Polypoid fibroadipose tumors of the esophagus: 'giant fibrovascular polyp' or liposarcoma? A clinicopathological and molecular cytogenetic study of 13 cases.

Giant fibrovascular polyp of the esophagus is a descriptive diagnostic term intended to encompass rare, large, polypoid esophageal masses composed of fibroadipose tissue. Despite sometimes dramatic clinical presentations, they have historically been considered to represent reactive, non-neoplastic proliferations. Recently, however, a small number of reports have described well-differentiated liposarcomas of the esophagus, mimicking giant fibrovascular polyps. In order to clarify the relationship between esophageal liposarcoma and giant fibrovascular polyp, we retrieved esophageal cases coded as 'giant fibrovascular polyp,' 'lipoma' and 'liposarcoma' from our archives and re-examined their clinicopathologic features and MDM2 amplification status. Thirteen cases were identified (lipoma (n=1), giant fibrovascular polyp (n=5), well-differentiated liposarcoma (n=3), dedifferentiated liposarcoma (n=3)). The tumors ranged from 5.2 to 19.5 cm and arose predominantly in the cervical esophagus. All consisted chiefly of mature adipose tissue, with a variable component of fibrous septa. In all cases, close inspection of these fibrous septa showed them to contain an increased number of slightly enlarged spindled cells with irregular, hyperchromatic nuclei, similar to those seen in some well-differentiated liposarcomas. Three cases, all previously classified as dedifferentiated liposarcoma, showed in addition solid zones of non-lipogenic spindle cell sarcoma. By fluorescence in situ hybridization (FISH), all cases showed MDM2 amplification, confirming diagnoses as well-differentiated (N=10) and dedifferentiated (N=3) liposarcoma. Clinical follow-up (8 cases, range 22-156 months, median 33 months) showed 3 patients with local recurrences (1 well-differentiated and 2 dedifferentiated liposarcomas), 1 patient with liver metastases (dedifferentiated liposarcoma) and 2 deaths from disease (both dedifferentiated liposarcomas). These results suggest that the great majority of large, polypoid, fat-containing masses of the esophagus represent well and dedifferentiated liposarcoma, rather than 'giant fibrovascular polyps.' We suggest that the diagnosis of 'giant fibrovascular polyp' should be made with great caution in the esophagus, and only after careful morphological study and MDM2 FISH has excluded the possibility of liposarcoma.