Post-Radiation Scleroderma: Body Distribution
Post-radiation scleroderma (localized morphea) presents primarily within the radiation field itself, but can extend beyond the irradiated area and may even affect distant previously irradiated sites. This is a critical distinction from typical radiation dermatitis, which remains confined to the treatment portal.
Primary Presentation Sites
The condition develops most commonly at the specific anatomical site that received radiation therapy:
- Breast tissue following breast-conserving therapy and radiation for breast cancer, where approximately 48-55% of patients with systemic sclerosis develop skin thickening in the radiation port 1, 2
- Head and neck region following radiation for head and neck cancers, with 69% developing local radiation-induced skin thickening 1
- Abdominal wall following pelvic radiation for gynecologic malignancies 3
Critical Clinical Pattern: Extension Beyond Radiation Ports
A distinguishing and concerning feature is that post-radiation scleroderma can extend beyond the original radiation field:
- Fibrosis may extend outside the irradiation portals and result in damage to underlying viscera 4
- Skin reactions can appear at distant sites that were previously irradiated, even when new radiation is delivered to a completely different anatomical location 3
- One case demonstrated scleroderma developing in the breast after radiation, with subsequent similar reactions appearing in the previously irradiated abdominal wall and both lower extremities when breast radiation was administered years later 3
Timing and Recognition
This condition typically manifests as a late effect, approximately 1 year after completion of radiation therapy 5:
- The delayed onset distinguishes it from acute radiation dermatitis, which occurs during or immediately after treatment 6
- Progressive fibrosis develops over months following radiation exposure 3
Important Clinical Caveat
The diagnosis requires biopsy confirmation, as the clinical presentation mimics cancer recurrence and radiogenic subcutaneous fibrosis 5. The main differential diagnoses include recurrence of carcinoma and standard radiation-induced fibrosis, making histopathologic confirmation essential before attributing skin changes to post-radiation scleroderma 5.