Myolipoma of the eyelid

Background: This report describes the pathology of a myolipoma which occurred in the eyelid. Myolipoma is a benign hamartomatous tumour in which smooth muscle cells are interspersed with adipocytes. Patient details: an irregular yellowish tumour (30x25 mm) with ill-defined borders had been present for 50 years in the medial part of the left lower eyelid of a 67-year-old woman. The tumour was excised and studied by conventional histology, immunohistochemistry and transmission electron microscopy. Results: The tumour was formed by bundles of spindle-shaped cells with cigar-shaped nuclei intermingled with multiloculated clear cells containing small eccentric nuclei. By immunohistochemistry, positive staining of the spindle cells was restricted to smooth muscle actin and desmin; the clear cells were non-reactive with the immunohistochemical panel, but fat was identified within the cytoplasm. The ultrastructural features of the spindle cells were those of a leiomyoma, while the clear cells were classified as adipocytes. Conclusion: This tumour was considered to originate from the media of blood vessels within the tumour.