Environmental and Sports-Related Skin Diseases

Published on 05/03/2015 by admin

Filed under Dermatology

Last modified 22/04/2025

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74

Environmental and Sports-Related Skin Diseases

Cutaneous Injury Due to Heat Exposure

Thermal Burns

Traumatic injury to the skin caused by an external heat source.

The depth of the burn injury depends on the temperature of and the amount of contact time with the heat source as well as the thickness of the affected skin.

The burn depth determines the severity and classification of the injury, its potential for healing and need for surgical intervention (Table 74.1).

In 2009, the American Burn Association replaced the traditional classification of burn wounds (i.e. first-, second-, third-degree) with a system that reflects the need for surgical intervention (see Table 74.1; Fig. 74.1).

An exact classification of the burn injury may not be possible upon initial presentation and may take up to 3 weeks to determine; burns may be deeper than initially suspected when occurring on thinner skin (e.g. in pediatric and elderly patients; on ears, volar forearms, medial thighs, and perineum).

The extent of burn injury is expressed as a percentage of the body surface area (BSA) involved and is essential for guiding therapy and determining a patient’s disposition (e.g. hospital admission for a partial-thickness burn involving >10% BSA in an individual 10–50 years of age).

The most accurate method for estimating BSA involvement in adults and children is the Lund–Browder chart (http://www.tg.org.au/etg_demo/phone/etg-lund-and-browder.pdf); the ‘rule of nines’ method is perhaps more expeditious in adults, but it cannot be used for children (Fig. 74.2).

General principles of treatment are outlined in Table 74.1.

Erythema Ab Igne

Localized areas of reticulated erythema and hyperpigmentation due to chronic exposure to heat that is below the threshold for a thermal burn.

Multiple heat sources have been implicated (Table 74.2).

Most commonly seen in the lumbosacral region (due to heating pads applied to relieve pain from degenerative spinal disease); more recently seen on the anterior thighs from heated batteries in laptop computers.

In long-standing erythema ab igne (latency period ≥30 years) there is an associated risk of malignant degeneration, resulting in thermal keratoses and SCC.

Early lesions: asymptomatic, initially transient, blanchable macular erythema in a broad, reticulated pattern that corresponds to the venous plexus; size and shape approximates that of the heat source (Fig. 74.3A).

Later lesions: dusky reticulated hyperpigmentation; lesions are fixed and no longer blanchable (Fig. 74.3B).

End stage: may become keratotic and bullae may appear.

DDx: livedo reticularis, cutis marmorata, poikiloderma (e.g. due to CTCL, dermatomyositis, several genodermatoses); the latter has a tighter net-like pattern.

Rx: remove the heat source; if applicable, identify and treat the underlying source of pain.

Cutaneous Injury Due to Cold Exposure

Pernio (Chilblains)

An abnormal inflammatory response to cold, damp, nonfreezing conditions.

Classically presents with single or multiple erythematous to blue-violet macules, papules, or nodules distributed symmetrically on distal toes (Fig. 74.6) and fingers, and less often on the remainder of the foot or hand, nose and ears.

In severe cases, blistering and ulceration may be seen.

Patients describe pruritus, burning, or pain; histology demonstrates a perivascular and perieccrine lymphohistiocytic infiltrate.

Lesions typically resolve in 1–3 weeks but can take much longer or become chronic in elderly patients with venous insufficiency.

DDx: chilblain lupus; frostbite; lupus pernio (a variant of sarcoidosis involving mainly the nose and ears) (Table 74.3).

Rx: adequate clothing; avoidance of cold, damp conditions; keeping feet dry; avoidance of smoking; and use of nifedipine in recalcitrant cases.

Cutaneous Injury Due to Chemical Exposure

Cutaneous Findings Resulting from Toxic and Heavy Metal Exposure

Cutaneous Findings of Frictional and Traumatic Injury to the Skin

Corns and Calluses

Keratotic lesions resulting from repeated trauma and the subsequent cycle of friction, pressure, and thickening (Fig. 74.8).

Contributing factors include ill-fitting footwear, bony protuberances, abnormal biomechanical foot function, and specific activities that involve repetitive activity.

Hard corns are usually located on the dorsal aspects of the toes, while soft corns are typically found in the interdigital web spaces.

Corns and calluses can often be mistaken for verrucae; gentle paring of the lesions with a blade and noticing the lesion’s effect on dermatoglyphics can help distinguish between these three entities (Table 74.7).

Treatment involves both symptomatic relief and correction of the underlying biomechanical problem:

Symptomatic relief.

1. Paring of the callosity with removal of the corn’s central core may bring immediate relief of discomfort, followed by periodic foot filing.

2. Application of keratolytic agents (e.g. 40% salicylic acid pads; 6% salicylic acid, 10–40% urea, or 12% ammonium lactate creams), from daily to twice weekly, depending on strength.

3. Soft cushions (e.g. silicone sheet, sheep skin) and donut-shaped corn pads.

Biomechanical correction – properly-fitted footwear and use of appropriate orthotics.

Recalcitrant lesions – consider x-ray to look for exostoses and referral to orthopedic or podiatric surgeon.

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