Granular cell tumor
Figure 1. The basic Schwann cell nature of this lesion is indicated by the numerous cell processes, which are fairly uniform in width and have a tendency to be aligned in a parallel fashion. The focal extracellular zones contain multiple layers of basal lamina (arrows). Within the cytoplasm of the cell processes are secondary lysosomes and small lipid droplets. X11,200.

Figure 2. In another portion of this granular cell tumor (myoblastoma), the density of secondary lysosomes, some quite large (arrow), accounts for the cytoplasmic granularity reflected in the terminology for this lesion. The material within the lysosomes consists of vesicular structures containing varying amounts of variably, but often darkly, staining cellular debris and likely lipid-rich lamellar structures (arrowheads), often within a background of moderately densely staining granular substance. X13,300.

Figure 3. Another example of a granular cell tumor. The micrograph shows a compact aggregate of the variably sized processes of tumor cells each containing innumerable secondary lysosomes. X3,500.

Granular cell tumor