P021 A case of radiation-induced haemorrhagic bullous lichen sclerosus of the breast

Abstract A 70-year-old lady presented with asymptomatic haemorrhagic bullae of her right breast 3 months after completing radiotherapy. Her right breast ductal carcinoma, diagnosed 9 months prior, was treated with surgery, adjuvant letrozole and radiotherapy. Her past history included type 1 diabetes, hypertension and ischaemic heart disease. She had no personal or family history of autoimmune conditions. Her breast surgery team performed initial biopsy to exclude cancer recurrence, which was nondiagnostic, and she was referred to dermatology. Two months later, she also developed perianal pruritus and pale plaques on other areas of her skin. On examination she had a large plaque of confluent haemorrhagic blisters on her right breast, with adjacent pallor and atrophy. Atrophic plaques with ‘cigarette wrinkling’ and peripheral hyperpigmentation were noted on her bilateral axillae, right thigh and left upper back. In addition, she had perianal pallor and superficial erosions. Breast biopsy confirmed features of bullous extragenital lichen sclerosus (EGLS) with hyperkeratosis, epidermal thinning and flattening, subepidermal bullae, homogenized dermal collagen and underlying lymphohistiocytic infiltrate. She responded well to ultrapotent topical steroids. Radiation-induced haemorrhagic bullous lichen sclerosus (RHBLS) of the breast is a rare complication of radiotherapy, typically presenting with painful haemorrhagic bullae and sclerotic skin changes. Unlike most radiotherapy-induced dermatoses, cutaneous involvement may extend beyond the irradiated field. Proposed mechanisms of pathophysiology include autoimmune, hormonal and genetic factors and trauma. Trauma-induced koebnerization is hypothesized to be a key mechanism in RHBLS, where radiation induces a T helper 2 immune response, characterized by upregulation of interleukin-4 and transforming growth factor-β, promoting fibroblast activity and sclerosis. In addition to dermoepidermal junction fragility in EGLS, radiotherapy-related lymphatic damage and friction of underwear may contribute to formation of bullae. There is no clear link between the radiation regimen and development of RHBLS. It may occur months to years after treatment. Management options include topical and systemic corticosteroids, phototherapy and methotrexate (Hobbs L, Tiwari N. Hemorrhagic bullous lichen sclerosus of the breast: a rare complication of radiotherapy. Cureus 2024; 16: e70194). Up to 90% of patients with breast cancer treated with radiotherapy develop cutaneous complications, underscoring the importance of recognizing radiation-induced skin conditions (Petersen E, Yazdani L, Hymes SR. A case of radiation-induced bullous morphea/lichen sclerosus overlap in a breast cancer patient. Rep Pract Oncol Radiother 2018; 23: 47–9). To the best of our knowledge, this is the fifth reported case of RHBLS. Early recognition is crucial to alleviate concerns about breast cancer recurrence and to rule out vulval lichen sclerosus.