The Tumor is a Granular Cell Tumor

Here, tumor infiltrates bronchial glands. Tumor cells are round to spindled. Some have multiple nuclei. There is little stroma.

Special Studies for Granular Cell Tumors

PAS-D Stain

The cytoplasmic granules of these tumors stain red with the PAS stain after diastase digestion (PAS-D stain) as shown here. This stain is not specific for these tumors.

 

S-100 stain

The immunohistochemical stain for a neural protein, S-100, gives a positive reaction with the tumor cells. This reaction is part of the evidence that the tumor cells show Schwann cell differentiation.

Electron Micrograph--Low Power

Electron microscopy of these tumors shows that the cytoplasm is packed with rounded digestive vacuoles (secondary lysosomes) filled with cellular debris. Some granules are electron dense and others are lucent.

Note the nucleus at the left edge of the cell.

Photo provided by Dr. Ben Yen

Electron Micrograph--High Power

At higher magnification, the variety of inclusions in the membrane-bound lysosomes is more apparent.

Electron microscopy was not performed in this case.

Photo provided by Dr. Ben Yen

 

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