CPT Code 11900: Injection, Intralesional; Up to and Including 7 Lesions

What is an intralesional injection?

Intralesional injection refers to the administration of medication directly into abnormal skin lesions, rather than systemic administration. Commonly performed using a small gauge needle, the medication (typically corticosteroids) penetrates deep into lesions to maximize local therapeutic effects while minimizing systemic side effects.

Intralesional injections treat conditions such as keloids, cystic acne, psoriasis, granulomas, and hypertrophic scars, reducing inflammation, fibrosis, and lesion size.

CPT code 11900 documentation requirements

To support proper reimbursement and ensure compliance with coding practices, thorough documentation for CPT 11900 should include:

Diagnosis and number of lesions treated

Clearly specify diagnosis codes and indicate exactly how many lesions were treated during the same session.

Medication name, dose, and concentration

Document the specific medication directly injected, including name, dosage, concentration, and total amount administered.

Anatomical locations of injections

Precisely identify injection sites, noting each lesion's location and characteristics.

Clinical rationale and response to therapy

Include details on why intralesional injection was chosen, and document the patient's immediate or anticipated response to treatment.

CPT code 11900 billing guidelines

Accurate billing of CPT code 11900 requires following these essential guidelines:

Reporting based on number of lesions

Use CPT 11900 for up to and including seven lesions. For treatment involving more than seven lesions, report using the add-on code 11901, according to the code descriptor.

Exclusion for allergy testing or immunotherapy

CPT 11900 is not intended for allergy testing or immunotherapy; separate procedure codes should be used for these services.

Separate billing for medication

The injected medication must be billed separately using appropriate J-codes, such as J3301 for triamcinolone acetonide, per Medicare Administrative Contractors (MACs) guidelines.

Billing per session

Report CPT code 11900 once per patient care session, regardless of multiple procedures performed in the same session, unless specifically indicated otherwise.

Applicable modifiers for CPT code 11900

Modifiers clarify the details around intralesional injection procedures:

• Modifier 25: Indicates a significant, separately identifiable evaluation and management service provided by the same healthcare provider on the same day as the intralesional injection.
• Modifier 50: Used if intralesional injections are performed bilaterally (both sides of the body).
• Modifier 51: Report when multiple procedures, other than evaluation and management, are performed in the same session.
• Modifier 59: Signifies that the procedure was distinct or independent from other services performed on the same day.
• Modifiers LT and RT: Used to specify the injection location as either left side (LT) or right side (RT) of the body.
• Modifier 76: Modifier 76 indicates a repeat procedure by the same provider.
• Modifier 77: Modifier 77 indicates a repeat procedure by another provider on the same day.
• Modifier 78: Modifier 78 denotes an unplanned return to the procedure room by the same physician during the postoperative period for a related procedure.
• Modifier 79: Modifier 79 indicates an unrelated procedure performed during the postoperative period.

Other relevant CPT codes

Additional CPT codes relevant injection codes and similar procedures include:

• 11901 – Intralesional injection for more than seven lesions.
• 96405–96406 – Chemotherapy administration, intralesional.