Dermoscopy in Cutaneous Amyloidosis. - A Prospective Study from India.

Sir,

Primary cutaneous amyloidosis includes macular amyloidosis (MA), lichen amyloidosis (LA), and biphasic amyloidosis. A presumptive diagnosis of cutaneous amyloidosis can be made based on the clinical features; however, a skin biopsy is required to make a definitive diagnosis. The present study aimed at looking at the dermoscopic findings in patients with cutaneous amyloidosis.

A prospective study on dermoscopy of primary cutaneous amyloidosis was conducted in a tertiary care center between July 2014 and June 2015 with the approval of the institute's review board. Forty-four patients, 37 with MA [Figure 1a] and 7 with LA [Figure 1b], confirmed with histopathology were included. Dermoscopy was done using a nonpolarized dermoscope, Heine delta 20 (Heine, Herrsching, Germany), and images were obtained using Nikon Coolpix S 9200 18X Zoom (Nikon Corp., Tokyo, Japan). The features looked for were the color of pigmentation, the presence and type of central hub, and the presence and color of dots and globules. Descriptive statistics were used. To find the association between group and categorical variables, Chi-square test/Fisher's exact test was used.

Figure 1

(a) Rippled hyperpigmentation over upper back- macular amyloidosis. (b) Hyperpigmented hyperkeratotic papules over the leg- lichen amyloidosis

The majority (29/44, 66%) of the patients were females, and most (42/44, 95%) were above the age of 30 years. The mean age at presentation was 46 years(±10 SD). The sites of involvement were arms (68%), legs (48%), and forearms (43%). A rippled pigmentation [Figure 2a] on dermoscopy as alternating parallel hyperpigmentation and hypopigmentation was seen in 65% of MA and 43% of LA, respectively, and brown dots in 97% of MA and 86% of LA. The distribution of brown dots was clustered [Figure 2b] in 68% of patients with MA and 43% with LA, scattered [Figure 2c] in 57% of MA and 11% of LA. A central hub [Figure 3a] was seen in nine patients, in 16% of MA and 43% of LA, and a spoke wheel pattern [Figure 3b] in 24%. There was no statistically significant difference in the dermoscopic findings between MA and LA [Table 1].

Figure 2

(a) Rippled hyperpigmentation with scattered brown dots on dermoscopy (arrow) (10×, nonpolarized, Heine delta 20 dermoscope). (b) Clustered brown dots (arrow) on dermoscopy (10×, nonpolarized, Heine delta 20 dermoscope). (c) Scattered brown dots (arrow) on dermoscopy (10×, nonpolarized, Heine delta 20 dermoscope)

Figure 3

(a) Central white hub with peripheral hyperpigmentation (arrow) on dermoscopy (10×, nonpolarized, Heine delta 20 dermoscope). (b) Spoke wheel pigmentation (arrow) on dermoscopy (10×, nonpolarized, Heine delta 20 dermoscope)

Table 1

Comparison between two groups and dermoscopic features of cutaneous amyloidosis

Dermoscopy	TOTAL (n=44) n (%)	MA (n=37) n (%)	LA (n=7) n (%)	P
Rippled pigmentation	27 (61.36%)	24 (64.86%)	3 (42.85%)	0.402
Brown dots	42 (95.45%)	36 (97.29%)	6 (85.71%)	0.296
Clustered brown dots	28 (63.63%)	25 (67.56%)	3 (42.85%)	0.236
Scattered brown dots	25 (56.8%)	21 (56.75%)	4 (10.81%)	1.000
Both clustered and scattered brown dots	11 (25%)	10 (27%)	1 (14.28%)	0.491
Central hub	9 (20.45%)	6 (16.2%)	3 (42.85%)	0.138
Bluish grey globules	15 (34.1%)	13 (35.13%)	2 (2.70%)	1.000
Spoke wheel pattern	9 (20.45%)	9 (24.32%)	0	-
Linear dots	5 (11.36%)	5 (13.51%)	0	-
Annular	1 (2.27%)	1 (2.7%)	0	-

Brown pigmentation on dermoscopy of cutaneous amyloidosis corresponds to basal hyperpigmentation, pigment incontinence, and melanin granules within amyloid deposition in the dermal papillae.[1] Behera et al.[2] reported clustered pigment dots in 72.9% and discrete pigment dots in 62.7% of patients. They reported a jigsaw puzzle pattern comprising pigment dots, globules, and/or peppering arranged parallelly with or surrounded by structureless white area in MA and a two-zone pattern in LA comprising a central structureless area and peripheral ridge and groove area.[2]

The classical finding described in cutaneous amyloidosis, a central hub, was seen in only nine patients (20.5%) as compared to 100% in the study by Chuang et al., 100% with MA, 44% with LA by Madarkar et al.[13] Sathyanarayana et al.[4] reported a central hub in 76% of patients with MA as compared to only 16% in our population. Behera et al.[2] reported 18.7% of hub and spoke pattern, which was similar to our study. Spoke wheel pigment pattern and light-brown radial projections meeting at a central darker clod were seen in 24% of MA, which was also reported by Kumar et al.[5] Shiny white streaks in polarized dermoscopy were described with LA by Arnold et al.[6]

The most-reported finding in the dermoscopy of cutaneous amyloidosis, the central hub pattern, was seen only in a lesser proportion of our patients. Brown dots, either clustered together or scattered, were the most common finding. Studies comparing the dermoscopic feature of cutaneous amyloidosis and its clinical mimickers will help in devising the dermoscopic criteria for cutaneous amyloidosis.

Declaration of patient consent

Informed consent has been taken from the patient.

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Conflicts of interest

There are no conflicts of interest.