Armpit Rash

Essentials

• Recognize and treat factors predisposing to armpit rash (irritating topical treatments, maceration, obesity, diabetes).
• Remember the possibility of allergic contact dermatitis (fragrances, deodorants, aluminium salts, depilatory agents and skin care products).
• It is worthwhile examining other areas (the scalp, other skin areas, nails, ears) because diagnostic signs may be found there.

Diagnosis

• Does the patient have any diagnosed contact allergy? Has the patient developed reactions to fragrances, depilatory agents, cosmetics or skin care products, for example?
• Are the lesions itchy (atopic eczema Atopic Eczema (Atopic Dermatitis) in Adults, allergic contact dermatitis Allergic Contact Dermatitis)?
• Does the patient have any history of skin disorders, such as atopic eczema or psoriasis Psoriasis?
• Does the patient depilate? What method does the patient use? New hair removal technique?
• Are the armpit creases macerated (obesity, other causes)?
• Are there recurrent abscesses (hidradenitis suppurativa Hidradenitis Suppurativa)?
• Check other areas (scalp, other skin, nails, ears, etc.).

The most common causes

• Seborrhoeic eczema Seborrhoeic Dermatitis in the Adult (picture ): clearly defined erythema, usually also in areas other than the armpits, such as the scalp or the ear area
• Irritant eczema, irritant contact dermatitis Irritant Contact Dermatitis (picture ): possibly caused by deodorants, fragrances, depilatory agents, detergents, textiles
• Folliculitis Skin Abscess and Folliculitis (picture ): inflammation of single hair follicles; due to maceration, greasy topical treatments or depilation procedures?
• Intertrigo: due to maceration, obesity?
• Candidal intertrigo (picture ): erythema at the bottom of the armpit surrounded by small satellite lesions; diabetes or immunosuppression make patients susceptible to this
• Impetigo Impetigo and other Pyoderma (picture ): usually unilateral at first but can spread; clearly defined erosive surfaces covered by yellow crust, usually with few symptoms
• Atopic eczema Atopic Eczema (Atopic Dermatitis) in Adults: usually in other typical areas, as well
• Allergic contact dermatitis Allergic Contact Dermatitis: acute rash. Diagnosed contact allergy? Cosmetics or skin care products?
• Inverse psoriasis Psoriasis

Other skin problems occurring in the armpits

• Erythrasma: clearly defined, faint erythema caused by Corynebacteria, usually asymptomatic
• Hidradenitis suppurativa Hidradenitis Suppurativa: linear scars, recurrent abscesses in flexural areas, lesions often also in the groin
• Acanthosis nigricans (pictures ): bilateral, brown, thickened patches usually associated with obesity; if acute and extensive, these may suggest diabetes.
• Drug reactions Hypersensitivity to Drugs: usually symmetrically in the armpits, groins and other flexural areas, may involve vesicles (or pustules); temporal association with a drug
• Neurodermatitis (picture ): developing chronicity of another skin disease, a vicious circle of itching and scratching, often unilateral; contact allergy is possible
• Ringworm Dermatomycoses: unilateral, clearly defined, scaly at the margins, often with papulopustules
• Striae (picture ): usually associated with rapid weight gain, muscle growth or pregnancy; may also represent an adverse effect of high-potency corticosteroid ointments
• Vitiligo Vitiligo (picture ): asymptomatic, clearly defined and symmetric hypopigmented patches
• Lichen ruber planus Lichen Planus (pictures ): clearly defined erythematous bumps; when occurring in flexural areas, the clinical picture is atypical; usually also occurs in places other than the armpits; after healing, patches of hyperpigmentation may remain but treatment is futile and should not be attempted
• Hailey-Hailey disease (picture ): a hereditary skin disease with clearly defined erythema and fissures in the armpits and the groin
• Pityriasis versicolor Pityriasis Versicolor

Investigations

• Rarely necessary, the clinical picture and history are paramount.
• Bacterial culture, as necessary, if the response to empirical antimicrobial treatment of impetigo or folliculitis is poor or resistance is suspected.
• In seborrhoeic eczema, Malassezia yeast may be seen on microscopy but fungal culture may still be negative. The diagnosis should be based on clinical features.
• Epicutaneous tests Diagnostic Tests in Dermatology may be indicated if allergic contact dermatitis is suspected.
• Samples for microscopy and fungal culture if ringworm is suspected.
• If rarer skin diseases are suspected (e.g. lichen ruber planus, acanthosis nigricans, Hailey-Hailey disease), histological examination of a skin biopsy may be necessary.

Treatment

• The treatment of each skin disease is presented in the article on the respective disease.
• Causal treatment, if possible (such as reducing irritation in irritant contact dermatitis, avoidance of the causative factor in allergic contact dermatitis)
• The armpit area is particularly sensitive to adverse effects of topical corticosteroid ointments (telangiectasia, atrophy, changes in pigmentation). High to superpotency corticosteroid ointments should only be used in special cases (e.g. severe neurodermatitis) for a short period of time.
• In eczematous diseases, the treatment of first choice is intermittent low or midpotency topical corticosteroids for 1 to 2 weeks at a time, for instance.
• Topical calcineurin inhibitors (tacrolimus and pimecrolimus ointments) are also quite effective in the treatment of atopic eczema, often also in the treatment of other types of eczema and inverse psoriasis.
• Topical glucocorticoids, calcineurin inhibitors and also topical calcitriol ointment are effective for inverse psoriasis.
• For the treatment of neurodermatitis, a more potent (high potency) topical corticosteroid is often required, at first, and can be used intermittently for periods of 1-2 weeks, for example, subsequently moving over to milder, low or midpotency topical corticosteroids intermittently for 1-2 weeks at a time.
• Intertrigo or candidal intertrigo should be treated by regular washing and keeping the area dry with talc or miconazole powder, for instance, applied in the morning. In addition, intermittent treatment with a combination of corticosteroid and antimycotic ointments can be used twice daily for periods of 1-2 weeks.
• For folliculitis, topical antimicrobial solution (e.g. clindamycin) or ointment (e.g. fusidic acid) and washing with antiseptic agents (e.g. benzoyl peroxide). Extensive and severe forms of disease may require systemic antimicrobial treatment with e.g. flucloxacillin 750-1000 mg 3 times daily or cephalexin 500 mg 3 times daily in a course of 7-10 days (see also the article on abscesses Skin Abscess and Folliculitis).
• For the treatment of hidradenitis suppurativa, see Hidradenitis Suppurativa
• In erythrasma, topical treatment with fusidic acid ointment or an antimycotic ointment (clotrimazole, miconazole, tioconazole, ketoconazole) twice daily in courses of 1-2 weeks; in addition, the area can be washed with antiseptic agents (e.g. benzoyl peroxide), as necessary. In severe cases and those resistant to treatment, systemic antimicrobial treatment will help, such as erythromycin 500 mg 3 times daily or amoxicillin-clavulanic acid 750/125 mg twice daily in a course of 7-10 days.

Specialist consultation

• If allergic contact dermatitis is suspected, epicutaneous tests Diagnostic Tests in Dermatology should be performed under the supervision of a dermatologist.
• A dermatologist should be consulted in case of severe armpit rashes resistant to treatment.

Pictures