Dermatology: Practical and Conceptual


Image Letter | Dermatol Pract Concept. 2024;14(3):e2024189 1

A Rare Case of Young Patient With Keloid After 
Topical Treatment with Potassium Hydroxide  

5% of Molluscum Contagiosum
Federico Bardazzi1, Tullio Brunetti1,2, Cosimo Misciali1, Giacomo Clarizio1,2,  

Camilla Loi1,2, Alessandro Pileri1,2

1 Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Policlinico S. Orsola-Malpighi, Bologna, Italy

2 Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy

Citation: Bardazzi F, Brunetti T, Misciali C, Clarizio G, Loi C, Pileri A. A Rare Case of Young Patient With Keloid After Topical 
Treatment With Potassium Hydroxide 5% of Molluscum Contagiosum. Dermatol Pract Concept. 2024;14(3):e2024189.  
DOI: https://doi.org/10.5826/dpc.1403a189

Accepted: March 9, 2024; Published: July 2024

Copyright: ©2024 Bardazzi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution-
NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, 
distribution, and reproduction in any medium, provided the original authors and source are credited.

Funding: None.

Competing Interests: None.

Authorship: All authors have contributed significantly to this publication.

Corresponding Author: Giacomo Clarizio, Department of Dermatology, IRCCS Azienda Ospedaliero-Universitaria di Bologna,  
Via Massarenti 1, 40138 Bologna, Italy 0512144843 Email. giacomoclarizio@gmail.com

Case Presentation

Keloids are the consequence of uncontrolled production and 

deposition of collagen at the point of previous dermal injury. 

Molluscum contagiosum (MC) is a benign viral infection 

characterized by small brownish, pearly, or flesh-colored 

papules with a central umbilication.

Here we present the case of a 15-year-old male patient with 

a dark phototype, a clinical history of MC in the  inguinal, glu-

teal, and internal thigh areas, and keloids in the same areas.

The anamnesis revealed that he applied topical 5% 

 potassium hydroxide (KOH) on his MC lesions, and, after a 

few weeks, he developed keloids in the areas treated.

We perform a video-dermoscopy scan, a punch biopsy 

of one keloid, and cryotherapy of remaining MC (Figure 1).

Teaching Point

It is well known that black-skinned people easily develop 

keloids; actually, there is another report about the abnormal 

cutaneous response in children following topical treatment 

of MC with KOH [1].

Pathogenesis of keloids includes the chronic inflamma-

tion of the injured reticular dermis; indeed since KOH deter-

mines a skin inflammatory process, it may have determined 

the genesis of keloids in our patient [2]. Furthermore, the 

response to inflammation could be amplified in a young pa-

tient with a more reactive immune system.

In conclusion, keloids as a possible side effect of KOH 

must be considered when it is prescribed to a young patient 

with a dark phototype.



2 Image Letter | Dermatol Pract Concept. 2024;14(3):e2024189

References

1. DI Brizzi EV, Russo T, Alfano R, Argenziano G, Piccolo V. 

 Abnormal cutaneous reaction to potassium hydroxide in mol-

luscum contagiosum in children. Ital J Dermatol Venerol. 

2022;157(1):104-105. DOI: 10.23736/S2784-8671.20.06653-5. 

PMID: 33070569.

2. Ogawa R. Keloid and Hypertrophic Scars Are the Result of 

Chronic Inflammation in the Reticular Dermis. Int J Mol Sci. 

2017;18(3):606. DOI: 10.3390/ijms18030606. PMID: 28287424.  

PMCID: PMC5372622.

Figure 1. (A) Photo of Molluscum contagiosum and keloids; (B) Molluscum contagiosum at dermoscopy scan: a central umbilication, 

roundish white-to-yellow amorphous structures, accompanied with radial vascular patterns; (C) Keloid at dermoscopy scan: a pink-brownish 

structure, with arborizing and linear vessel; (D) Histology of a keloid: thickened collagen bundles in haphazard arrangement associate with 

plump fibrocytes.