Granular Cell Tumour

Epidemiology and Etiology:

• Schwann cell differentiation
• 30s-50s peak age
• Any age is possible

Common sites:

• Dermis
• Subcutis
• Larynx
• Bronchus
• Pituitary
• Stomach
• Bile duct
• Breast

Gross features:

• Small (<3-4cm usually)
• Poorly-circumscribed nodule
• 10-15% multifocal

Histologic features:

• Overlying squamous hyperplasia often
• Round to polygonal cells
• Abundant eosinophilic granular cytoplasm (lysosomes)
• Large nuclei
• Vesicular chromatin
• Small nucleoli
• Moderate nuclear pleomorphism maybe
• Collagen deposition may be prominent
• Spindled cells focally maybe
• No reliable features to distinguish benign vs. malignant (2%)
• Aggressive features (1-2 = atypical granular cell tumour, >2 = aggressive behavior)
• Necrosis
• Prominent nucleoli
• Mitoses >2/10HPF
• High N:C ratio
• Nuclear pleomorphism
• Spindling of tumour cells

Immunophenotype:

Marker:	Sensitivity:	Specificity:
PASD
S-100
NSE
Laminin
Myelin
CD68	Maybe
GFAP (neg)

Molecular features:

• 2% malignant

Other features:

References:

· Silverberg SG, DeLellis RA, Frable WJ, LiVolsi VA, Wick MR. Silverberg's Principles and Practice of Surgical Pathology and Cytopathology: 2-Volume Set. 4th ed. Churchill Livingstone; 2005.