Sebaceous carcinoma (SC) is a malignant adnexal tumor, usually originating from eyelids. Extra-orbital sebaceous carcinoma is a rare carcinoma localized commonly in head and neck region. Although extra-orbital SC has an indolent course, it may have highly invasive properties and may cause distant metastases rapidly. We report a 46 year-old-woman with extra-orbital SC originating from lumbar skin. Just after two months from the excision of primary lesion, patient readmitted with axillary lymphadenopathies. positron emission tomography (PET-CT) was used for evaluation of both extent of disease and treatment response. Partial remission was observed with docetaxel treatment. This case illustrates how extra-ocular SC can behave aggressively despite the traditional belief. PET-CT can help to evaluate the extent of disease and response to therapy.