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 Table of Contents  
LETTER TO EDITOR
Year : 2021  |  Volume : 8  |  Issue : 1  |  Page : 23-26

Dermoscopic evaluation of crusted scabies: A case report


1 Department of Dermatology, S. Nijalingappa Medical College, Bagalkot, Karnataka, India
2 Department of Dermatology, Krishna Institute of Medical Sciences, Karad 415539, Maharashtra, India

Date of Submission02-Apr-2020
Date of Decision28-Sep-2020
Date of Acceptance21-Jun-2021
Date of Web Publication11-Aug-2021

Correspondence Address:
Balachandra S Ankad
Department of Dermatology, S. Nijalingappa Medical College, Near APMC, Navanagar, Bagalkot 587102, Karnataka.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdpdd.ijdpdd_42_20

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How to cite this article:
Ankad BS, Koti VR, Mahajabeen SM, Nikam BP. Dermoscopic evaluation of crusted scabies: A case report. Indian J Dermatopathol Diagn Dermatol 2021;8:23-6

How to cite this URL:
Ankad BS, Koti VR, Mahajabeen SM, Nikam BP. Dermoscopic evaluation of crusted scabies: A case report. Indian J Dermatopathol Diagn Dermatol [serial online] 2021 [cited 2021 Dec 2];8:23-6. Available from: https://www.ijdpdd.com/text.asp?2021/8/1/23/323704



Sir,

Dermoscope is a non-invasive tool used in the diagnostic purposes of various skin tumors and inflammatory conditions. Its applications are expanded to diagnosis of parasitoses and infectious conditions.[1] Scabies is a contagious infection caused by mite Sarcoptes scabiei var. hominis. Crusted or Norwegian scabies is a rare and severely debilitating form, characterized by the infestation with millions of mites and hyperkeratotic lesions. Crusted scabies occurs in people with inadequate immune response to the mite.[2] Dermoscopy of scabies is well established and it demonstrates triangular brown structure that corresponds to the front part of mite. Burrow appears as tiny whitish canal. Triangular structure with whitish line resembles “jetliner with its trail” or “delta glider.”[1] We describe dermoscopic patterns in crusted scabies in Indian scenario.

A 70-year-old male presented with very itchy lesions all over the body since 1 year which produced white powdery flakes on scratching. History of itching was present in the family members. His hemoglobin was 9.7 g and he was detected to have de-novo uncontrolled diabetes mellitus with HbA1c of 7.8. On examination, hyperkeratotic scaly plaques were present over the scalp, abdomen [Figure 1]A, back [Figure 1]B, gluteal area, and lower limbs. Excoriated patches were seen in the web spaces. Dermoscopy was done with DermLite Foto II Pro with Nikon camera attached. At the center of the plaques, it demonstrated dull white crusted structures with many brown dots and globules [Figure 2]A. At the periphery of lesions, it showed numerous curvilinear whitish scaly structures with brownish curvilinear structures, black dots, and brown globules [Figure 2]B. Similar patterns were seen in the finger web spaces. Scrapings from lesions showed numerous viable mites, feces, and eggs [Figure 3]A. Histopathology revealed many mites in the stratum corneum and acanthosis [Figure 3]B. A diagnosis of crusted scabies was made, and the patient was given 12 mg of Ivermectin on days 1, 2, and 8.[3] Antihistamine, salicylic acid, and emollient preparation were given. The patient was advised to apply Permethrin 5% cream once a week for 2 weeks. After 15th day of treatment, he showed marked improvement [Figure 1]C and [D]. Repeat dermoscopy showed normal skin with mild postinflammatory pigmentation [Figure 3]C and D.
Figure 1: Clinical image of crusted scabies showing hyperkeratotic and crusted plaques on the abdomen (A) and back (B). Marked improvement in the hyperkeratotic and crusted plaques on the abdomen (C) and back (D) after treatment

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Figure 2: A: Dermoscopy of center of crusted plaques shows dull white crusted structures (yellow stars), brown globules (yellow arrows), and reddish-brown globules (red arrows). (DermLite Foto II Pro, non-contact polarized, 10× original magnification). B: At the periphery of lesions, dermoscopy reveals brown curvilinear structures (black arrows), brown globules (blue arrows), white wavy tracks (black stars), and black dots (yellow circles). (DermLite Foto II Pro, non-contact polarized, 10× original magnification)

