Disseminated granuloma annulare following erythema multiforme minor

Koebner's sheep in Wolf's clothing: does the isotopic response exist as a distinct phenomenon?

Until 1995, a case of psoriasis developing within the dermatome of a healed herpes zoster was taken as a Koebner phenomenon. In this year, however, the term 'isotopic response' was introduced by Wolf et al. to describe 'the occurrence of a new skin disorder at the site of another, unrelated and already healed skin disease', thus appearing 'on apparently unaffected and healthy skin'. Initially, the term was mainly related to herpes zoster, but today the name 'Wolf's isotopic response' is used to include a plethora of other triggering factors such as healed cutaneous leishmaniasis, tinea or varicella. For obvious reasons, such triggering factors cannot be taken as examples of 'unaffected and healthy skin'. Notably, the authors themselves have categorized the dermatome of a healed herpes zoster as a 'vulnerable area'. In a recent commentary, Wolf et al. have expanded the definition of healed skin diseases triggering an 'isotopic response'. They now included 'scars, pigment changes, color changes or various other minimal changes by the first disease'. Hence, there is no clear-cut criterion to distinguish the isotopic response from a Koebner reaction. Wolf et al. even argue that, if the triggered disorder precedes the appearance of generalized skin lesions, then it is not a Koebner reaction but 'Wolf's isotopic response'. In our view, such definition is unacceptable. All reactions of this kind represent examples of a Koebner phenomenon. Accordingly, the 'isotopic response' should today be taken as a historical error.

Wolf's Isotopic Response: Report of a Case and Review of Literature

“Wolf's isotopic response” refers to the occurrence of a new dermatosis at the site of previously healed dermatosis. A number of factors including viral, neural, vascular, and immunologic factors have been implicated in the causation of this peculiar response but none has been proven conclusively. Here, we report a case where lichen planus developed at the site of dermatofibrosarcoma protruberans that had been previously treated with surgery and radiotherapy. We also put forth a hypothesis on the genesis of isotopic response considering the above mentioned factors.

Evolution of granuloma annulare to mid-dermal elastolysis: report of a case and review of the literature

A 55-year-old healthy Caucasian female, on no medication, was seen by a dermatologist because of a patchy, slightly indurated and violaceous eruption involving her neck and trunk. The clinical impression was of granuloma annulare (GA). Over a period of several months the violaceous lesions became atrophic with loss of colour and eventual wrinkling of lesional skin. Sequential skin biopsies were obtained, which revealed a spectrum of changes. Those from early violaceous lesional zones displayed perivascular lymphocytic infiltrates and interstitial granulomatous inflammation, characteristic of interstitial GA. Samples from atrophic lesional areas appeared normal on routine sections but an Orcein-Giemsa (OG) stain, prompted by the clinical history of atrophy, revealed absence of elastic fibers in the mid-reticular dermis. The combined clinicopathologic findings pointed to development of mid-dermal elastolysis (MDE) at involutional sites of GA. Owing to consideration of a cutaneous T-cell lymphoma in the differential diagnosis, genotyping in search of T-cell monoclonality was performed and yielded a negative result. Our case supports the existing but scant evidence in the literature that the rare, enigmatic condition termed MDE is an end-result of inflammatory destruction of dermal elastic fibers. GA is one form of dermatitis capable of culminating in this entity, but others have also been implicated.

Volf’s isotopic response

The term of “isotopic response” was offered by R. Wolf and co-authors in 1995 and means the development of the new dermatosis at the place of already existing initial one, which has already regressed and is not directly referred to the first one. The article describes the essence of the phenomena and most important clinical cases. Such pathogenic mechanisms as viral, immunologic, vascular, neurogenic theory are being discussed, as well as the immunocompromised site concept. The commonality and the difference of the isotopic response and of the isomorphic Kobner’s phenomenon are being analyzed. Two clinical cases are provided.