Formation of Keloid Following Herpes Zoster: A Rare Case of Wolf's Isotopic Phenomenon

Abstract

Introduction: When a new skin lesion occurs at the site of another lesion, which may be unrelated and may already be healed. It is referred to as Wolf’s Isotopic Phenomenon. It is generally seen in Post-Herpes Zoster infection (Shingles). In this case, Keloid is the new skin disease over an already healed skin lesion of Shingles. Despite of various theories, the pathogenesis of Wolf’s Isotopic Phenomenon in Herpes Zoster remains unclear. In this article, we have reported the case of a 50-year-old female who had developed Keloids on the same site where she had a history of Herpes Zoster infection.

Herpes Zoster infection is defined by the reactivation of the old infection of Varicella Zoster Virus and it spreads along the sensory nerves, presenting as blistering rashes associated with pain along the dermatomes.

The occurrence of an unrelated new lesion on the same site as an old lesion is called as Wolf’s Isotopic Phenomenon. Besides Herpes Zoster, it is also reported in Psoriatic lesions, Granulomas, Tumours of Skin or Lichen Planus

Generally, at the site of Trauma or any surgical injury, Keloids can be formed due to proliferation of Fibroblasts and excessive deposition of Collage. In addition, keloid in a post herpes zoster infection is reported very rarely, that is <1%.

Case Report: The patient was a female of age 50 years who came to the OPD having complaints of Tingling sensation and numbness of Right Upper Limb and presence of a Keloid on the chest, since 4 months. She had a history of Herpes Zoster infection 6 months ago for which she was diagnosed based on vesicular rash on the sternum and chest wall on the right side and also on the back. For which she was treated in outside hospital. She took Acyclovir for 7 days. She then observed formation of Scar tissue after 2 months on the chest wall in front of the sternum and on the back.

The Scar then expanded and progressed on the chest towards the right side and on the right arm, also on the back in the form of plaque and formed a Keloid. The Keloid was situated along the Sternal wall and lying along the T₂-T₃ Dermatome extending towards the right side both anteriorly and posteriorly along the same dermatome.

Discussion: The appearance of keloids (excessive fibrous scar tissue) in the exact area where herpes zoster (shingles) previously occurred is referred as Wolf’s Isotopic Phenomenon.

First described in 1955, it refers to a new dermatological lesion forming in the same site as another previously unrelated and healed lesion.

The development of keloids after herpes zoster is uncommon, but several mechanisms have been proposed: Post-inflammatory scarring tendency, Local immune dysregulation

Conclusion: The reported cases of Wolf Isotopic Phenomenon in patients of Herpes Zoster are very rare and hence the risk may be underestimated. Further research and studies are important to understand the Pathogenesis and epidemiology and will also help in management of such Cases.