Dermoscopy in the Diagnosis of Palmoplantar Eczema and Palmoplantar Psoriasis: A Cross-Sectional, Comparative Study from a Tertiary Care Centre in North India

Abstract

Introduction: Palmoplantar hyperkeratotic lesions pose a diagnostic difficulty when differentiating clinically between palmoplantar psoriasis (PPP) and palmoplantar eczema (PPE). Dermoscopy can provide valuable clues in reaching the final diagnosis.

Objectives: To identify and compare dermoscopic findings seen in PPP and PPE.

Methods: This was a cross-sectional, comparative study carried out prospectively between March 2019 and June 2020. All adult, consenting patients visiting the dermatology outpatient department who were clinically diagnosed and histopathologically confirmed as PPP and PPE were recruited into two groups. The dermoscopic examination was done, and images were taken from the representative area. The findings were analysed by two dermatologists who were unaware of the diagnosis. The sensitivity, specificity, positive predictive value and negative predictive value of these findings were assessed.

Result: A total of 81 patients were recruited (39 patients of PPP and 42 patients of PPE). Significant findings seen in psoriatic plaques were the presence of regular vessels (84.6%, P < 0.001), with diffuse scales (87.2%) over a dull red/pink background (69.2%, P < 0.001). Dermoscopy of PPE displayed a significant presence of yellowish scales (76.2%, P < 0.001), with focal (61.9%) or absent vessels (35.7%), brown/orange-brown dots and/or globules (66.7%), yellow/yellow-orange crusts (57.1%) over a yellow/yellow-brown background (88.1%).

Conclusion: Distribution of vessels, distribution of scales and the colour of scales, presence of brown/orange-brown dots and/or globules, yellow/yellow-orange crust and background colour (dull red vs. yellow/yellow-brown) of the plaques can be useful clues in the diagnosis of PPP and PPE.

Keywords: Dermoscopy; palmoplantar eczema; palmoplantar psoriasis.

Figure 1

(a) Clinical image of a patient with PPP; (b) Non-polarized dermoscopic examination showing diffuse white scales in psoriasis; (c) Polarized dermoscopy in the same patient showing diffuse white scales with regular dotted vessels over dull red background; (d) application of ultrasound jelly enhanced visualization of regular dotted vessels; (e) Diffuse yellow and white scales with regular vessels over a dull red background in another patient of PPP (inset: clinical image); (f) Dermoscopy after application of ultrasound jelly showing more prominent regular vessels (black circle) over dull red background (blue star). Yellow-white lines/streaks (black arrow) also seen (Dermlite, 3Gen Inc. DL4, polarized mode, 10× magnification, images captured with Dermlite adaptor for iPhone X)

Figure 2

(a) Polarized dermoscopic examination in PPE showing diffuse yellowish scales with yellow crust (black oval) over yellow background. Vessels are not visualized. (inset: clinical image); (b) patchy yellow scales over a yellow background seen in a patient of PPE (inset: clinical image); (c) prominent dots and globules (black arrow) visualized in another patient of eczema; (d) more prominent dots and globules (blue arrow) visualized; (Dermlite, 3Gen Inc. DL4, polarized mode, 10× magnification, images captured with Dermlite adaptor for iphone X)

Figure 3

(a) Yellowish scales (blue arrow) with prominent orange-yellow crust (black arrow), patchy vessels (black box) seen over a combination of yellow (blue star) and dull red background (black star) (inset: clinical image); (b) polarized dermoscopy showing diffuse yellow scales over a yellow-brown background in a patient of eczema (inset shows clinical image); (c) Polarized examination after application of ultrasound jelly shows fewer yellowish scales with patchy vessels (black circle) visualized over a yellow-brown background. (Dermlite, 3Gen Inc. DL4, polarized mode, 10× magnification, images captured with Dermlite adaptor for iPhone X)

Figure 4

(a) Regular dotted vessels seen with patchy white and yellowish scales over a dull red background in dermoscopy of PPP. (inset shows clinical image); (b) Prominent scales seen in non-polarized mode (inset shows clinical image); (c) Polarized mode showing diffuse yellowish and grey-white scales with regular vessels over a dull red background; (d) Regular vessels appreciated more clearly after application of ultrasound jelly; (e) Dermoscopy in polarized mode displaying diffuse scales with dotted vessels (black circle) in a patient with palmoplantar psoriasis. (inset shows clinical image); (f) Dermoscopic examination after application of ultrasound jelly shows the presence of dotted vessels diffusely over a combination of dull red (black star) and yellow-orange background (blue star) (Dermlite, 3Gen Inc. DL4, polarized mode, 10× magnification, images captured with Dermlite adaptor for iPhone X)