Abstract
Radiation-induced hypopigmentation resembling vitiligo is rarely documented. The reverse Koebner phenomenon, where trauma causes the regression of existing lesions rather than the appearance of new ones, is even less common. We present a case of a 51-year-old female with vitiligo who experienced re-pigmentation following radiotherapy for tongue carcinoma.
Introduction
Vitiligo is characterized by well-defined, depigmented skin patches. Although its exact cause is unknown, it is believed to result from autoimmune-mediated melanocyte destruction and malfunction, leading to reduced melanin production in the skin and hair follicles.
The Koebner phenomenon describes the emergence of new lesions at trauma sites on previously unaffected skin in individuals with certain skin diseases such as psoriasis, vitiligo, and lichen planus. This trauma can be physical, chemical, thermal, allergic, or due to UV or ionizing radiation. Conversely, the reverse Koebner phenomenon, where existing lesions regress following trauma, is extremely rare. Only a few cases, particularly those involving radiation, have been reported. In 2013, a review found only four cases of radiation-induced reverse Koebnerization. Here, we describe a unique case of reverse Koebnerization in a 51-year-old vitiligo patient treated with radiotherapy for buccal mucosa carcinoma.
Case Presentation
A 51-year-old woman with generalized vitiligo was diagnosed with moderately differentiated squamous cell carcinoma of the left tongue border in July 2022. She underwent partial glossectomy and radical left neck dissection. Histopathology confirmed the carcinoma, staged as IVA.
Post-surgery, she received adjuvant chemoradiotherapy, following NCCN guidelines. This included weekly cisplatin (40mg/m2 for six cycles) and radiation therapy (66Gy to the oral cavity and 54Gy to the bilateral neck) using IMRT over nine weeks. She developed grade IV mucositis and grade II dermatitis, both of which resolved six weeks post-treatment.
Three months after radiotherapy, re-pigmentation began in the irradiated neck area. By six months, marked re-pigmentation had spread to her face and neck. A dermatologist confirmed the re-pigmentation and recommended continued use of hydrocortisone cream and sunblock. No additional treatment was advised, and she was scheduled for a six-month follow-up.
Discussion
Vitiligo, a chronic depigmentation disorder, results in white skin patches of varying sizes and locations. While its etiology is unclear, genetic, autoimmune, and environmental factors are implicated. The Koebner phenomenon, initially described in psoriasis, involves new lesion formation at trauma sites on previously unaffected skin. This can result from various types of trauma, including ionizing radiation.
The reverse Koebner phenomenon, or isomorphic nonreaction, involves the regression of existing lesions following trauma. Although rare, it has been observed in psoriasis patients treated with radiation. Few cases have documented this phenomenon in vitiligo patients. A 2013 review identified only 16 cases of reverse Koebnerization, with four attributed to radiation.
Previous cases include a 12-year-old girl with a drug-induced rash sparing the irradiated area post-Wilms tumor treatment, a 26-year-old woman with a similar phenomenon following liver irradiation, and a lung adenocarcinoma patient with steroid acne sparing the irradiated region. The exact mechanisms remain unclear, but interactions between the immune system, inflammatory responses, and wound healing are suspected. Potential factors include the loss of Langerhans cells, vascular alterations, and cytokine imbalances induced by radiation.
Further research is needed to understand the mechanisms and explore therapeutic implications for skin conditions influenced by this phenomenon.
Conclusions
The reverse Koebner phenomenon is an uncommon dermatological occurrence seen in patients with conditions like psoriasis and vitiligo, sometimes following radiation therapy. It involves the regression of existing lesions rather than the development of new ones. The underlying mechanisms are not well understood, necessitating further investigation. This phenomenon may involve cytokine imbalances or vascular factors affecting immune responses and lesion formation.
