SKIN RASHES: TAKING THE HISTORY

In order to successfully diagnose a skin rash, you need to know which questions to ask.

Timing is an important factor to consider. How long has the rash been there, does it come and go? Did the rash look different when it first occurred, and how has it changed? If it occurred before, what was it and what treatment worked?

Associated symptoms can be key in making the right diagnosis. Does it itch, burn, or is it painful? Are there any fevers, chills, pain anywhere else in their body?

Related activities that may have caused or worsen the rash should be investigated. This includes things like sunlight exposure, being out in the woods, using a new skin product like shampoos or lotions, or new medications or foods.

Treatments that the patient has already tried should be evaluated, which usually includes OTC creams and sometimes prescribed medications from a previous diagnosis or from another recent healthcare visit. This may be Benadryl cream, steroid cream (like hydrocortisone), moisturizers, etc.

A detailed past medical history and current medications should be evaluated as well. Meds that are more likely to cause a rash include:

• Antibiotics
• Anti-epilepsy medications
• allopurinol

THE SKIN RASH PHYSICAL EXAM

When looking at skin rashes, they are described using various describers which have different meanings and significance. A lesion is a general umbrella term that essentially means any non-normal “spot” or region.

These lesions and skin rashes can present in certain patterns and distributions, which can also help you successfully identify the rash.

Skin rashes can be clustered in small groups, grouped together in some fashion, linear (in a line), following the dermatome (termed zosteriform), and even coalescing together. Various rashes have certain patterns which can make the diagnosis easier.

– 20 Common Skin Rashes –

Allergic Skin Rashes

CONTACT DERMATITIS

Contact dermatitis is when the skin has a reaction to something that it has come into contact with. 80% of cases are caused by an irritant, and 20% are caused by allergens. Contact dermatitis is the most common dermatologic diagnosis.

The skin will typically look erythematous, dry, and irritated. There may be pustules present as well.

In Allergic contact dermatitis, common causes include nickel, black hair dye, topical medications, latex, and various cosmetics and environmental exposures (like poison ivy or poison oak). Allergic dermatitis tends to be itchier with less pain or burning. There may be vesicles present as well.

Treatment for these includes steroids for the reaction, and benadryl for the itching. If the lesion is smaller, a topical steroid like Triamcinolone 0.5% once daily for 2-4 weeks can be effective. If the lesion is more widespread, systemic steroids can be used like oral prednisone.

Allergic Urticaria

Urticaria or hives are itchy raised wheals that are often erythematous or pale. They are often a response to an allergy such as in anaphylaxis, but many cases of urticaria are non-allergic and some are idiopathic (aka we don’t know why).

Allergic urticaria occur after contact with an allergen. These allergens can be in the environment (like dust or pollen), in food (like nuts or dyes), and in medications like with antibiotics. Urticaria can also occur after bug bites and stings.

Treatment for urticaria skin rashes depends on the underlying cause, but in cases of allergic causes, treatment includes anthistamines like benadryl, and sometimes steroids like prednisone.

Eczema

Eczema, also termed atopic dermatitis, is a chronic allergic-related chronic skin condition which is very itchy.

“The Itch that Rashes”

In adults, eczema skin rashes often occurs on skin flexures like the elbows and behind the knees, on the face, neck, and hands, but can occur anywhere. All patients with eczema should liberally use a water-based emollient moisturizer like Cetaphil, Aquafor, or CeraVe. Since eczema is a chronic condition, it cannot be taken away completely, but there are treatments that can help.

Depending on the severity of the eczema, lower or higher strength steroid creams can be used once or twice daily for 2-4 weeks.

• Low Potency: Hydrocortisone 2.5%
• Mid Potency: Triamcinolone 0.1%
• High Potency: Usually not prescribed for eczema

For more severe eczema, topical calcineurin inhibitors can be used as well or even monoclonal antibodies. A dermatologist should be the ones to prescribe these advanced medications.

Autoimmune Skin Rashes

Psoriasis

Psoriasis is a type of chronic autoimmune skin rash condition. This is characterized by erythematous flaking thick patches of skin. They can be itchy and even burn.

Treatment for psoriasis depends on the severity of the disease, but can range from topical steroids, retinoids, tacrolimus, or at times systemic steroids and immunomodulators.

Malar Rash

Malar rash, often termed the “butterfly rash,” is a hallmark facial rash that appears over the cheeks and bridge of the nose. It is frequently associated with Systemic Lupus Erythematosus (SLE), a chronic autoimmune disorder.

The malar rash has a distinctive red, flat, or raised pattern, resembling the wings of a butterfly. It does not usually itch or cause pain but can be sensitive to sunlight. Sun exposure can trigger or worsen the rash.

While the malar rash is highly suggestive of SLE, it could be rosacea or something else. A history of other systemic symptoms like fatigue, joint pain, and photosensitivity can help point towards SLE.

