Intramuscular Myxoma
Definition
- Generally hypocellular, hypovascular, bland pure myxoid lesion arising in skeletal muscle
Diagnostic Criteria
- Markedly hypocellular and hypovascular
- Abundant myxoid matrix
- Areas of increased cellularity and vascularity may be seen
- Must not involve >20% of a given tumor
- If >20%, designate as cellular myxoma
- No atypia, mitoses or necrosis even in cellular areas
- No difference in clinical behavior
- Must not involve >20% of a given tumor
- Involves skeletal muscle
- Grossly circumscribed, microscopically infiltrative
- Cytologically bland
- Small stellate or spindled cells
- No pleomorphism
- No atypia, mitoses or necrosis
- May have microcystic appearing acellular areas
- Muciphages may be present
- No lipoblasts
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: September 23, 2007