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 Table of Contents  
Year : 2021  |  Volume : 8  |  Issue : 2  |  Page : 115-116

Cydnidae pigmentation − dermoscopic features

1 Consultant Dermatologists, Sparsha Skin Care Clinic, Mandya, India
2 Department of Dermatology, Sapthagiri Institute of Medical Sciences & Research Centre, Bengaluru, India

Date of Submission03-Jan-2021
Date of Decision19-Apr-2021
Date of Acceptance08-May-2021
Date of Web Publication22-Jul-2021

Correspondence Address:
Dr. BM Shashi Kumar
Sparsha Skin Care Clinic, #1301, 2nd Cross, Neharu Nagar, Mandya 571401, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/pigmentinternational.pigmentinternational_

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Pigmented spots on the skin are caused by burrowing bugs of family Cydnidae. These are commonly seen in monsoon, and the pigmentation is due to secretion by the insect. Here we report a case of Cydnidae pigmentation with characteristic dermoscopic features. Dermoscopic features included dark brown pigmentation over the dermatoglyphics with enhanced pigmentation around the sweat pores. The pigmentation which is seen commonly over the acral areas may be mistaken for lentigines or melanoma. Identifying the classical features on dermoscopy prevents the patient from undergoing unwanted investigations.

Keywords: Cydnidae, dermoscopy, pigmentation

How to cite this article:
Shashi Kumar B, Savitha A. Cydnidae pigmentation − dermoscopic features. Pigment Int 2021;8:115-6

How to cite this URL:
Shashi Kumar B, Savitha A. Cydnidae pigmentation − dermoscopic features. Pigment Int [serial online] 2021 [cited 2022 Jun 25];8:115-6. Available from: https://www.pigmentinternational.com/text.asp?2021/8/2/115/322030

  Introduction Top

Cutaneous pigmentation by arthropods, especially of the Cydnidae family is frequently reported. The pigmentation is transient and asymptomatic. Acral lentigines and acral melanoma are considered as the differentials at times. Dermoscopic features of acral melanoma are characteristic. Herein we describe a case of burrowing bug pigmentation with dermoscopic findings.

  Case report Top

A 31-year-old patient from a rural area presented with recurrent asymptomatic black spots on the feet that would resolve spontaneously in two weeks. On examination patient had hyperpigmented, well-defined, irregularly shaped macules on both feet [Figure 1]. Dermlite 4 ® dermatoscope was mounted on a mobile and images were captured in polarized mode. Dark brown linear pigmentation along the dermatoglyphics, enhanced pigmentation around the sweat pores, and light brown pigmentation dispersed in between the lines were seen on polarized dermoscopy [Figure 2] and [Figure 3]. There was no change in pigmentation when rubbed with soap and water. The pigmentation faded and resolved completely in 2 weeks. From the above findings, diagnosis of cydnidae pigmentation was made.
Figure 1 Hyperpigmented, well-defined, irregularly shaped macules on both feet

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Figure 2 Dark brown linear pigmentation along the dermatoglyphics (yellow arrows) and light brown pigmentation dispersed in between the lines (white arrows). (10× polarized microscope with Dermlite 4)

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Figure 3 Enhanced pigmentation around the sweat pores (red arrows). (10× polarized microscope with Dermlite 4)

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  Discussion Top

Cydnidae insects also known as burrowing bugs (family Cydnidae, order Hemiptera, suborder Heteroptera, superfamily Pentatomoidea), live in soil or sand, and feed on roots or other underground parts of plants. These are harmless to humans and seen commonly in rural areas and are uncommon in urban places.[1]. A hydrocarbonate, odorous substance is produced from special glands located in its thorax that acts as a repellent and chemoattractant. This odorous substance causes reddish brown pigmented macules of bizarre shapes and varying sizes rapidly within minutes when it comes in contact with skin.[2] Accumulation of pigment in the skin furrows could be the reason for dark brown linear pigmentation along the dermatoglyphics on dermoscopy. These lesions cannot be washed off with soap and water but can be rubbed off with acetone. Junctional nevi, lentigines, and petechiae are the differentials. The dermoscopic differentiation is given in [Table 1].
Table 1 Dermoscopic differentials for cydnidae pigmentation

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Histopathological features for this condition has not been studied in detail as diagnosis is made by clinical examination in most cases. As the lesions mimic other melanocytic lesions, clinical and dermoscopic clues help to avoid misdiagnosis and subject the patient to unnecessary procedures. The sudden onset of bizarre shaped asymptomatic lesions, especially in monsoon, that cannot be rubbed off immediately and resolve spontaneously over 10 to 14 days are clues to diagnose cydnidae pigmentation.

It is a self-limiting condition and pigmentation disappears in 3 to 7 days. No specific treatment is advised.[5]

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Conflicts of interest

There are no conflicts of interest.

  References Top

Malhotra AK, Lis JA, Ramam M. Cydnidae (burrowing bug) pigmentation: a novel arthropod dermatosis. JAMA Dermatol 2015;151:232-3.  Back to cited text no. 1
Hosokawa T, Kikuchi Y, Fukatsu T. Polyphyly of gut symbionts in stinking bugs of the family cydnidae. Appl Environ Microbiol 2012;78:4758-61.  Back to cited text no. 2
Elwan NM, Eltatawy RA, Elfar NN, Elsakka OM. Dermoscopic features of acral pigmented lesions in Egyptian patients: a descriptive study. Int J Dermatol 2016;55:187-92.  Back to cited text no. 3
Poojary S, Baddireddy K. Demystifying the stinking reddish brown stains through the dermoscope: cydnidae pigmentation. Indian Dermatol Online J 2019;10:757-8.  Back to cited text no. 4
[PUBMED]  [Full text]  
Sonthalia S. Dermoscopy of cydnidae pigmentation: a novel disorder of pigmentation. Dermatol Pract Concept 2019;9:228-9.  Back to cited text no. 5


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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