ICD-10 Code L13.9 – Bullous disorder, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L13.9 – Bullous disorder, unspecified
What it is
L13.9 is used for a bullous skin disorder when the record does not identify a more specific type. It indicates blistering disease, but the exact cause or subtype is not documented.
Clinical signs
Typical findings include tense or flaccid blisters on the skin, sometimes with erosion after rupture. Clinical features vary; refer to documentation for the specific pattern, distribution, or associated mucosal involvement.
When to use this code
Use L13.9 when the clinician documents a bullous disorder or blistering condition without naming a specific diagnosis. It is appropriate when the chart supports a blistering disease but does not distinguish pemphigoid, pemphigus, or another defined entity. Check documentation if the subtype is unclear.
Do not use for
Do not use this code when the record identifies a more specific bullous disorder, such as a named autoimmune blistering disease. Do not use it for simple trauma-related blisters or other non-bullous skin lesions.
Coding tip
Query the provider when “bullous” is documented but the exact disorder is missing, because a more specific code may be available.