Morphea (also known as localized scleroderma) is characterized by abnormal activity of fibroblasts and deposition of thickened collagen. Radiation induced morphea (RIM) is a rare complication of radiation treatment. Clinically, patients may present with pain, discoloration, and disfiguration of the affected area. There is no correlation with radiation dose, fractionation, boost, age, or presence of other dermatological or connective tissue disorders. It is thought that radiation induced cytokines may induce activation of fibroblasts leading to fibrosis. There is an increase in myofibroblast population in irradiated skin, but RIM is different from post-irradiation fibrosis, which is a common side-effect and occurs within the first three months.

RIM can be divided into 2 phases: the inflammatory phase shows perivascular and periadnexal lymphocytes; and the sclerotizing phase with fibrotic retraction and pigmentation. Although not fully developed, this biopsy reveals features suspicious for morphea (inflammatory phase with early sclerotic changes), which may be seen in RIM.

The biopsy shows neither prominent tissue edema nor evidence of malignancy; nor is there thickening of the basement membrane. Within the dermis there is a moderately dense superficial and deep perivascular, periadnexal - and notably interstitial - lymphohistiocytic infiltrate with numerous admixed plasma cells. There is no significant neutrophilic, eosinophilic or granulomatous inflammation and no lymphoid atypia is present. There is subtle sclerotic change with swelling of collagen bundles, prominent chronic inflammation of the subcutaneous tissue (septal and lobular) with some mild fat necrosis.

Differential diagnoses include chronic radiation dermatitis, cancer recurrence, new carcinoma, cellulitis, and recall dermatitis. Common treatment ranges include: topical, systemic steroids, calcineurin inhibitors, systemic immunosuppressant drugs, phototherapy, antibiotics, and imiquimod. However, there is no clear regimen and results are often unsatisfactory.

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1) Spalek, M., et al. J Eur Acad Dermatol Venereol. 2015 Feb;29(2):197-202