Subacute (active) lichen planus

This code represents a form of lichen planus characterized by an ongoing, active inflammatory process that is not acute but also not chronic. It involves purplish, polygonal, pruritic papules and plaques affecting the skin, mucous membranes, hair, or nails, with a duration typically longer than acute but less than chronic presentations.

Assign this code when documentation specifies lichen planus as "subacute" or "active" without explicitly stating acute or chronic. This diagnosis is supported by clinical notes describing the characteristic lesions and their ongoing, non-acute nature.

• Differentiate from acute (L43.0) and chronic (L43.2) forms based on the physician's specific documentation of disease duration and activity.
• Ensure the documentation clearly indicates "subacute" or "active" to justify this specific code.
• Consider additional codes for specific sites of involvement (e.g., oral, genital) if documented and a more specific code is not available.