Lipoblastoma-like tumour of the vulva: Report of three cases of a distinctive mesenchymal neoplasm of adipocytic differentiation

Aims: We sought to delineate and describe three cases of a distinctive mesenchymal neoplasm of the vulva showing adipocytic differentiation and affecting young patients. Methods and results: In three patients between 13 and 38 years of age, the vulvar tumours had well-circumscribed borders and ranged in size from 35 to 100 mm. Histologically, they were well circumscribed and lobulated. The lobules were separated by thin fibroconnective tissue septa and were composed of slender spindle cells showing slightly eosinophilic cytoplasm with indistinct boundaries, uniform nuclei with finely granular chromatin, and no nucleoli. The cells were embedded in a richly myxoid stroma. The background in all three tumours was a 'chicken-wire', capillary vascular network resembling that seen in myxoid liposarcomas. Two tumours had scattered signet-ring-type lipoblasts and the third a large number of such lipoblasts. Clusters of mature adipocytes were entrapped in the tumours. None had mitotic figures, necrosis, or pleomorphism. The neoplastic cells stained positively for vimentin and were negative for other immunohistochemical markers. Treatment for all three tumours was enucleation alone. After follow-up of 10 years, 7 years, and 1 year, all patients are well with no evidence of disease. Conclusions: The benign behaviour of these neoplasms militates against the diagnosis of liposarcoma. We believe these are benign lesions of adipocytic differentiation akin to infantile lipoblastomas.