Other hypereosinophilic syndrome

This code represents a rare group of disorders characterized by persistent and unexplained overproduction of eosinophils in the blood and/or tissues, leading to organ damage. It encompasses forms of hypereosinophilic syndrome (HES) that do not fit the criteria for myeloproliferative HES or lymphocytic HES. The clinical presentation is highly variable, depending on the organs affected.

Use this code for patients diagnosed with a form of HES that is not specifically classified as myeloproliferative (e.g., FIP1L1-PDGFRA fusion gene positive) or lymphocytic. Documentation should clearly state "other hypereosinophilic syndrome" or describe HES features without evidence of a specific genetic mutation or T-cell clonality. This code is appropriate when the underlying cause of eosinophilia is unknown or not otherwise specified as a distinct HES subtype.

• Ensure documentation explicitly rules out myeloproliferative (e.g., D47.Z1) and lymphocytic (D72.111) forms of HES before assigning this code.
• Always sequence this code as the primary diagnosis when HES is the reason for the encounter and treatment.
• Code any associated organ manifestations (e.g., cardiomyopathy, neuropathy) separately as secondary diagnoses.