ATYPICAL LIPOMA

Publisher Website
Google Scholar
Abstract
The designation atypical lipoma has been suggested for a grup of well-differentiated non-metastasizing [human] liposarcomas characterized by only moderate nuclear atypia. New cases (21) of atypical lipoma are described. The tumors were mainly composed of univacuolated fat cells without cellular or nuclear atypia, but also showed univacuolated fat cells with enlarged, moderately polymorphic, dark nuclei. In 2 of the tumors a few multivacuolated fat cells with scalloped nuclei were found. Small multinucleated cells with overlapping, peripherally arranged nuclei, reminiscent of so-called floret-like cell as in pleomorphic lipoma, could occasionally been seen. Areas of generally delicate linear or patchy fibrosis with atypical nuclei were a common finding. Two atypical lipomas were studied ultrastructurally. The ultrastructural findings suggest that the nuclear polymorphism is of a neoplastic nature rather than of a regressive change. Nine atypical lipomas were located intramuscularly, 2 intermuscularly and 10 s.c. Five of the subcutaneous tumors and 3 of the inter- and intramuscular tumors recurred 1 or more times. Most of them, particularly the subcutaneous ones, had primarily been diagnosed as ordinary lipomas, but re-examination of the histological sections after 1 or more recurrence revealed overlooked nuclear atypia. Metastasis or dedifferentiation at recurrence was not seen in any case.