A case of radiation induced osteosarcoma of the skull presenting as a cutaneous epidermotropic tumour with a short latent period

Abstract

Radiation induced sarcoma is an unusual but well documented tumor. The frequency of radiation induced sarcoma of the head and neck region has been reported as 0.143%. In the literature the median interval between irradiation and development of sarcoma is 11 years. Cases of RIS with a short latent period i.e. less than four years are rare. We report a case of a 34 year-old female who developed an osteosarcoma of the scalp, over a previous craniotomy scar, three years after excision of a frontal anaplastic oligodendroglioma which had been followed by a course of 6 weeks radiotherapy (58 Gy) and 6 cycles of Temozolomide. The histological features were those of a high-grade osteosarcoma with epidermotropism of tumor cells. Lymph nodes were partially replaced by high-grade metastatic osteosarcoma with extra-nodal lymphatic tumor thrombi. To our knowledge the only other case report of post-radiation osteosarcoma with a short latency period was a case of osteosarcoma in the craniofacial bone three years after radiotherapy for maxillary squamous cell carcinoma. The histological finding of prominent replacement of the epidermis by osteosarcoma has not been reported before.