Pediatric Coding Alert

Question: Our provider saw an established 6-year-old patient who had been scratching a mosquito bite for several days. The patient presents with a slight fever and a red, blistered area on the back of their right hand. Pus is seen coming out from the infected bite. The provider diagnosed the patient with cellulitis caused by a staph-infected mosquito bite. Which ICD-10 code do I report for this encounter?

Virginia Subscriber

Answer: This encounter requires you report more than one code, actually. Let’s start with the cellulitis.

To find the correct cellulitis code, start with the ICD-10 Alphabetic Index. You’ll see that coding depends on the area of the body. In this case, the entry for cellulitis of the hand directs you to “cellulitis, upper limb,” which in this case will code to L03.113 (Cellulitis of right upper limb).

When you look at the instructions for the L00-L08 code range in ICD-10, you’ll see the Use additional code note that instructs you to also include a code to identify the infection agent. The medical notes mention staphylococcus as the infectious agent, but they don’t specify in greater detail. This means you’ll need to include B95.8 (Unspecified staphylococcus as the cause of diseases classified elsewhere) with the claim also.

You’ll also need to consider the presence of the mosquito bite that started it all. For a nonvenomous insect bite, you’ll use W57.XXX- (Bitten or stung by nonvenomous insect and other nonvenomous arthropods), remembering to add a 7th character, per the code’s instructions. This means adding one of the following: A [Initial encounter], D [Subsequent encounter], or S [Sequela] to accurately record the stage of healing. As the patient is actively receiving treatment, you will report W57.XXXA.