The underlying cause of the rash is the body’s immune system attacking its own tissues. SLE can affect many parts of the body, and the malar rash is just one possible manifestation.

Treatment for the malar rash primarily aims at treating the underlying SLE. ANTIMALARIALS, such as HYDROXYCHLOROQUINE, are often prescribed to reduce the severity and frequency of lupus symptoms, including the malar rash. SUN PROTECTION is also very important. Patients are advised to use broad-spectrum sunscreens and wear protective clothing. In more severe cases or flare-ups, STEROIDS might be prescribed to control inflammation.

Viral Skin Rashes

Shingles

Shingles, also called Herpes zoster, occurs from reactivation of inactive varicella virus within the body (the chicken pox virus). Shingles almost always occurs in adults and usually in patients older than 50 years old. 

Treatment involves pain control. Antivirals like acyclovir can be started within 72 hours that the lesion develops, otherwise they are unlikely to be beneficial.

Shingles is very contagious, especially if any vesicles pop open until the lesion scab over.

Pityriasis Rosea

Pityriasis rosea is a self-limiting rash thought to be secondary to viral infections. Skin rashes and reactions secondary to viruses are termed viral exanthems. This is often preceded by a viral prodrome including headache, malaise, arthralgias, and/or chills.

Pityriasis rosea starts as a herald patch which is a single oval-shaped erythematous macule or patch on the trunk with central clearing. 1-2 weeks later, a christmas tree pattern will appear on trunk with similar smaller lesions.

There is no specific treatment for pityriasis rosea, and only time will cause the rash to resolve. Pityriasis can be itchy so benadryl can help. This is not contagious.

Hand Foot and Mouth Disease

Hand Foot and Mouth disease is a viral rash that occurs due to the Coxsackie Virus A16 and some other enteroviruses.

While HFM usually affects children, it can easily spread to parents and family members via droplets. Adults and teenagers will often have systematic symptoms including fevers, body aches, and flu-like symptoms. HFM may be preceded by upper respiratory symptoms by a few days. 

The HFM rash appears on the palms, soles, buttock, and mouth of patients. The oral lesions have football shaped vesicles that are very painful and are on the soft palate, buccal mucosa, gums, and tongue. The posterior pharynx is unaffected. 

Skin lesions are red papules with a red halo, then become gray vesicles, then ulcers after the vesicles rupture, then heal 7-10 days later. 

Like all viruses, treatment is symptomatic. Antipyretics and NSAIDs for pain and fevers and topical lidocaine for painful oral lesions. Keeping the patient well-hydrated is very important. 

In severe cases, the patient can have altered mental status from encephalitis or myocarditis.

Measles

Measles, once nearly eradicated in the US, has begun to make a comeback, largely due to the growing Anti-Vax movement. The measles, caused by the morbillivirus, causes 150,000 deaths per year worldwide, usually in those less than 5 years old.

The rash starts on the forehead and spreads to the face, neck, trunk, extremities. It spreads to the palms and soles in 50% of patients. 

Koplik spots are small white spots with red halos in the mouth on the inside of the cheeks that occur early in measles, which is very specific to measles.

Treatment is largely supportive with antipyretics, analgesics, vitamin A, and hydration.More severe cases will need hospitalization and sometimes the antiviral medication Ribavirin.

Fungal Skin Rashes

Intertrigo

Intertrigo is inflammation and infection of the skin folds, usually in obese individuals with diabetes. This is often a fungal infection, but can have a bacterial component as well.

Common sites include the groin, axillae, underneath the breasts, and in-between fat rolls.

These places will often be itchy, burning, and may smell bad.

When in the groin region, this is often called tinea cruris.

Prevention and treatment includes measures to reduce friction, reduce moisture (talcom powder), use of barrier cream or ointment, and wearing breathable fabric.

The fungal infections can be treated with topical antifungals including clotrimazole cream or nystatin powder 2-3x per day.

Tinea Corporis

Tinea corporis, also known as ringworm, is a fungal infection of the trunk or extremities. This is spread via skin-to-skin contact with an infected individual or animal, but can also be picked up by fomites. This is also common in athletes like wrestlers and in warm-moist locker rooms where fungus likes to live.

Treatment involves the use of topical antifungals 1-2x/day for 1-3 weeks. An example includes Clotrimazole 1% BID. More severe infections may need oral antifungals.

Bacterial Skin Rashes

Cellulitis

Cellulitis is a local bacterial skin infection. This starts as some sort of breach to the skin barrier (small cut or puncture), and subsequent infection of the skin and surrounding soft tissue.

Cellulitis presents as localized erythema, edema, pain, and warmth to touch. This often presents in a unilateral leg, but can present anywhere on the body.

Cellulitis may be associated with systemic symptoms such as fevers, chills, and generalized malaise. Sometimes abscesses can form.

Cellulitis is treated with PO antibiotics, but if significant systemic symptoms, high risk, or severe disease – IV antibiotics may be necessary.

