Conventional and three-dimensional photography as a tool to map distribution patterns of in-transit melanoma metastases on the lower extremity

Abstract

Background: In melanoma, in-transit metastases characteristically occur at the lower extremity along lymphatic vessels.

Objectives: The objective of this study was to evaluate conventional or three-dimensional photography as a tool to analyze in-transit metastasis pattern of melanoma of the lower extremity. In addition, we assessed risk factors for the development of in-transit metastases in cutaneous melanoma.

Methods: In this retrospective, monocentric study first we compared the clinical data of all evaluable patients with in-transit metastases of melanoma on the lower extremity (n = 94) with melanoma patients without recurrence of disease (n = 288). In addition, based on conventional (n = 24) and three-dimensional photography (n = 22), we defined the specific distribution patterns of the in-transit metastases on the lower extremity.

Results: Using a multivariate analysis we identified nodular melanoma, tumor thickness, and ulceration as independent risk factors to develop in-transit metastases ITM (n = 94). In patients with melanoma on the lower leg (n = 31), in-transit metastases preferentially developed along anatomically predefined lymphatic pathways. In contrast when analyzing in-transit metastases of melanoma on the foot (n = 15) no clear pattern could be visualized. In addition, no difference in distance between in-transit metastases and primary melanoma on the foot compared to the lower leg was observed using three-dimensional photography (n = 22).

Conclusion: A risk-adapted follow-up of melanoma patients to detect in-transit metastases can be applied by knowledge of the specific lymphatic drainage of the lower extremity. Our current analysis suggests a more complex lymphatic drainage of the foot.

Keywords: 3D photography; in-transit metastasis; lower extremity; lymphatic pathways; melanoma.

FIGURE 1

Overview of melanoma patients with in-transit metastases (n = 94) of the lower extremity. Definition of patients with available images taken by conventional or three-dimensional (3D) photography of the upper leg, lower leg, and foot.

FIGURE 2

Distribution of primary melanoma and in-transit metastases localized to the lower leg and foot. (A) Lateral, medial, anterior, and dorsal projection of primary melanoma (black) of 58 patients based on photographic images and mapping to distinct anatomic lymphatic drainages regions of leg: posteromedial (yellow), anteromedial (blue), anterolateral (green), and posterolateral (red). (B) Melanoma of the lower leg: three-dimensional (3D) image of a primary melanoma and corresponding in-transit metastases as well as the supposed lymphatic drainage (left image). Representative examples of individual patients with primary melanoma (black) on the lower leg with a full match of 8/8 (100%) of in-transit metastases (red) developing in the corresponding anteromedial lymphatic region (second image from the left) and metastases developing partially (8/14, 57%, second image from the right) or not predominantly within (2/10, 20%) the expected localization (right image). (C) Melanoma on the foot. Annotation of in-transit metastases (red) on a 3D photographic image (left image). Examples of representative individual patients with primary melanoma (black) and corresponding in-transit metastases (red) occurring fully, partially, or not (images second from the left, second from the right, and right) in the expected lymphatic drainage area.

FIGURE 3

Distance measurement of primary melanoma and in-transit metastases on three-dimensional (3D) photography. (A) Example demonstrating measurement of the distance (yellow line) along the skin surface between primary melanoma (black) and an in-transit metastasis (red). (B) No significant difference between melanoma of the foot compared to the lower leg is detectable concerning mean, median, and range of distances between melanoma and corresponding in-transit metastases.