Nature of collagen in dermatofibrosarcoma protuberans

Immunohistochemical expression of matrix metalloproteinases 1, 2, 9, and 14 in dermatofibrosarcoma protuberans and common fibrous histiocytoma (dermatofibroma)

CONTEXT

Common fibrous histiocytoma (cFH) or dermatofibroma and dermatofibrosarcoma protuberans (DFSP) are 2 spindle cell mesenchymal tumors that are distinguished in part by their microscopic growth patterns and clinically by the greater propensity for DFSP to recur. Matrix metalloproteinases (MMPs) potentially play a role in modulating the growth patterns of cFH and DFSP by remodeling the extracellular matrix.

OBJECTIVE

To evaluate the immunohistochemical (IHC) expression of MMP-1, MMP-2, MMP-9, and MMP-14 in DFSP and cFH, because (1) MMP-1, MMP-2, MMP-9, and MMP-14 are synthesized by dermal fibroblasts, the major constituent of DFSP and cFH; and (2) platelet-derived growth factor B, which is overexpressed in most examples of DFSP because of t(17;22), activates ets-1, a transcription factor that regulates molecules associated with tumor invasion and metastasis, including MMP-1, MMP-3, and MMP-9.

DESIGN

Immunohistochemical studies were performed on archived, formalin-fixed, paraffin-embedded tissue of DFSP (n = 48) and cFH (n = 47).Results.-Significant IHC expression (>10% of tumor cells) in cFH included MMP-14 (27 [59%] of 46 tumors positive), MMP-2 (21 [47%] of 45 tumors positive), MMP-9 (9 [20%] of 45 tumors positive), and MMP-1 (6 [13%] of 46 tumors positive). No DFSPs showed significant IHC expression of any of the MMPs evaluated. However, anti- MMP-2 highlighted a rich microvascular element within deep tumor tissue present in 81% of DFSPs with a prominent subcutaneous component.

CONCLUSION

Our IHC results indicate that MMP-1 and MMP-9 are not up-regulated in DFSP. Convincing expression of MMP-14 in cFH suggests that this MMP may affect the growth pattern of the lesion, perhaps by activating MMP-2 expression in tumor cells. In DFSP, MMP-2 may play a role in tumor angiogenesis.

Non-polarizable collagen in dermatofibrosarcoma protuberans: a useful diagnostic aid

The stroma in dermatofibrosarcoma protuberans (DFSP) stains with trichrome, but is not polarizable (birefringent, doubly refractile). The usefulness of polarizing neoplastic stroma as a diagnostic aid in distinguishing DFSP from dermatofibroma and fibromatosis was evaluated. Forty cases of dermatofibroma of all types, 12 cases of dermal fibromatosis, and 15 cases of DFSP were examined. None of DFSPs contained polarizable collagen, whereas 11 of the 12 (92%) fibromatoses and 35 of the 40 (88%) dermatofibromas did. Of the 5 dermatofibromas that did not polarize, all were composed primarily of round to polyhedral histiocytic cells, including foam cells, frequently surrounding small obliterated capillaries. Although not pathognomonic, the presence of nonpolarizable collagen appears to be an additional histological marker useful in differentiating DFSP from dermatofibroma and fibromatosis.

Dermatofibrosarcoma protuberans: altered collagen metabolism in cell culture

Dermatofibrosarcoma protuberans is a low-grade malignant tumor that grows invasively but rarely forms metastases. Its origin is still controversial. We characterized the synthesis of collagen in detail in cells which were obtained from dermatofibrosarcoma protuberans tumors by enzymatic tissue disintegration. Similar to fibroblasts, all tumor cell strains produced considerable amounts of collagen. However, the rate was reduced compared to normal skin fibroblasts. Cells grown from the tumors synthesized type I collagen, but no type II could be detected. After serial passaging the cultures started to produce type III collagen, which is probably due to a slow overgrowth by normal fibroblasts.