Malignant fibrous histiocytoma, MFH

Definition

The diagnosis of MFH was at one time extremely popular, constituting 40% of adult mesenchymal malignancies. However, it has now become clear that the morphological patterns seen in MFH are shared buy a range of poorly differentiated malignant neoplasms which can now be accurately subclassified. The latest WHO classification regards MFH as a synonym for pleomorphic sarcoma.

Histopathology

The tumour cells are pleomorphic. They may be large with copious cytoplasm, pale to eosinophilic, sometimes vacuolated. Cells may be oval or spindled, but not greatly elongated. Nuclei are bizarre, often multilobated. The nuclear membrane tends to be jagged.

Subtypes and their reclassification

Below are the subtypes of MFH as they were recognised and the current diagnostic entities that need to be considered.

Differential diagnosis

It is important to differentiate sarcomas from pleomorphic carcinomas, melanomas and lymphomas.

Tumours with a relatively good prognosis:

Benign tumours showing nuclear pleomorphism:

Prognosis

Pleomorphic sarcomas with myoid differentiation (pleomorphic leiomyosarcoma and pleomorphic rhabdomyosarcoma) are associated with a particularly poor prognosis.

References

1 Tos AP Classification of pleomorphic sarcomas: where are we now? Histopathology 2006; 48:51-62

2 Coindre JM, Hostein I, Maire G, et al. Inflammatory malignant fibrous histiocytomas and dedifferentiated liposarcomas: histological review, genomic profile, and MDM2 and CDK4 status favour a single entity. J Pathol 2004; 203:822-30

 

This page last revised 12.1.2008.

©SMUHT/PW Bishop