Abstract
Common callouses are formed by the accumulation of keratinocytes in the stratum corneum in response to excess pressure or friction. We report 2 cases of unusual callous formation and an additional 25 more sequential cases that were due to excessive cell phone grip.
Keywords: Callous, Cell phone usage, Finger bump, Hand dermatitis
Case Reports
Case 1
A 48-year-old woman reported the development of a rough, slightly painful callous on her right thumb (Fig. 1). The condition caused mild social embarrassment when shaking hands and was occasionally painful to touch. She denied any preexisting skin conditions and was unaware of any precipitating causes.
Fig. 1.
Right thumb with callous compared to normal left thumb.
On exam, a scaly, thickened, mildly erythematous, poorly defined plaque or callous was noted extending along her right medial thumb to web space. Observation showed that the plaque corresponded to the position she carried her cell phone and she admitted to constant phone use (Fig. 2).
Fig. 2.
Position of cell phone corresponding to callous formation.
Case 2
A 58-year-old woman reported pain and tenderness over her right medial thumb (Fig. 3). Exam showed a thickened, slightly scaly, creased callous extending from the thumb to the palm. She noted symptoms had begun when she started training for a marathon and held her phone tightly in the right hand for several hours at a time.
Fig. 3.
Callous corresponding to cell phone grip.
Discussion
Wolf and Wolf [1] reported similar thumb callouses from excessive video game playing and cell phone callouses, and blisters have also been previously reported [2]. Two patients presented within a very short time frame with medial thumb callouses due to excessive cell phone gripping. Serial examination of 35 other individuals who were heavy cell phone users (Do you hold your cell phone more than 3 h a day?) showed similar bumps in 25 people. “Writer's bump” is a similar condition, which has been observed on the lateral knuckle of the third finger in individuals who tightly gripped pens or pencils. “Writer's bump” or callous is rapidly being replaced by “cell callous” or the term we prefer, “cell thumb.” Treatment would consist of keratolytic creams or repositioning the individual's grip on the phone, or better yet, putting the cell phone down altogether.
Statement of Ethics
This research was conducted ethically in accordance with the World Medical Association Declaration of Helsinki. Permission was obtained from the patients for use of photographs.
Disclosure Statement
The authors declare no conflicts of interest.
Funding Sources
None.
Author Contributions
Aleksandra L. Lindgren and Andrea Hui Austin wrote the paper and formatted it for publication. Kathleen M. Welsh conceived and designed the analysis and collected the data.
References
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