Pemphigus vulgaris following radiotherapy in head and neck cancer: Clinicopathological perspective of a rare cutaneous manifestation after radiotherapy treatment.

Pemphigus vulgaris triggered by the radiotherapy is rare and very few cases have been reported in the literature. Lesions within the radiotherapy field can be difficult to differentiate from post radiation dermatitis. Though exact pathogenesis is not understood, radiotherapy induced immunomodulation leading to bullous skin lesions, is thought to be critical. Here we present the clinicopathological perspective of pemphigus vulgaris involving the skin within and outside the radiotherapy portal, presented 2 weeks after the completion of radiotherapy. The condition requires multidisciplinary management and close coordination between oncologist, dermatologist, and dermatopathologist. Diagnosis is established based on the clinical presentation, histopathology, and direct immunofluorescence examination. Early institution of immunosuppressive therapy can improve the skin lesions and reduce the morbidity significantly.