Primary neoplasia
- Rare in domestic animals
- Rhabdomyoma
- Benign
- E.g. laryngeal in dogs
- Grossly:
- Lobulated with no capsule
- Histologically:
- Large granular cells
- Positive staining for myoglobin and desmin (immunoperoxidase technique)
- Z - band material can be seen by electron microscopy
- Rhabdomyosarcoma
- Malignant
- Mainly in dogs
- Metastases via lymphatics or venous routes -> in lymph nodes, lungs, spleen, heart and eleswhere in skeletal muscle
- Grossly:
- Pink masses with no capsule
- Histologically:
- Very varied
- Cells with or without visible cross striations
- Most easily seen with iron haematoxylin
- Muscle tissue only contains myoglobin detected by immunoperoxidase method
Metastatic neoplasia
- Can occur to skeletal muscle (e.g. carcinoma, haemangiosarcoma)
- Infiltrative lipomas of dogs
- Mature adipocyte tumours
- Usually deep in subcutis or muscle
- Infiltate along fascial planes or into muscles
- Grossly:
- Soft muscles
- Yellow fat separating fasciculi
- Histologically:
- Well-differentiated adipose cells