Lymphatic invasion and angiotropism in primary cutaneous melanoma

Abstract

Access of melanoma cells to the cutaneous vasculature either via lymphatic invasion or angiotropism is a proposed mechanism for metastasis. Lymphatic invasion is believed to be a mechanism by which melanoma cells can disseminate to regional lymph nodes and to distant sites and may be predictive of adverse outcomes. Although it can be detected on hematoxylin-and eosin-stained sections, sensitivity is markedly improved by immunohistochemistry for lymphatic endothelial cells. Multiple studies have reported a significant association between the presence of lymphatic invasion and sentinel lymph node metastasis and survival. More recently, extravascular migratory metastasis has been suggested as another means by which melanoma cells can spread. Angiotropism, the histopathologic correlate of extravascular migratory metastasis, has also been associated with melanoma metastasis and disease recurrence. Although lymphatic invasion and angiotropism are not currently part of routine melanoma reporting, the detection of these attributes using ancillary immunohistochemical stains may be useful in therapeutic planning for patients with melanoma.

Lymphatic invasion predicts sentinel lymph node metastasis and adverse outcome in primary cutaneous melanoma

“…Similar to some prior studies, our study detected an association between LI, as detected on dual immunohistochemistry, and SLN metastasis. We found that 33% (11 of 33) of melanomas with LI on dual D240 and S100 immunohistochemistry had a positive SLN.…”

“…Other studies have demonstrated a similar increase in LI detection with dual immunohistochemistry for D240 and S100, while Aung et al reported 46.5% LI using S100/D240 immunohistochemistry. Thus, our observation of LI in 2% of melanomas on H&E and in 26% of melanomas with the addition on immunohistochemistry lies within the published range of 0 to 8% and 16 to 47%, respectively; in prior studies, LI was detected on average in 4% of cases on H&E and in 27% of cases with immunohistochemistry . The detection rate is much higher with immunohistochemistry when compared to analysis of H&E sections, which is a strong argument for using it for routine practice.…”

Angiotropism in primary cutaneous melanoma is associated with disease progression and distant metastases: A retrospective study of 179 cases

“…Angiotropism is defined as aggregates of melanoma cells cuffing the external surface of blood vessels or lymphatics within 1 to 2 mm of the advancing primary tumor front . It has been previously identified in primary melanomas and both locoregional and distant metastases . Barnhill et al described angiotropism on H&E stained sections in 36 primary melanomas, including 35 cutaneous melanomas with an average tumor thickness of 1.64 mm.…”

“…Melanoma can behave aggressively because of its ability to metastasize even when the primary tumor is of a relatively small size. Intravascular dissemination of melanoma cells is now a well‐accepted mechanism of spread beyond the primary tumor site in melanoma and other tumors; however, other mechanisms of metastasis may exist . Extravascular migratory metastasis (EVMM) is a mechanism of melanoma spread by migration along the external surface of vessels .…”

“…Intravascular dissemination of melanoma cells is now a well‐accepted mechanism of spread beyond the primary tumor site in melanoma and other tumors; however, other mechanisms of metastasis may exist . Extravascular migratory metastasis (EVMM) is a mechanism of melanoma spread by migration along the external surface of vessels . The tumor cells are thought to show pericytic mimicry, as they replace pericytes while migrating along vascular walls .…”