Dedifferentiated liposarcoma with an inflammatory malignant fibrous histiocytoma‐like component presenting a leukemoid reaction

A rare case of dedifferentiated llposarcoma (well‐differentiated llposarcoma with an inflammatory mallgnant fibrous histiocytoma (MFH)‐like anaplastlc component) occurrtng in a 69‐year‐old male is presented. The patient had noticed a dull pain in his left loin and thigh for about 1 month. Computed tomography examination revealed a low‐density mass lesion, measuring about 6 cm In diameter, in the left lliopsoas muscie, and It was surgically removed. Grossly, the lesion was composed of an encapsulated, soft, whitish mass and an adjacent, well‐demarcated, yellowish hard nodule, measuring about 2.5 cm In diameter. Microscopically, both lesions showed features of an inflammatory variant of MFH and a sclerosing type of well‐differentiated liposarcoma, respectively. To our knowledge, only two cases of dedifferentiated liposarcoma combined with inflammatory MFH as a dedifferentiated component have been recorded in the literature. The salient feature of the present case is a systemic inflammatory reaction, as shown by prominent leukocytosis (up to 73 900/mm 3 ) and the elevated serum value of C reactive protein (up to 26.0 mg/dL), which were transiently reduced after surgery. The Inflammatory reaction was suggested to be induced by cytokines, such as granulocyte colony‐stimulating factor and interleukin‐6, which were probably produced by the tumor cells in the present case, because the elevated serum values of those cytokines were decreased after surgery.