Multisystem inflammatory syndrome

This code represents a severe, often delayed, inflammatory response affecting multiple organ systems, typically occurring after an infection, most notably SARS-CoV-2. It is characterized by fever, inflammation, and evidence of organ dysfunction, mimicking conditions like Kawasaki disease or toxic shock syndrome.

Assign this code when documentation explicitly states "multisystem inflammatory syndrome" or "MIS," particularly in the context of a preceding infection. This diagnosis is supported by findings of systemic inflammation (e.g., elevated inflammatory markers) and involvement of two or more organ systems (e.g., cardiac, gastrointestinal, dermatologic, hematologic, neurological).

• Always code the underlying infection (e.g., COVID-19) first, if known and active, followed by this code.
• Do not confuse with simple sepsis or other specific inflammatory conditions; MIS is a distinct syndrome.
• Ensure documentation specifies "multisystem" involvement to differentiate from localized inflammatory responses.