Indian Journal of Paediatric Dermatology

CASE REPORT
Year
: 2021  |  Volume : 22  |  Issue : 4  |  Page : 356--359

Atypical cases of cydnidae pigmentation: Digging deeper through dermoscope


Vineet Relhan1, Pallavi Hegde2,  
1 Department of Dermatology, Venereology, Leprology, Maulana Azad Medical College, New Delhi, India
2 Department of Dermatology, Venereology, Leprology, Kasturba Medical College and Hospital, Manipal, Karnataka, India

Correspondence Address:
Pallavi Hegde
Department of Dermatology, Venereology and Leprosy, Kasturba Medical College and Hospital, Manipal - 576 104, Karnataka
India

Abstract

Arthropods can cause variety of cutaneous manifestation including pigmentation. Recently, burrowing bug pigmentation is described in the literature which though is a very common occurrence and goes underreported. Hereby, we report 2 cases of this entity presenting with atypical features to expand the clinical spectrum and to create awareness about this self-limiting condition. We have also added dermoscopic features of this entity to provide new dimension to the diagnosis.



How to cite this article:
Relhan V, Hegde P. Atypical cases of cydnidae pigmentation: Digging deeper through dermoscope.Indian J Paediatr Dermatol 2021;22:356-359


How to cite this URL:
Relhan V, Hegde P. Atypical cases of cydnidae pigmentation: Digging deeper through dermoscope. Indian J Paediatr Dermatol [serial online] 2021 [cited 2022 Jan 20 ];22:356-359
Available from: https://www.ijpd.in/text.asp?2021/22/4/356/327449


Full Text



 Introduction



Arthropods are known to produce various cutaneous manifestations in humans. Arthropod-induced pigmentation is one among them and is a common exogenous cause of sudden onset of pigmentation. Recently, burrowing bug, otherwise harmless insect, as a cause of unique pigmented spots are described in the literature. Hereby, we report dermoscopic perspective of 2 atypical cases of Cydnidae pigmentation.

 Case Reports



Case 1

A 10-year-old child was brought by his mother with a history of sudden onset of asymptomatic, dark-colored lesions over the chest and trunk. There was no history of exposure to external chemicals/dyes/attending gathering/fever, joint pain, and trauma. On further questioning, history of playing in the park, a day before the onset of lesions, where the child was accompanied by his mother was noted while mother was free of such lesions. On examination, multiple well-circumscribed, irregularly shaped, light brown-colored macules of 5 mm × 5 mm were noted on the right side of chest and abdomen [Figure 1]. The lesions could not be wiped off with soap water or alcohol rub. On performing dermoscopy, parallel furrow with branching pattern [Figure 2]a, parallel furrow with feathering pattern [Figure 2]b, and multiple light-dark brown-colored dots and clods with dark brownish-orange-colored follicular opening were observed [Figure 3]. These lesions disappeared spontaneously by 1 week.{Figure 1}{Figure 2}{Figure 3}

Case 2

An eight-year-old child was brought by his parents with a history of sudden onset of dark lesions on right side of the neck that appeared overnight. History of exposure to external chemicals or dyes/fever, joint pain, and trauma/attending any gathering/barefoot outdoor activity/playing outside was absent. On examination, multiple well-circumscribed, light-dark brown-colored macules with streaky configuration, of size 5 mm × 5 mm, were noted on the right side of neck [Figure 4]. The lesions persisted even with an attempt to remove it with soap water and acetone. Dermoscopy revealed similar findings as that of case 1. The lesions disappeared spontaneously by 10 days.{Figure 4}

Systemic examination and rest of the mucocutaneous examination were normal in both the patients. Based on the history of outdoor activity in case 1, sudden onset of lesions, asymptomatic nature, spontaneous resolution, clinical and dermoscopic findings, and a final diagnosis of Cydnidae pigmentation were established.

 Discussion



Burrowing bug is arthropods belonging to the order Hemiptera; they are so called because of their morphological adaptations for digging. They burrow in the soil and sand to feed on underground parts of the plants and commonly breed during rainy season. The pigmentation induced by the bug is attributed to hydrocarbonate containing brownish odorous substances released from the special glands for self-defense, not due to the bite.[1] On accidental crushing/pressure on to the bug, grouped, pinpoint–few mm, oval to bizarre-shaped pigmented macules with streaky and tapering edges develop within minutes of contact.[2] Although the lesions are typically described to occur on the hand and feet, rarer sites such as neck and back are also reported.[2],[3] The lesions will darken over few days followed by spontaneous disappearance over a week or so. These macules can be rubbed off with difficulty using acetone, but not with soap and water. This is one of the features that aid in diagnosis.[2] Malhotra et al. were the pioneers to report cases of Cydnidae pigmentation in three patients. Numerous dead and live winged insects were recovered from the places where the patient had probably acquired the pigmentation, and the causal role was confirmed by experimentally inducing the pigmentation on to one of the authors.[2] Subsequently, few other cases were reported. In majority of the reports, a history of outdoor activity/walking barefoot/similar lesions in family members/occurrence during rainy season was present.[3],[4],[5],[6],[7],[8] [Table 1] Both inflammatory lesions and pigmentary response to Cydnidae exposure are reported in the literature.[2]{Table 1}

Dermoscopy is an emerging, noninvasive, easy to perform, bedside diagnostic test that helps in the evaluation of various dermatological conditions. The dermoscopic finding of Cydnidae pigmentation described in literature is homogeneous black-colored areas,[4] bizarre brown-colored dots, globules, clods, stuck on appearance,[5] irregular dark brown streaks, vague rhomboidal pattern, and blackish-orange follicular openings.[3] Parallel furrows with feathering resembling a frayed rope and pigment accentuation around sweat pores are few of the other notable findings mentioned in literature.[6] The basis of various findings observed in our cases is attributed to the accumulation of pigments along skin markings and stratum corneum also the discolored keratin plug in follicular opening contributed to corresponding finding on dermoscopy.[3] The utility of dermoscopy in pigmentary disorders cannot be overemphasized as it plays an essential role in "triage" of such lesions. Brown-black-bluish pigmentation in various patterns is the hallmark dermoscopic feature of melanocytic lesions. As the burrowing bug also leaves behind similar pigmentation, it becomes important to differentiate the two. This exogenous pigmentation can be differentiated from melanocytic lesion as the findings are merely due to accumulation of pigment on the surface or follicular openings which can be rubbed off acetone and they do not follow reticular/pseudoreticular pattern.[3],[9] Nevertheless, it is important to note that few findings noted in our case can also be seen in benign melanocytic lesions such as acral lentigines. In such scenario, detailed history taking, clinical evaluation, and systemic examination help to make diagnosis.[10] The well-described features of atypical melanocytic lesions, i.e., larger, asymmetric, irregular, atypical, pigmentary network with variegated color, stand out prominently on dermoscopy and hence easily differentiated from Cydnidae pigmentation.[3]

Cydnidae pigmentation is a common entity but goes underreported due to its transient nature. Sudden onset of pigmented lesions as seen in Cydnidae pigmentation creates significant anxiety among the patients, and hence, awareness about this self-limiting condition is essential. Sudden onset, asymptomatic nature, typical site and morphology, history of outdoor activity, and occurrence during rainy season are the clinical pearls for diagnosis. When performed as a first step, dermoscopic evaluation is of great help in ruling out the benign and malignant melanocytic lesions preliminarily and hence avoiding unnecessary extensive investigations. We intend to report these cases due to the atypical location of the lesions, and the absence of supportive history as establishing the diagnosis should be made with care in such cases.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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