Leiomyomas are very common and show a fascicular arrangement of smooth muscle bundles. However there are a number of variants, atypical features, degenerative changes and treatment associated changes worth looking out for.
Cellular leiomyoma – Look much more blue, as the cells are closely packed with scanty cytoplasm with mitoses of upto 4-5/10hpf.
Epithelioid leiomyoma – More rounded cells
Symplastic/Atypical/Bizarre leiomyoma – Contains bizarre multinucleated tumor cells (moderate/severe atypia), less than 10 mitotic figures/10 HPF and NO tumor cell necrosis Associated with progestin use. Benign behavior, but rarely leiomyosarcomas may arise from them.
Uterine smooth muscle tumours of uncertain malignant potentional (STUMP): Grey area between cellular leiomyoma & leiomyosarcoma
Leiomyosarcoma – Nuclear atypia, Mitotic activity, Necrosis, Ill defined nodules.
Treatment with GnRH analogues – Give well demarcated areas of coagulative necrosis with a rim of inflammatory cells.
Treatment with selective arterial embolization – Transparent spheroids in the blood vessels
Degenerative changes – Hyaline change, Myxoid degeneration, Red degeneration (necrobiosis) esp in pregnancy – the cut surface appears red and homogenous. On micro ghosts of muscle cells remain.
Robboy’s Pathology of the Female Reproductive Tract.