Indian Journal of Dermatology
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Year : 2020  |  Volume : 65  |  Issue : 4  |  Page : 322-323
Comedonic isotopic response: An uncommon sequela of a common disorder

Department of Dermatology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, China

Date of Web Publication11-Jun-2020

Correspondence Address:
Cheng Tan
Department of Dermatology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijd.IJD_198_19

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How to cite this article:
Xu S, Tan C. Comedonic isotopic response: An uncommon sequela of a common disorder. Indian J Dermatol 2020;65:322-3

How to cite this URL:
Xu S, Tan C. Comedonic isotopic response: An uncommon sequela of a common disorder. Indian J Dermatol [serial online] 2020 [cited 2023 Mar 24];65:322-3. Available from:


A 53-year-old male was seen with numerous black dots on a prior site of herpes zoster. Two months earlier, he had herpes zoster over the site. Two weeks after the resolution of herpes zoster, numerous pinhead-sized pigmented dots developed at the site of healed herpes zoster. Cutaneous examination showed clusters of pinhead-sized comedones unilaterally distributed in a zosteriform pattern on the site of prior herpes zoster [Figure 1]a. The dermoscopy revealed numerous barrel-shaped comedonal openings. They were 1-3 mm in diameter, and were filled with homogeneous hyperkeratotic plugs with various shade of grey to black. Some were circled with lighter brown halos [Figure 1]b. Reflectance confocal microscopy showed enlarged infundibulum [Figure 1]c. A diagnosis of post-zoster isotopic response with comedones was rendered. The comedones gradually cleared spontaneously within two months.
Figure 1: (a) Pinhead-sized comedones unilaterally distributed in a zosteriform form on the site of prior herpes zoster. (b) Dermoscopy observation showed numerous barrel-shaped comedonal openings, which were filled with hyperkeratotic plugs and circled with lighter brown halos. (c) Reflectance confocal microscopy observation demonstrated that the infundibulum was enlarged with a bright contour or onion-like appearance

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The isotopic reaction (IR) describes the development of new skin disorders at the region of prior healed, yet unrelated skin diseases.[1] The most common primary skin disorder is herpes zoster, and less frequently herpes simplex or varicella. The interval between the episode of primary disease and the appearance of the second disorder varies from several days to months.[2] Post-zoster IR occurs as a diversity of skin conditions consisting of the granulomatous reactions, primary cutaneous malignancies and metastatic tumors, nongranulomatous dermatoses, and other miscellaneous conditions. Comedonal IR develops as a result of abnormal keratinization of the infundibulum caused by a localized inflammation.[2] An abnormal release of substance P or other neuropeptides from the impaired nerves is also crucial for inflammation of the appendages. Comedonal IR generally needs no treatment as spontaneous resolution often occurs. This report undoubtedly provides the uncommon sequela of IR over prior herpes zoster, and the dermoscopy facilitates the best view of such a phenomenon.

Declaration of patient consent

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

Financial support and sponsorship

The study was financially supported in part by the National Natural Science Foundation of China (Grant No. 81173400).

Conflicts of interest

There are no conflicts of interest.

   References Top

Ruocco V, Ruocco E, Brunetti G, Russo T, Gambardella A, Wolf R. Wolf's post-herpetic isotopic response: Infections, tumors, and immune disorders arising on the site of healed herpetic infection. Clin Dermatol 2014;32:561-8.  Back to cited text no. 1
Sanchez-Salas MP. Appearance of comedones at the site of healed herpes zoster: Wolf's isotopic response. Int J Dermatol 2011;50:633-4.  Back to cited text no. 2


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