Occurrence of erythemato-purpuric patches upon contact with a myriapod (diplopod)

A 40-year-old woman presented erythematous patches that evolved with hyperchromia on her left forearm after contact with a myriapod (Figure 1). She complained of a local burning sensation for the past 48 hours, and two mirrored erythemato-purpuric patches of linear configuration were present in the left antecubital fold. We noticed the occurrence of marked epidermal necrosis obscuring exogenous pigmentation, which is cited as the primary pathogenic mechanism. When pressed or crushed, diplopods tend to release chemical substances, such as quinones and hydrogen cyanide, that induce an erythemato-purpuric inflammatory process followed by prolonged residual hypo- and/or hyperpigmentation¹. Hypopigmentation results from temporary intervention of the functional activity of the epidermo-melanic unit presenting increased melanin production at the epidermis basal layer, while confetti hyperpigmentation results from follicular melanin activity. The follicular unit constitutes adnexal reserve during regenerative processes in the skin generating hyperchromic spots of follicular size and density. These macules are usually serpiginous or rounded based on the diplopod’s anatomical configuration. The tissue damage is proportional to the toxin’s nature and volume and exposure time². During rapid exposure, only exogenous pigmentation may appear. However, extreme cases carry the risk of blister formation, ulceration, and epidermal necrosis². In this case, the inflammatory response induced epidermal necrosis, which was assessed using erythemato-purpuric staining, followed by desquamation with achromia on the topography of the damage, reactionary erythema, and perifollicular hyperchromia (Figure 1). Such spots usually disappear after a few weeks or months without scarring³.

FIGURE 1:
Lesion caused by a myriapod (diplopod). (A) Myriapod (diplopod) that caused the lesion; (B) Erythemato-purpuric stained lesion; (C) Desquamation with achromia atop the damage; (D) Reactive erythema; and (E) Perifollicular hyperchromia.

ETHICAL COMMENTS

The patient signed an informed consent form. Since this is a case report, ethics committee approval was not required.

REFERENCES

• ¹
  Haddad Júnior V, Manço DG. An unusual dark macular lesion in the plantar region of a child. Rev Soc Bras Med Trop. 2019;52:e20190011.
• ²
  Radford AJ. Millipede burns in man. Trop Geogr Med. 1975; 27(3):279-87.
• ³
  Fracaroli TS, Miranda LQ, Maceira JP, Barcaui CB. Exogenous pigmentation after Diplopoda exposure leading to a dermatoscopic parallel ridge pattern on the plantar region. J Dermatol Case Rep. 2015;9(3):85-6.

Publication Dates

• Publication in this collection
  17 Dec 2021
• Date of issue
  2021

History

• Received
  10 Sept 2021
• Accepted
  06 Oct 2021