Figure 1: In lungs, lymphangiomyomatosis shows proliferation of plump spindle-shaped myoid cells that are arranged in short fascicles around arterioles, venules, and lymphatics which causes thickening of alveolar septa. The spindle cell proliferation can range from subtle and easily overlooked to overt tumor-like nodules. The tumor cells may invade lymphatics and blood vessels causing secondary hemorrhage and destruction of the septal wall. This image shows focal aggregates of spindle cells in the walls of cystically-dilated airspaces.
Figure 2: High magnification view showing proliferation of plump spindle-shaped myoid cells arranged in short fascicles causing thickening of the alveolar septal wall. The spindle cells have uniform nuclei and lack cytologic atypia. Mitotic activity is not increased.