• PO: keflex 500mg QID x 7 days
• IV: Ancef 1gm q8h

MRSA is resistant to certain antibiotics such as those above. The following antbiotics should cover MRSA:

• PO: Bactrim, Clindamycin, or Doxycycline
• IV: Vancomycin, Linezolid, or Daptomycin

Folliculitis

Folliculitis is a bacterial infection of the hair follicle, usually caused by staph aureus.

If mild, folliculitis is self-limiting and may not need any specific treatment. A topical antibiotic like Mupirocin ointment TID x 7 days can be used.

More significant folliculitis can be treated with PO antibiotics like dicloxacillin, keflex, or another antibiotic with good gram positive coverage. If MRSA is suspected, MRSA covering agents would need to be used (see above).

Furuncle

A furuncle is a larger painful infection of a hair follicle which is deeper than folliculitis. Another term for furuncle is a boil.

Multiple furuncles can coalesce together to form a carbuncle.

Smaller lesions can be successfully treated with warm compresses, but larger more significant lesions will need treated with Incision & Drainage.

PO antibiotics are often given, however may not be necessary if I&D is performed. They should be given if there is cellulitis present, significant comorbidities like diabetes, with systemic symptoms, or unreliable follow-up. 

PO antibiotic choices are the same for cellulitis, except MRSA should probably be covered regardless.

Personal hygeine should be encouraged as this can help prevent skin abscesses from occurring.

Bite-related Skin Rashes

There are plenty of bugs that can bite, sting, and infest our skin, leaving skin rashes behind.

BED BUGS

Bed bugs inhabit typically houses and beds that are somewhat unclean (very common in group homes and homeless shelters). These bugs feed on blood which causes a local reaction in the skin.

Treatment includes benadryl for itching, and if there is significant itching, a low to medium potency topical steroid can be used.

Maintaining good hygiene is essential, and a pest service will need to be used to clear out an infestation.

Flea Bites

Flea bites occur when fleas are transmitted from animals to humans. This is usually due to infested domesticated cats or dogs who transmit the fleas to their owners.

When a flea bites, it will cause pruritic papules, most common on the ankles. They may be randomly placed, but sometimes they appear in groups or clusters.

An antihistamine like benadryl or zyrtec can be given for itching. Ice packs and calamine lotion can also help with the itching. Topical steroids are usually not necessary but can help.

Prevention is important. Regularly cleaning and vacuuming can reduce the risk of infestations. For households with pets, ensuring that pets are treated for fleas with appropriate treatments is essential. 

Spider Bites

Spider bites are actually pretty rare, as many spiders do not have fangs strong enough to pierce human skin. They also usually do not bite unless they are provoked or about to be squished.

When there is a real spider bite – a papule, pustule, or wheal will appear. Two small central fang marks can often be visualized in the center. The most common areas are in the axillae, the waist, and the ankles/feet.

Most spider venoms are benign and only cause a local reaction. Black widows, funnel web, and phoneutria spiders are more poisonous and the patient may have systemic symptoms including body aches, hypertension, tachycardia, abdominal pain, etc.

Brown recluse spiders can cause systemic symptoms, but often causes a more significant local reaction with potential necrosis.

Treatment for simple spider bites involves cleaning the area, and they should spontaneously resolve in 7-10 days. If there is associated cellulitis, appropriate antibiotics should be given as above. More severe reactions may need more supportive care and hospitalization.

Scabies

Scabies is more common in children but can happen in adults as well. It is also associated with poor hygiene and crowded living conditions similar to bed bugs.

Scabies rash appears initially as tiny to small erythematous papules, and will often form vesicles or pustules. They will often present in lines as the mites burrow through the epidermis. This can be easily noticeable in the web spaces of the fingers, wrists, and elbows.

Scabies is very itchy as well, and itching may persist 2-6 weeks after treatment.

Benadryl can help with the itching, but scabies will need treated with Permethrin 5% cream applied to the entire body, left on overnight (8-14 hours), and washed off in the morning. This should be reapplied in one week.

Everything else in the house that could be infested should be cleaned. Bedding and clothing within the last 48 hours should be washed in hot water and heat-dried. Non-washable items should be placed in plastic bags for at least 1 week (stuffed animals, etc).

Erythema Migrans

Erythema migrans is the “bulls-eye rash” of early lymes disease.

The initial rash will be a small red painless papule, which will expand over a few days and turn into a circular erythematous rash with central clearing and induration. This resolves in weeks if left untreated.

Patients with Lyme disease will typically present with systemic symptoms including fevers, chills, malaise, and body aches.

Treatment for this rash is the treatment of the underlying Lyme disease. Lyme disease should be treated with doxycycline 100mg BID x 21 days.

Be sure to have your patient EAT with and directly after doxycycline, as it can cause significant GI upset and pill esophagitis.

That’s a wrap on our deep dive into 20 common skin rashes, what they look like, and how they’re treated. If something looks or feels off, it’s always a good shout to check in with a dermatologist or even your PCP. 

References