Ossifying fibromyxoid tumor (OFMT) of soft parts is rare soft tissue tumor that can show a spectrum of behaviors. Folpe and Weiss listed criteria for recognizing an OFMT that may require more aggressive management.
Outcomes:
(1) distant metastases
(2) local recurrence
Parameters:
(1) nuclear grade
(2) cellularity
(3) mitotic rate per 50 high power field (hpf)
(4) infiltrative growth pattern
Nuclear Grade
Cellularity
Mitotic Rate
Behavior
low
low
< 2 per 50 hpf
typical
high
NA
>= 2 per 50 hpf
malignant
NA
high
>= 2 per 50 hpf
malignant
high
NA
< 2 per 50 hpf
atypical
NA
high
< 2 per 50 hpf
atypical
low
low
>= 2 per 50 hpf
atypical
where:
• A simple score can be created from mitotic rate per 50 hpf AND from (nuclear grade OR cellularity being high).
Distant metastases occurred in 4-6% of typical and atypical tumors and 60% of malignant tumors.
Local recurrence was associated with:
(1) malignant tumors
(2) infiltrative growth pattern
(3) positive or close surgical excision margins
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