["Dangerous" cutaneous polyp. Exophytic cutaneous myxofibrosarcoma].

Malignant skin tumors are seldom polypoid lesions. Thus lesions presenting as large skin tags, as in this case, may initially not be recognized and treated as a malignancy. Often such protuberant lesions are removed by shave biopsy. Then, as in this case, the clinician is very surprised to receive the diagnosis of myxofibrosarcoma (MFS). This case shows how important it is to further investigate a common tumor, like a large skin tag, when its clinical appearance is unusual. Myxofibrosarcoma or myxoid malignant fibrous histiocytoma is one of the common, perhaps most common, sarcoma in adults. Clinical presentation as a large skin tag is extremely uncommon. The rapid growth of the polypoid sarcoma indicates the need for completely operative removal. The behavior of the MFS depends on the degree of malignancy, depending on the tumor size, depth of penetration and local control. While smaller dermal or subcutaneous localized MFS hold potentially a risk of recurrence, do larger examples with a high tumor grade and seated in the deep soft tissue posses a variable metastatic potential. Despite large variability of cell number, cellular atypia and the numbers of mitotic figures all myxofibrosarcoma have in common the multinodular structure with incomplete septa, the mucinous stroma and curvilinear fine vessels.