X04Exposure to ignition of highly flammable material

X04 is the ICD-10-CM diagnosis code for exposure to ignition of highly flammable material. It belongs to block X00-X08 (exposure to smoke, fire and flames) and chapter 20 (external causes of morbidity). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: X04.XXXA (initial encounter), X04.XXXD (subsequent encounter) and X04.XXXS (sequela).

The conditions in its Excludes2 note aren't part of X04, but may be coded alongside it if the patient has both: exposure to ignition or melting of nightwear (X05) and exposure to ignition or melting of other clothing and apparel (X06).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.