Dermatoscopy of primary localised cutaneous amyloidosis - A cross-sectional study in a setting of South Asian public dermatology department.

ABSTRACT

Background: Amyloidosis, deposition of misfolded protein in body, is a fairly common condition. The deposition of misfolded proteins in skin which occurs in absence of systemic comorbidities, namely Primary Cutaneous Amyloidosis (PCA) is also a well-known entity in skin of colour patients of Asian subcontinent. Primary Cutaneous Amyloidosis is usually diagnosed with good clinical acumen and typical clinical phenotype and involved site. Dermoscope has been used as an adjunct non-invasive tool to confirm cases with diagnostic uncertainty and in those in whom biopsy is deferred. Typical dermoscopic features of PCA helps differentiate it from other pigmentary dermatoses and avoids unwanted invasive biopsies and investigations especially in resource poor settings with financial constraints. Objectives: This study aims to identify and corroborate clinically, typical dermoscopic features in PCA in 42 patients which includes Macular Amyloidosis (MA) and Papular Amyloidosis (PA) predominantly in skin of colour patients from government based hospital of a south east Asian country. Materials and methods: Patients with classic clinical features of PCA were selected. Primary Cutaneous Amyloidosis was subclassified into MA or PA and their corresponding clinically corroborative dermoscopic features were enlisted respectively. All patients (treatment naïve and previously treated), who consented to participate in the study were included. Patients were diagnosed based on the prototypical clinical features. Dermoscopy was done using DermLite III DL3N Polarised and Fluid Dermoscope w/PigmentBoost Brand (3Gen, DermLite LLC, San Juan Capistrano, CA, USA) and images were obtained to create digital dermoscopy system by attaching camera-equipped mobile device via an optional connection kit (Redmi Note 11, MIUI version 13.0.5, CHINA) and the findings were enlisted concurrently. Results: In this study of dermoscopic findings of PCA, 42 patients were evaluated for their clinical lesions along with its corroboration with the dermoscopic features. Macular Amyloidosis was seen in 30 patients and 12 patients had typical cutaneous phenotypic and dermoscopic feature of PA. The most common dermoscopic finding seen in patients with MA was shiny to dull white, circular or oval central hub surrounded with halo of light brown dots. Most common configuration of brownish pigmentation around central hub was fine streak type. Also eccrine clues were seen in some cases of MA, which was a unique finding. Similarly in the PA subtype, the central hub was replaced by scar like structureless translucent white area surrounded by brownish black dot like structures, especially in those with large and thick plaques. Conclusion: Dermoscopic findings of PCA and their clinical corroboration is a much-needed aspect in treating patients with pigmentary disorders and in those with skin of colour, especially in developing countries. Utilization of dermoscope in clinical settings of low income countries and in government based hospitals will decrease the add on economic burden of invasive diagnostic modalities like biopsy and other inadvertent tests done to rule out pigmentary conditions.