Proliferating cell nuclear antigen staining as a prognostic indicator in soft-tissue malignant fibrous histiocytoma

Immunoglobulin G is present in a wide variety of soft tissue tumors and correlates well with proliferation markers and tumor grades

BACKGROUND

The traditional view that immunoglobulin (Ig) is produced only by B lymphocytes has been challenged, because it has been demonstrated that Ig genes and proteins are expressed in epithelial cancer cells. However, whether Ig expression in nonlymphoid cells is limited to epithelial cells is unclear. Because sarcomas differ distinctly from carcinomas in their biologic and clinical features, the authors investigated the question of nonlymphoid IgG expression in soft tissue lesions.

METHODS

Immunohistochemistry, in situ hybridization, and polymerase chain reaction (PCR) were used to demonstrate IgG expression in 80 soft tissue lesions. The correlation between Ig expression and proliferation markers (proliferating cell nuclear antigen [PCNA], Ki-67, and cyclin D1) in sarcomas was investigated by immunohistochemical and statistical analyses.

RESULTS

Igkappa was identified in 97.4% of sarcomas and in 31.7% of benign lesions by immunohistochemistry. The difference was statistically significant (P < .01). Messenger RNA from the IgG1 heavy-chain constant region was also detected by in situ hybridization. Variable-diversity-joining recombination sequences of both heavy and light chains were obtained by PCR and sequencing. Moreover, the labeling index of PCNA, Ki-67, and cyclin D1 was much higher in sarcomas with high Igkappa expression than in sarcomas with low Igkappa expression (P < .01 for PCNA and cyclin D1; P < .001 for Ki-67). There were more grade 3 sarcomas with high Igkappa expression compared with grade 1 and 2 sarcomas (P < .05).

CONCLUSIONS

IgG was identified in a wide variety of soft tissue tumors and correlated well with proliferation markers and tumor grades. IgG may be a useful marker for cell proliferation in sarcomas.

A case of subcutaneous malignant fibrous histiocytoma circumscribed by fibrous tissue

We report a case of malignant fibrous histiocytoma (MFH) located in the subcutaneous tissue on the right axilla. We excised the tumor sufficiently beyond the clinical margin. It was pathologically diagnosed as a storiform-pleomorphic type of malignant fibrous histiocytoma almost completely circumscribed by fibrous tissue, including fascicles of fibroblasts; this is a rare histological picture. The tumor has not recurred for three years. Although MFH frequently undergoes metastasis, the circumscribed-type subcutaneous MFH characteristic of superficiality and of histologically well-defined structure seems to have a relatively more favorable prognosis after adequate radical excision.