Undifferentiated Pleomorphic Sarcoma With Prominent Inflammation
Khin Thway, BSc, MBBS, FRCPath
Key Facts
Terminology
Pleomorphic undifferentiated malignant neoplasm with histiocytic and inflammatory cell infiltrate
Microscopic Pathology
Sheets of variably atypical xanthomatous cells
Prominent inflammatory cell infiltrate, particularly neutrophils
Admixed atypical cells with large nucleoli
May include Reed-Sternberg-like forms
Phagocytosis of cells
Can have focal storiform architecture
Ancillary Tests
Cytogenetic and molecular studies show that inflammatory MFHs share similar structural and genetic abnormalities to dedifferentiated liposarcoma
Suggests that most inflammatory MFHs are dedifferentiated liposarcomas
No other specific lines of differentiation identifiable
 Inflammatory malignant fibrous histiocytoma is shown with sheets of large cells with abundant foamy cytoplasm. The inflammatory background is apparent even at low power. |
 Inflammatory malignant fibrous histiocytoma contains a prominent infiltrate of neutrophils. Large atypical cells with vesicular nuclei and prominent nucleoli are also easily identifiable  . |
TERMINOLOGY
Abbreviations
Inflammatory malignant fibrous histiocytoma (MFH)
Synonyms
Undifferentiated pleomorphic sarcoma with prominent inflammation
Definitions
Pleomorphic undifferentiated malignant neoplasm with large, variably atypical xanthomatous cells admixed with atypical spindle cells and prominent acute and chronic inflammatory cell infiltrate
Although designated as specific subtype of MFH, many of these are now thought to represent dedifferentiated liposarcomas
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Etiology unknown for most cases
A few cases have occurred post radiation
CLINICAL ISSUES
Epidemiology
