Severe Acute Radiation Dermatitis Following Ultra-Hypofractionated Whole Breast Radiation Therapy in a Patient With Systemic Lupus Erythematosus.

BACKGROUND: Whole-breast ultra-hypofractionated radiation therapy is an accepted adjuvant option for early-stage breast cancer, but evidence remains limited for patients with systemic lupus erythematosus (SLE), particularly those receiving chronic disease modifying antirheumatic drug (DMARD) therapy. CLINICAL SCENARIO: A 76-year-old woman with clinically quiescent SLE/Sjögren syndrome on mycophenolate mofetil was diagnosed with left breast invasive ductal carcinoma, ER/PR-positive and HER2-negative. After breast-conserving surgery and sentinel lymph node biopsy, pathology showed a 13-mm grade 3 tumor with lymphovascular invasion, negative margins, and 0/5 sentinel nodes, pT1cN0(sn), stage IA. Radiation omission was considered because of age, node-negative disease, and planned endocrine therapy; however, grade 3 histology, lymphovascular invasion, and Ki-67 of 43% placed her outside the lowest-risk populations supporting omission. During a period of active regional conflict with daily missile threats, an expedited regimen was selected. She received 26 Gy in 5 fractions to the left whole breast using supine field in-field 3-dimensional conformal radiation therapy, without regional nodal irradiation or tumor-bed boost. Dosimetry was acceptable, with PTV V95% 95%, maximum dose 104.9%, mean heart dose 0.8 Gy, and ipsilateral lung V8 Gy 15%. OUTCOME: Approximately 2 weeks after treatment, she developed progressive erythema, diffuse breast edema, pain, and extensive confluent moist desquamation beyond skin folds, without evidence of infection, consistent with RTOG grade 3 acute radiation dermatitis. Management included topical corticosteroids, silver sulfadiazine, enzyme alginogel, polymeric membrane dressings, analgesics, close nursing follow-up, and subsequent lymphedema-directed physiotherapy. Recovery was prolonged, and later rheumatologic reassessment documented recurrent systemic symptoms requiring belimumab. CONCLUSION: Although causality cannot be proven, the severity of acute dermatitis was atypical for FAST-Forward whole-breast irradiation and suggests that SLE-associated radiosensitivity may have contributed. Modern data indicate that connective tissue disease is not an absolute contraindication to breast radiation, and hypofractionation can be feasible. However, evidence is sparse for whole-breast ultra-hypofractionation in patients with SLE on chronic DMARD therapy. Multidisciplinary assessment, explicit counseling, consideration of moderate hypofractionation or reduced-volume treatment when oncologically acceptable, and systematic reporting of severe toxicity are warranted.