Dermoscopic features of difficult melanoma.
BACKGROUND
The dermoscopic diagnosis of cutaneous melanoma (CM) may be difficult because some CM lack specific dermoscopic features for melanoma diagnosis.


OBJECTIVE
To evaluate whether a diagnosis of CM could be achieved using the classic dermoscopic melanoma-specific criteria, we conducted a retrospective multicenter study of 508 CM samples.


METHODS
All the dermoscopic images were analyzed to identify the dermoscopic criteria found in dermoscopically difficult melanomas (DDM) and to examine the possible relation of dermoscopic diagnosis with respect to the difficulty of the dermoscopic diagnosis and the melanoma thickness.


RESULTS
A significant percentage of melanomas, 89 of 508 (17.5%), were DDM. The criteria leading to a significant increased risk of DDM were presence of streaks [odds ratio (OR), 2.26; 95% confidence interval (CI), 1.15-4.47), absence or presence of regular pigmentation (OR, 3.41; 95% CI, 1.70-6.85), absence of a blue-whitish veil (OR, 4.04; 95% CI, 2.33-6.99), absence of regression structures (OR, 4.31; 95% CI, 2.42-7.66), and the presence of hypopigmentation (OR, 2.61; 95% CI, 1.49-4.58).


CONCLUSIONS
A significant number of melanomas defy even dermoscopic diagnosis. Only a meticulous comparative and interactive process based on an assessment of all the individual's other nevi ("ugly ducking" sign) and a knowledge about recent changes can lead to the recognition of DDM.
Pizzichetta
Maria A
MA
Centro di Riferimento Oncologico, CRO, Aviano, Italy. pizzichetta@cro.it
Stanganelli
Ignazio
I
Bono
Riccardo
R
Soyer
H Peter
HP
Magi
Serena
S
Canzonieri
Vincenzo
V
Lanzanova
Giuseppe
G
Annessi
Giorgio
G
Massone
Cesare
C
Cerroni
Lorenzo
L
Talamini
Renato
R
D000328:Adult; D000368:Aged; D046169:Dermoscopy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D009506:Nevus / Q000473:pathology; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000473:pathology*