Background/Purpose: We previously showed that fasciitis is a frequent manifestation of the disease in dermatomyositis (DM) but not in polymyositis (PM) and that DM-associated fasciitis is detected, as the result of the increased vascularity in the fascia, by power Doppler ultrasonography. We examined whether angiogenesis and vascular endothelial growth factor (VEGF)-expressing cells in the fascia are histologically identified in the early phase of DM, and whether inflammation is involved in angiogenesis and an increased number of VEGF-expressing cells.

Methods: We prospectively evaluated en bloc biopsy specimens obtained from 22 patients with DM and 11 patients with PM before treatment. Immunohistochemical staining for CD31, VEGF, and TNF-α were performed. The total vascular inflammation score (TVIS) was defined as the total number of aggregates of ≥50 perivascular inflammatory cells per 4-mm²area in the 3 fields with the most remarkable infiltration of perivascular inflammatory cells to quantify the degree of inflammation. The angiogenesis score (AS) was defined as the total number of CD31-positive blood vessels in 3 high-power fields (200×) that showed the most remarkable proliferation of the vessels. The numbers of VEGF- and TNF-α-expressing cells were counted in the 3 high-power fields (400×) that showed the largest accumulation of these cells. The TVIS, AS, and numbers of VEGF- and TNF-α-expressing cells were statistically analyzed in the fascia and muscle tissues.

Results: The AS, the number of VEGF-expressing cells, and the TVIS in the fascia of patients with DM were significantly higher compared with those of patients with PM; no significant difference was found in the muscle of patients with DM and PM. The number of VEGF-expressing cells in the fascia was correlated with the AS of patients with DM. In the early phase (the period from the onset of muscle symptoms until the biopsy <2monthes) of DM, the AS, the number of VEGF-expressing cells, and the TVIS in the fascia were significantly greater compared with the muscle. However, no significant differences were observed between the muscle and fascia in the late phase (the period ≥2) of DM. In patients with DM, the TVIS was correlated with the AS in the fascia, while the number of TNF-α-expressing cells was correlated with the TVIS and the number of VEGF-expressing cells in the fascia.

Conclusion: Angiogenesis, the number of VEGF-expressing cells, and the TVIS were higher in the fascia of patients with DM in comparison to patients with PM, and were increased predominantly in the fascia rather than the muscle in early-phase DM. Our data suggest that the angiogenesis induced by VEGF may progress from the fascia into the muscle in patients with DM. The degree of inflammation was correlated with that of angiogenesis in the fascia of patients with DM. These data suggest that the fascia can be a primary site of inflammation and angiogenesis in the pathogenesis of DM.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/angiogenesis-and-vegf-expressing-cells-are-identified-predominantly-in-the-fascia-rather-than-the-muscle-in-the-early-phase-of-dermatomyositis/