[Hypopharyngeal sarcomatoid carcinoma with one time sarcomatous recurrence. A case report].

We report case of a patient with hypopharyngeal biphasic sarcomatoid carcinoma, with two tumor cell component, epidermoid and spindle cells, treated by surgery only. Two years later, recurrence is noted with totally different histologic form, sarcomatous monophasic, with spindle tumor cells and smooth muscle phenotype with immunohistochemistry, looking like primitive leiomyosarcoma of high malignancy degree. Such monophasic sarcomatous forms of sarcomatoid carcinoma, without epithelial tumor component, are deceptive and can be mistaken with primitive sarcoma. That is why discovery of epithelial differenciation signs, with immunohistochemistry or electronic microscopy, is very important. In our case, while the epithelial differenciation in the recurrent tumor is away, previous history of true biphasic sarcomatoid carcinoma in the same anatomic location, allows to assert recurrence of the same tumor with monophasic sarcomatous expression and smooth muscle phenotype in this case. Therefore in front of "sarcoma of the upper aerodigestive tract", of any immunohistochemical phenotype, monophasic sarcomatous form of epidermoid sarcomatoid carcinoma have always to be evocated and searched.