Review of large deep lipomatous tumours.

BACKGROUND: Lipomatous tumours comprise a range of diagnoses. There are controversies regarding the histopathological diagnosis, nomenclature, diagnostic method, surgical management, roles of radiotherapy and the risk of metastasis, local recurrence and dedifferentiation. This study describes our experience with such tumours.
METHODS: Retrospective review of 224 soft tissue tumours from the Senior Author's (J. W. S.) database identified 28 patients with deep lipomatous tumours. Clinical features and outcomes were studied with median follow up of 1.5 years.
RESULTS: Eleven deep lipomas, six deep atypical lipomas, four well-differentiated (lipoma-like) liposarcomas, three well-differentiated liposarcomas and four liposarcomas were studied. Preoperative diagnosis was established by image-guided core biopsy in 20 patients, excisional biopsy in 6, incisional biopsy in 1 and fine-needle aspiration in 1. All patients diagnosed with deep lipoma and deep atypical lipoma underwent marginal excision. The median size of the excised tumour was 11 cm. Recurrence occurred in three deep atypical lipomas and one liposarcoma. Dedifferentiation occurred in one deep atypical lipoma, which transformed into a liposarcoma. None had metastasis or died of metastatic malignancy.
CONCLUSION: Large deep lipomatous tumours are uncommon and although they do not tend to metastasize, they not infrequently recur locally. Hence their local treatment to prevent local recurrence is important. Key aspects in achieving a complete, but marginal resection of the deep atypical lipoma and the well-differentiated lipoma-like liposarcoma is accurate preoperative diagnosis with core biopsy and accurate imaging to assess deep unsuspected extensions of the tumour.