EMC is a rare soft tissue neoplasm of the extremities that was first delineated as a distinct entity by Enzinger and colleagues.[1
] This rare entity is a slowly growing neoplasm with metastatic potential. The distinct cytological features that were seen in the present case include the presence of uniform cells with the morphology of immature chondroblasts set in an abundant stroma that is myxoid. As seen in chondrosarcomas, chondrocyte-like cells embedded within lacunae have been described in some case reports, but not in the present case. The arrangement of cells in cords and columns within a myxoid background is an important clue to diagnosis.[8
] If available, FISH analysis can also be performed on cytospin preparations to demonstrate the characteristic 22q12 translocation.[8
Other myxoid tumors of soft tissue that should be considered in the differential diagnoses on cytology include myxoid liposarcoma, soft tissue chondroma, myxoid variant of malignant fibrous histiocytoma, myxoma, and chondrosarcoma. Thus, fine needle aspiration cytology has proved to be a useful tool in the diagnosis of adult myxoid sarcomas.[10
Myxoid liposarcomas show characteristic lipoblasts with scalloped nuclei and vacuolated cytoplasm and a delicate, branching capillary network against a myxoid background. The myxoid variant of MFH displays marked pleomorphism of the nuclei with histiocyte-like cells. Chondrosarcomas typically possess a chondroid background and cartilage-like cells embedded within lacunae, rather than chondroblast-like cells lying loose within a myxoid stroma as seen in EMC.
Myxomas are sparsely cellular and show stellate cells within a translucent myxoid stroma. Chondroid lipoma is another rare soft tissue tumor that mimics EMC and myxoid liposarcoma.[11
] This tumor shows a mixture of mature lipocytes and lipoblast-like cells embedded in a chondromyxoid matrix. None of these tumors display the distinctive cytological features of the cells of EMC; this aids the pathologist in confidently making a diagnosis of EMC.
The diagnosis may be supported on histopathological investigation by the immunohistochemical profile of the tumor. Studies have shown that the tumor cells usually express vimentin, synaptophysin, S-100 protein, and epithelial membrane antigen.[12
] According to one of the studies which involved 23 cases, tumor size ≥ 10 cm, high cellularity, presence of anaplasia, and a mitotic activity of more than two per ten high power fields were all factors associated with decreased survival.[12
] Ploidy analysis showed the tumor to be diploid, aneuploid, or tetraploid. Ploidy status had no bearing on the prognosis in this study.[12
In conclusion, although histopathology confirms the diagnosis of EMC after excision, a preoperative diagnosis of EMC can be arrived at confidently due to its distinctive cytomorphological features.