Mesenchymal tumor markers: special proteins and enzymes

Pathologic classification of soft tissue sarcomas

A number of immunological markers and chromosomal abnormalities are described to aid in the diagnosis, prognosis and management of soft tissue sarcomas. Although the chromosomal abnormalities may be specific in some cases, they have only been reported in small series or single cases and their significance has not yet been established. None of the immunological markers described is either entirely specific or sensitive for a particular tumor type, and virtually none of these immunological reagents is currently approved for diagnostic use despite their widespread applications in pathology. They function in a supporting role to conventional tissue pathology, grading, and pathological and clinical staging of soft tissue sarcomas. Antibodies employed as an aid in diagnosis of soft tissue tumors should always be run in panels and never as single tests. New immunological markers and chromosomal abnormalities in soft tissue sarcomas should be carefully evaluated for their specificity and sensitivity and their usefulness in diagnosis and prognosis.

Experimental rhabdomyosarcoma with regions like malignant fibrous histiocytoma (MFH)--a true double phenotypic pattern?

In murine sarcomas induced by 20-methylcholanthrene, histological features of malignant fibrous histiocytoma (MFH) as well as rhabdomyosarcoma were found in the same tumour both at light microscopy and at ultrastructural level. The areas showing rhabdomyomatous differentiation expressed vimentin, desmin, muscle-specific alpha-actinin, and sometimes myoglobin, but in the MFH areas only vimentin was expressed. A series of allografts in athymic mice, using tumour areas of both histological types, showed in every case a mixed pattern of tumour growth, whether the transplanted tissue was of MFH or rhabdomyosarcomatous type. This suggests that the MFH areas in the original experimental sarcomas were modulated disguised rhabdomyosarcomas. The significance of MFH-like areas in non-related soft tissue sarcomas is also discussed.

Primary osteosarcoma of the parotid gland

Four cases of primary osteosarcoma of the parotid gland, where these tumors rarely occur, are presented. This neoplasm may arise after radiation therapy, but the majority arise de novo. As a group, extraosseous osteogenic sarcomas are aggressive and lethal. Patients with these tumors have an average 5-year survival rate of 15.6%. Of the four patients reported on two died within 6 months to 3 years, one has lung metastases, and one has been lost to follow-up.

Does the pleomorphic xanthoastrocytoma exist? Problems in the application of immunological techniques to the classification of brain tumors

A case of a fibrous xanthomatous tumor of the meninges is reported. This is a rare tumor of childhood in which the characteristic pleomorphic histology contrasts with the good clinical prognosis. These tumors were reclassified as pleomorphic xanthoastrocytomas (PXA) due to their glial fibrillary acidic protein (GFAP) positivity. In the present tumor, GFAP was absent from nearly all cell bodies in most of the leptomeningeal regions of the tumor but could be detected with greater frequency at the cortical-leptomeningeal border zones and in the areas in which the tumor had infiltrated the cortex. All the tumor cells expressed vimentin and in, addition, most expressed alpha-1-antitrypsin, alpha-1-antichymotrypsin, tartrate-resistant acid phosphatase, common leukocyte antigen, and OKM1. This spectrum of marker staining corresponded not only to the pattern observed in two cutaneous fibrous histiocytomas and one malignant fibrous histiocytoma, but also to the results previously published in the literature with regard to fibrohistiocytic tumors. By contrast, this spectrum of monocytic-histiocytic marker staining was not seen in gliomas. We, therefore, regard the PXA as a mesenchymal tumor of the meninges, identical to benign fibrous histiocytomas elsewhere in the body. The possible reasons why this mesenchymal tumor can show GFAP positivity in the leptomeningeal border zone are discussed.