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CORRESPONDENCE |
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| Year : 2022 | Volume
: 67
| Issue : 1 | Page : 70-71 |
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| An unusual case of segmental hailey–Hailey disease developing in a 1.5-year-old child: A proposed diagnosis |
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Rudolf Happle
Department of Dermatology, Medical Center–University of Freiburg, Freiburg, Germany
| Date of Web Publication | 19-Apr-2022 |
Correspondence Address:
Rudolf Happle
Department of Dermatology, Medical Center–University of Freiburg, Freiburg
Germany
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/ijd.ijd_152_21
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How to cite this article:
Happle R. An unusual case of segmental hailey–Hailey disease developing in a 1.5-year-old child: A proposed diagnosis. Indian J Dermatol 2022;67:70-1 |
How to cite this URL:
Happle R. An unusual case of segmental hailey–Hailey disease developing in a 1.5-year-old child: A proposed diagnosis. Indian J Dermatol [serial online] 2022 [cited 2023 Jun 4];67:70-1. Available from: https://www.e-ijd.org/text.asp?2022/67/1/70/343263 |
Sir,
When I read the title chosen by Singh and Tripathy: “A rare case of childhood-onset Hailey–Hailey disease at an unusual site”,[1] I had a particular suspicion. And when I opened the article, my assumed diagnosis was confirmed. The disorder represents a classical example of a specific mosaic form of Hailey-Hailey disease.
Molecular analysis would have shown that the child is heterozygous for the HTP2C1 mutation in all cells of his body, whereas the unilateral linear lesion would reveal loss of heterozygosity resulting in loss of the corresponding wild-type allele.[2] This mutational event must have occurred at an early developmental stage, within the first week after fertilization. Hence, my diagnosis is superimposed mosaicism in Hailey-Hailey disease. (“Superimposed mosaicism” is a recently introduced term for what has previously been called “type 2 segmental mosaicism”.[2],[3]) In addition, the boy will almost certainly develop, later in life, the classical non-segmental involvement of the disorder.
In the past, superimposed linear Hailey-Hailey disease has erroneously been taken as a distinct disorder called “relapsing linear acantholytic dermatosis”.[4],[5] In one of these cases,[4] examination of the patient's mother revealed the classical non-segmental involvement of Hailey-Hailey disease, and the patient herself did also develop non-segmental lesions at 24 years of age.[2]
Finally, I hope that the authors have meticulously interrogated and physically examined the parents of this boy. For obvious reasons, it would not be sufficient to hear from the parents that “such skin disorder” has never occurred in the family.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
 References | |  |
| 1. | Singh SK, Tripathi R. A rare case of childhood-onset Hailey–Hailey disease at an unusual site. Indian J Dermatol 2021;66:92-3.  [Full text] |
| 2. | Poblete-Gutiérrez P, Wiederholt T, König A, Jugert FK, Marquardt Y, Rübben A, et al. Allelic loss underlies type 2 segmental Hailey-Hailey disease, providing molecular confirmation of a novel genetic concept. J Clin Invest 2004;114:1467-74. |
| 3. | Happle R, Torrelo A. Superimposed mosaicism in tuberous sclerosis complex: A key to understanding all of the manifold manifestations? J Eur Acad Dermatol Venereol 2020;34:2511-7. |
| 4. | Vakilzadeh F, Kolde G. Relapsing linear acantholytic dermatosis. Br J Dermatol 1985;112:349-55. |
| 5. | Arora S, Arora G, Ranjan P. Relapsing linear acantholytic dermatosis in a four-year-old boy. Indian J Dermatol Venereol Leprol 2005;71:351-3. [ PUBMED] [Full text] |
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