in the system and the nodes, you can use both codes as the Excludes 2 note for C46.1 suggests. “Unlike Excludes 1 notes, which identify conditions that cannot occur simultaneously, Excludes 2 notes indicate that the condition is represented by a different code and can be reported at the same time as the code under which it appears,” says Leah Fuller, CPC, COC, senior consultant at Pinnacle Enterprise Risk Consulting Services, Charlotte, North Carolina. How Do I Apply the Code First Instruction Under the C46 Block? Again, this also seems like an easy coding question to answer. The instruction for any of the C46.- codes tells you to “code first any human immunodeficiency virus [HIV] disease” with B20 (Human immunodeficiency virus [HIV] disease). However, the code first instruction only applies if the primary reason for the service, such as a skin biopsy, is for the KS that has manifested due to AIDS. In this case, you should code B20 first in the diagnosis coding sequence, followed by the appropriate KS code. The instruction does not apply for patients with classic (Mediterranean), endemic (African), or iatrogenic (transplant-related) KS. Remember: if the oncologist is treating the patient for a condition other than KS, and the patient has AIDS, you would need to follow the appropriate sequencing for that condition. In such cases, “if ICD-10-CM does not specify a sequence among the codes in question, then you should align the diagnosis codes with the reasons for the visit. In this case, you should code the HIV status (B20) second,” says Kent Moore, senior strategist for physician payment at the American Academy of Family Physicians.