Causes of Small Subcutaneous Blisters on the Palmar Surface of Fingers

Life-Threatening Causes to Rule Out First

The British Association of Dermatologists recommends immediately excluding Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) if the patient has fever, mucosal involvement, or widespread skin lesions, as SJS/TEN can involve palms and soles prominently with blistering 1, 2.
The presence of purpuric macules, flat atypical targets, flaccid bullae, or positive Nikolsky sign (skin shearing with minimal trauma) indicates urgent dermatologic consultation, as this condition carries significant mortality and requires immediate intervention 1, 2.
Bullous pemphigoid should be considered in elderly patients presenting with tense blisters, though this typically affects other body areas before the hands, and has twice the mortality of the general elderly population during active disease 3, 4.

The American Academy of Dermatology suggests that frequent hand washing, particularly with hot water (>40°C) and harsh soaps, causes irritant contact dermatitis with vesicle formation, which has become increasingly common during COVID-19 due to stringent hand hygiene practices 5.
Healthcare workers washing hands more than 10 times daily have a 30% prevalence of occupational skin disease, with 80% being irritant contact dermatitis, according to the American Academy of Dermatology 5.
The mechanism of irritant contact dermatitis involves lipid-emulsifying detergents and lipid-dissolving alcohols causing acute loss of surface lipids, keratinocyte release of proinflammatory cytokines leading to barrier disruption, and stripping of protective lipids making skin vulnerable to vesiculation 5.

The British Association of Dermatologists recommends first assessing for systemic symptoms (fever, malaise) and mucosal involvement to exclude life-threatening causes, such as SJS/TEN 1, 2.
The diagnostic approach should also determine the pattern and morphology of the vesicles, including deep-seated, symmetric vesicles on palmar fingers, single digit involvement with pain, vesicles with fever in children, and erythema and vesicles after increased hand washing 5, 6.

The American Academy of Dermatology recommends applying moisturizer after every hand wash, using lukewarm water, and applying moderate-to-high potency topical corticosteroids for irritant contact dermatitis 5.
For dyshidrotic eczema, the American Academy of Dermatology suggests optimizing emollient therapy with urea and paraffin applied at least daily, with more frequent applications to affected areas, and adding moderate-to-high potency topical corticosteroids (prednicarbate 0.02% or betamethasone valerate 0.1%) twice daily for 2 weeks 7.