Dermoscopic patterns of melanoma metastases: interobserver consistency and accuracy for metastasis recognition

Abstract

Background: Cutaneous metastases of malignant melanoma (CMMM) can be confused with other skin lesions. Dermoscopy could be helpful in the differential diagnosis.

Objectives: To describe distinctive dermoscopic patterns that are reproducible and accurate in the identification of CMMM.

Methods: A retrospective study of 146 dermoscopic images of CMMM from 42 patients attending a melanoma unit between 2002 and 2009 was performed. Firstly, two investigators established six dermoscopic patterns for CMMM. The correlation of 73 dermoscopic images with their distinctive patterns was assessed by four independent dermatologists to evaluate the reproducibility in the identification of the patterns. Finally, 163 dermoscopic images, including CMMM and nonmetastatic lesions, were evaluated by the same four dermatologists to calculate the accuracy of the patterns in the recognition of CMMM.

Results: Five CMMM dermoscopic patterns had a good interobserver agreement (blue naevus-like, naevus-like, angioma-like, vascular and unspecific). When CMMM were classified according to these patterns, correlation between the investigators and the four dermatologists ranged from κ = 0.56 to κ = 0.7. In total, 71 CMMM, 16 angiomas, 22 blue naevi, 15 malignant melanomas, 11 seborrhoeic keratoses, 15 melanocytic naevi with a globular pattern and 13 pink lesions with a vascular pattern were evaluated according to the previously described CMMM dermoscopy patterns, showing an overall sensitivity of 67.9% (range 54.9-76%) and a specificity of 79.9% (range 68.5-93.5%) for the diagnosis of CMMM.

Conclusions: Five dermoscopic patterns of CMMM with good interobserver agreement obtained a high sensitivity and specificity in the diagnosis of metastasis, with the accuracy varying according to the experience of the observer.

Figure 1

CMMM patterns: a. blue nevus-like pattern; b. nevus-like globular pattern; c. nevus-like nonglobular pattern; d. angioma like pattern; e. vascular pattern; and unspecific pattern.

Figure 2

Patterns and inter-observer agreement.

Figure 3

Mean sensitivity of the dermoscopist in detecting CMMM and other non-CMMM lesions.

Figure 4

Dermoscopic images of angioma and angioma-like CMMM. (a) Angioma with blood-filled vascular spaces separated by fibrous tracts, (b) thrombosed angioma, (c) and (d) angioma-like CMMM in which pseudolagoons are nests of atypical melanocytes not observed separated by fibrous tracts-like.

Figure 5

CMMM with vascular pattern. (a) Irregular dotted vessels, (b) cork screw vessels, (c) irregular linear vessels, and (d) arborizing vessels (c) and (d) mimicking a basal cell carcinoma.

Figure 6

Benign nevus with globular pattern (a) and CMMM with nevus-like pattern (b) where we observe the different appearance of globules in size, color and distribution.

Figure 7

CMMM with unspecific pattern with milky-red areas and white shiny streaks.

Figure 8

Dermoscopic-histologic correlation of CMMM patterns. (a) vascular (b) angioma-like and (c),(d) blue nevus-like. In box shows the images corresponding to each dermoscopic pattern. Hematoxylin & Eosin stain x4.

Figure 9

Histology of nevus-like pattern. (a) nests of metastatic cells, which at higher magnification (b) tendency to invade epidermis. In box shows the corresponding dermoscopic image. (a) Hematoxylin & eosin x4 and, (b) Hematoxycilin and eosin x10.