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Figure 3: A: Oil mount of scrapings of skin lesions shows live mites (yellow arrows), eggs (red arrows), and feces (red circles). B: Histopathology shows mites (black arrow) in the burrow and acanthosis of epidermis (black star). (H&E, 100×). C: Dermoscopy of treated lesions on the abdomen shows postinflammatory pigmentation with normal skin. (DermLite Foto II Pro, non-contact polarized, 10× original magnification). D: Dermoscopy of treated lesions on the back shows postinflammatory pigmentation with normal skin. (DermLite Foto II Pro, non-contact polarized, 10× original magnification)

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Diagnosis of scabies is essentially clinical, and elicitation of classical history with itchy papules, excoriations, nodules, and eczematous eruptions gives a clue to the diagnosis. However, definitive diagnosis relies on the identification of mite in burrow. Burrows are short wavy linear tracks present in the web spaces of fingers, wrist, elbows, axillae, and shaft of the penis. Burrow is typified by tiny vesicle at the proximal end and scale at the distal end. Traditional methods to locate the burrow include “burrow ink test,” wherein fountain pen ink is smeared on the lesions and excess ink is wiped with alcohol swab to make burrow visible as ink-filled tiny and wavy track.[4]

Recently, methods of in-vivo detection of mite by dermoscopy and reflectance confocal microscopy are described in the literature. Dermoscopy of scabies shows distinct and characteristic features helping in the early diagnosis. Jetliner with its trail is the definitive dermoscopic pattern. The similar patterns were seen in this case also. The other dermoscopic features comprised of black dots, blackish-brown globules and whitish crusted structures. Generally, black and brown globules represent the location of melanin in the upper layer and lower layer of epidermis, respectively. Whereas in this case scenario, curvilinear brownish structures and brown globules represent front portion of mite and dried excoriations, respectively. White wavy track and black dots along the wavy tract correspond to burrow and eggs with feces (scybala), respectively. Reddish-brown globules correlate with melanin admixed with hemosiderin from erythrocytes. Traditional “burrow ink test” is modified by applying China ink that enhances visualization of mite by dermoscopy.[4] Reflectance confocal microscopy demonstrates tortuous segments with refractile roundish structures in crusted scabies.[5] These reports highlight the importance of non-invasive techniques in the detection of burrow.

To conclude, clinical scenario was similar to chronic plaque psoriasis or dermatitis neglecta. Dermoscopy was utilized for the accurate diagnosis of crusted scabies which was confirmed by relevant invasive diagnostic methods. It demonstrated characteristic features. It was also used to observe the improvement of lesions after treatment, which ensured the absence of mites in the lesions, although clearance of lesions was obvious clinically. There was no difference in the dermoscopic pattern in Fitzpatrick skin type VI when compared with I, II, and III. Hence, this report reinforces the utility of dermoscopy in daily practice to maximize the diagnostic outcome in crusted scabies.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given his consent for his images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Micali G, Lacarrubba F, Tedeschi A. Videodermatoscopy enhances the ability to monitor efficacy of scabies treatment and allows optimal timing of drug application. J Eur Acad Dermatol Venereol 2004;18:153-4.  Back to cited text no. 1
    
2.
Karthikeyan K. Crusted scabies. Indian J Dermatol Venereol Leprol 2009;75:340-7.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Salavastru CM, Chosidow O, Boffa MJ, Janier M, Tiplica GS. European guideline for the management of scabies. J Eur Acad Dermatol Venereol 2017;31:1248-53.  Back to cited text no. 3
    
4.
Ma Y, Hu W, Wang P, Bian K, Liu Z. Dermoscopy combined with ink staining as one more method to diagnose nodular scabies. Indian J Dermatol Venereol Leprol 2019;85:324-5.  Back to cited text no. 4
[PUBMED]  [Full text]  
5.
Uysal PI, Gurel MS, Erdemir AV. Crusted scabies diagnosed by reflectance confocal microscopy. Indian J Dermatol Venereol Leprol 2015;81:620-2.  Back to cited text no. 5
[PUBMED]  [Full text]  


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