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

Loss of RhoE Function in Dermatofibroma Promotes Disorganized Dermal Fibroblast Extracellular Matrix and Increased Integrin Activation

Dermatofibromas (DFs) are common, benign fibrous skin tumors that can occur at any skin site. In most cases, DFs are solitary and sporadic, but a few are multiple and familial, and the mechanisms leading to these lesions are currently unclear. Using exome sequencing, we have identified a heterozygous variant in a pedigree with autosomal dominant multiple familial DF within RND3 (c.692C>T,p.T231M) that encodes for the small GTPase RhoE, a regulator of the actin cytoskeleton. Expression of T231M-RhoE or RhoE depletion using CRISPR in human dermal fibroblasts increased proliferation and adhesion to extracellular matrix through enhanced β1 integrin activation and more disorganized matrix. The enzyme PLOD2 was identified as a binding partner for RhoE, and the formation of this complex was disrupted by T231M-RhoE. PLOD2 promotes collagen cross-linking and activation of β1 integrins, and depleting PLOD2 in T231M-RhoE-expressing cells reduced T231M-RhoE-mediated β1 integrin activation and led to increased matrix alignment. Immunohistochemical analysis revealed reduced expression of RhoE but increased expression of PLOD2 in the dermis of DF skin samples compared with that of the controls. Our data show that loss of RhoE function leads to increased PLOD2 activation, enhancing integrin activation and leading to a disorganized extracellular matrix, contributing to DF.

Relapse in dermatofibrosarcoma protuberans: A histological and molecular analysis

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a rare low grade tumor with a locally aggressive behavior and low metastatic potential.

OBJECTIVES

To evaluate the factors that are associated with relapse in DFSP. Methods Retrospective analysis of medical records from 61 patients with dermatofibrosarcoma. Fluorescence in situ hybridization was used to detect translocations.

RESULTS

Of 61 patients, 6 experienced a relapse. No patient with resection margins greater than 3 cm had a recurrence. One relapse was observed in a patient treated with at least 2 cm margins and 4 relapses occurred in 16 patients whose margins were below 2 cm (P = 0.018). The frequency of translocations was 77.8%. The recurrence rate was lower in patients with translocation, but this difference was not significant. Immunohistochemical markers did not correlate with recurrence rates, but greater FasL expression was associated with recurrence in patients with margins smaller than 3 cm.

CONCLUSIONS

Surgical margins smaller than than 2 cm are related to higher recurrences in dermatofibrosarcomas. In this analysis a 2 cm margin was acceptable for treatment. Between all the immunohistochemical markers analyzed, only FasL was associated with a higher recurrence rate in patients with margins smaller than 3 cm.

Matrix metalloproteinases in health and disease: insights from dermatopathology

Matrix metalloproteinases, a group of over 26 zinc-dependent enzymes, share a similar structure to each other and functionally are capable of degrading almost every component of the extracellular matrix. They are essential to normal development during embryogenesis and extracellular matrix remodeling and, given this, understandably enough have been implicated in multiple pathologic processes that encompass the inflammatory and neoplastic spectrum of disease. This review attempts to define roles of matrix metalloproteinases of relevance in normal skin and to elucidate their roles in inflammatory dermatoses and benign and malignant neoplasms.

Expression of MMP-2, MMP-9 and MMP-11 in dermatofibroma and dermatofibrosarcoma protuberans

Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) are the spindle cell mesenchymal neoplasms of the dermis and subcutis. Their histogenesis still remains uncertain and controversial. Traditionally, CD34 and factor XIIIa or other markers have been widely used to distinguish these two diseases. However, the results of these markers reveal overlapping and they lack specificity. Formalin-fixed, paraffin-embedded blocks were collected from the biopsied cases in Kaohsiung Medical University Hospital in Taiwan between 2004 and 2006. This study included 19 cases of DF and 17 cases of DFSP. Immunohistochemical analysis using antibodies CD34, matrix metalloproteinases (MMP)-2, MMP-9, and MMP-11 was performed. We found that the expression of CD34, MMP-2 and MMP-11 shows significant statistical differences in Immunohistochemistry (IHC) study positive or negative reactivity (positive of CD34 in DFSP and positive of MMP-2 and MMP-11 in DF; p=0.03, p<0.001, and p<0.001, respectively) between DF and DFSP. The result for expression of MMP-9 reveals no differences. The results indicate that the pathogenesis of DF and DFSP are affected by different expressions of extracellular matrix proteins. Metalloproteinases may play a direct role in these two diseases. Since no single marker can completely distinguish DF from DFSP, a combination of more than two or three stains may elevate the accuracy of diagnosis.

Morphometric analyses of elastic tissue fibers in dermatofibroma: clues to etiopathogenesis?

BACKGROUND

The etiopathogenesis of dermatofibroma (DF), a common benign fibrohistiocytic tumor, is debatable. The goal of this study was to ascertain the density of elastic tissue fibers in DF in an effort to investigate whether this provides an insight into its etiopathogenesis.

METHOD

Three groups comprising eight cellular DFs, eight paucicellular DFs and eight scars (control group) were stained with a modified Verhoeffs-van Gieson (without counterstain), and elastic fibers in three randomly selected fields within the lesional area/case semiquantitatively analyzed and examined in a blinded fashion.

RESULT

The mean density of elastic tissue fibers in cellular DF was 6.81 (1.38-15.89); in paucicellular DF, 2.46 (0.14-5.79) and in scar, 2.95 (0.97-10.69). Overall, significant differences in density of elastic tissue fibers were observed only between cellular DF and the other two groups (vs. paucicellular variant, p = 0.03 and vs. scar, p = 0.05). Morphological changes observed included thickness, clumping, elongation and waviness (cellular DF) and margination of elastic tissue fibers (paucicellular variant).

CONCLUSION

While the jury still appears to be out regarding the etiopathogenesis of DF, the reduction in density of elastic tissue fibers in the paucicellular variant compared with its cellular counterpart lends credence to the concept of evolutionary stages of DF.