Myxoid and Round
Represents 30-35% of all liposarcomas.
Myxoid and round cell liposarcomas commonly occur in the limbs
usually between third and fifth decade.
Purely myxoid liposarcoma
(low grade tumour)
is characterised by hypocellular bland spindle cells in a myxoid
Univacuolated lipoblasts are noted around the vessels.
Multivacuolated lipoblasts are present in the peripheral subcapsular
There are thin walled
arranged in a plexiform
pattern ('crow's feet' or 'chicken wire
Mitotic figures are
Myxoid/round cell liposarcoma
is characterised by hypercellular areas with undifferentiated round
These cells are larger with hyperchromatic and more rounded
configuration, in contrast to the spindle cells in the myxoid variant
. Mitotic figures are more frequent.
These tumours have an aggressive behaviour.
Transition to hypercellular (round cell) areas are noted in myxoid
Pure round cell
is rare (more than 80% round cells).
More than 10%
round cell areas - increased potential for metastasis.
More than 25%
round cell areas - High grade tumour.
Myxoid Tumours of Soft Tissue
Differential diagnosis: Intramuscular
Myxofibrosarcoma (myxoid MFH),
extraskeletal chondrosarcoma, myxolipoma, well differentiated liposarcoma.
Round cell liposarcoma -
diagnosis: Metastatic carcinoma, lymphoma, melanoma,
Undifferentiated round cells and bland spindle cells in myxoid and
round cells display cytoplasmic and nuclear positivity with S100 protein.
lipoblasts stain positively with S100 protein.
Plexiform vascular areas may be demonstrated by CD31
Cytogenetics- t(12;16) (q13;p11) with rearrangement of the CHOP gene.