SPINDLE-CELL AND PLEOMORPHIC LIPOMA - AN ULTRASTRUCTURAL-STUDY

Spindle cell and pleomorphic lipoma are rare benign tumors of adipose tissue. Their histogenesis is poorly understood and pleomorphic lipoma has not previously been studied ultrastructurally. This study describ es the morphology and ultrastructure of 6 cases of spindle cell and pl eomorphic lipoma. Both spindle cell and pleomorphic lipomas showed sim ilar ultrastructural features with an interrupted basal lamina, occasi onal non-membrane-bound lipid vacuoles and abundant rER. In all the ca ses mast cells were conspicuous and were intimately related to both sp indle and pleomorphic cells. It is proposed that both the spindle and pleomorphic multinucleated cells that characterize these tumors are pr elipoblastic mesenchymal cells. The possible significance of an intera ction between these cells and mast cells is discussed.