Atypical Lipomatous Tumor
Spindle Cell Variant
Definition
- Atypical lipomatous tumor with predominant areas of bland spindle cells
Diagnostic Criteria for Spindle Cell Variant
- Mixture of patterns
- Predominantly bland spindle cells
- Short fascicles or whorls
- Indistinct pale cytoplasm
- Mild to moderate nuclear atypia
- Mitotic figures 1-2/hpf
- CD34 positive in two cases, extent not described
- Desmin rare cells positive
- S100, smooth muscle actin negative
- Areas of usual atypical lipomatous tumor seen in all cases
- Hypocellular or myxoid areas
- Rare: one series of 6 cases reported by Dei Tos 1994
- Ages 35-82 years
- 5 subcutaneous, I intramuscular
- Upper back, shoulder, upper extremity
- 3 with multiple recurrences, 1 dedifferentiated then metastasized
