Dermoscopy aids in differentiating primary cutaneous amyloidosis and post-inflammatory hyperpigmentation: A clinico-dermoscopic-histopathaological study.

Background: Primary cutaneous amyloidosis (PCA) and post-inflammatory hyperpigmentation (PIH) are common causes of cutaneous hyperpigmentation that are usually diagnosed clinically. However, their presentations are sometimes atypical, and their differentiation is difficult. Dermoscopy is a valuable diagnostic tool for pigmented diseases that might aid in their diagnosis.

Objective: To describe the characteristic dermoscopic features of PCA and PIH together with histopathological correlation, and to differentiate between these conditions in a non-invasive way.

Methods: Fifty-two patients with PCA (n = 26) and PIH (n = 26) were enrolled. A detailed history, skin examination, dermoscopic examination using handheld and video dermoscopy, and histopathological evaluation were performed.

Results: A statistically significant difference could be detected between PCA and PIH in terms of the duration of the disease (p = 0.027), symmetry (p = 0.044), rippling (p < 0.001), and back affection (p = 0.048). On dermoscopic examination, central hubs were seen more in the PCA group (p < 0.001) with different patterns of peripheral pigmentation. Histopathologically, the number of melanophages per high-power field was significantly higher in the PCA group (p = 0.013).

Conclusion: The results of this study shed the light on the potential of dermoscopy as a non-invasive diagnostic tool in differentiating between doubtful cases of PCA and PIH.