Polarised or non polarised dermatoscopes

This is an important paper for all of us who use a dermatoscope and record images. Polarised dermatoscopes such as the Dermlite Pro (non contact) will not highlight milia in seb ks or the blue colour of deeper melanin or more importantly the blue grey veil. The nonpolarised dermatoscopes such as the Heine Delta 20 will highlight these features better. The new Dermlite fluid is equivalent to the Heine Delta 20. Those of you who were at Ash Marghoob's lecture and quiz when he presented the same lesions photographed with different dermatoscopes will appreciate how it made some of us unwittingly change our diagnosis of the same lesion presented at different stages of the quiz! Worrying!
Differences between polarized light dermoscopy and immersion contact dermoscopy for the evaluation of skin lesions.

Author(s): Benvenuto-Andrade C; Dusza S; Agero A; Scope A; Rajadhyaksha M; Halpern A; Marghoob A;

OBJECTIVE: To evaluate dermoscopic features and patterns of skin lesions by using conventional and polarized light dermoscopy (PD). DESIGN: Observational study.
SETTING: Dermatology clinic at Memorial Sloan-Kettering Cancer
Center.
PATIENTS: Ninety patients with skin lesions.
INTERVENTIONS: Skin lesions were imaged via conventional nonpolarized light contact dermoscopy (NPD), polarized light contact dermoscopy (PCD), and polarized light noncontact
dermoscopy (PNCD).
MAIN OUTCOME MEASURES: The images from the 3 modalities
were evaluated by 3 dermoscopists for colors, structures, and patterns. Level of agreement between modalities was assessed by percentage agreement and the kappa statistic. Qualitative differences between modalities were also assessed.
RESULTS: Ninety lesions comprising 55 melanocytic and 35
nonmelanocytic lesions were reviewed. There was excellent agreement for overall dermoscopic patterns between modalities, with kappa values ranging from 0.88 to 1.00. There was moderate to excellent agreement for most dermoscopic colors, with the exception of blue-white veil and pink (red) color. Most dermoscopic structures had fair to perfect agreement, with
the exception of milialike cysts. Qualitative assessment suggested that melanin appeared darker and blue nevi had more shades of blue on PD compared with NPD images; vessels and red areas were better visualized with PD, suggesting that PD may be helpful in identifying malignancies; milialike cysts and comedolike openings were better visualized with NPD, suggesting that NPD is more helpful for identification of seborrheic keratosis; peppering,
lighter colors, and blue-white areas were more evident under NPD, facilitating recognition of regression areas; and shiny-white streaks, possibly representing fibrosis, were seen more clearly under PD.
CONCLUSIONS: The capabilities of NPD, PCD, and PNCD are not equivalent, but complementary. Further studies are needed to evaluate the effect of these differences on clinical diagnosis.

Archives
of dermatology.; 2007 Mar 1;143(3)