Malignant peripheral nerve sheath tumour with annulate lamellae mimicking pleomorphic malignant fibrous histiocytoma.

The nature and nosologic status of malignant fibrous histiocytoma (MFH), or at least its most common pleomorphic variant, are a matter of controversy and it is possible that this entity represents the shared morphologic phenotype of a range of other dedifferentiated neoplasms. An unusual case of malignant peripheral nerve sheath tumour which very closely mimicked pleomorphic MFH is presented. Its true nature was only disclosed by ultrastructural examination. A further interesting and previously unreported feature in tumours of this type was the presence of annulate lamellae in many of the tumour cells. This case adds weight to the assertion that the light microscopic features of pleomorphic MFH may not be specific.