ICD-10-CM
ICD-10 code for Cyst (colloid) (mucous) (simple) (retention) peritoneum: K66.8
The ICD-10-CM index points "Cyst (colloid) (mucous) (simple) (retention) peritoneum" to K66.8, Other specified disorders of peritoneum. K66.8 is a billable code.
Source: CDC ICD-10-CM FY2027 Alphabetic Index file dated June 16, 2026. Publisher page
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