Unusual subcutaneous mixed tumour exhibiting adipose, fibroblastic, and epithelial components

A subcutaneous mass in the left supraclavicular fossa of a 55-year-old woman proved on histological examination to be composed of islands of squamous cells embedded in bands of spindle cells and associated with mature adipose tissue. Electron microscopy showed that the spindle cells were fibroblastic in nature and not squamous cells showing spindle differentiation. There was also a minor lymphangiomatous component and sparse infiltrates of lymphoid cells. The lesion bore certain similarities to thymolipoma except that the presence of spindle cells and the site were atypical. While it may be speculated that the tumour was thymolipoma occurring in an ectopic cervical thymus the lesion is provisionally regarded as an unusual mixed tumour featuring mesenchymal and epithelial components.