Whereas in other parts of the body skin tags (acrochordons) may be nothing more than an unsightly nuisance, in the axilla they might cause problems if they rub and become sore or infected. These common benign lesions are seen more often in obese patients and are most likely to occur on the neck and intertriginous regions such as the groin or axilla. They may vary in size up to about 5mm in diameter. Often they are associated with the human papilloma virus or type-2 diabetes. Ligation, cryotherapy or excision may be useful where treatment is required.
Neurofibromatosis is a genetically inherited disorder, of which one particular feature is light brown patches on the skin, known as cafe au lait spots. These might be present at birth or develop during childhood. More than five of these should be present before the diagnosis of neurofibromatosis can be made. Later in childhood or adolescence, dome-shaped, soft, pedunculated or subcutaneous nodules occur or nodules that may involve other tissue such as bone, muscle, central nervous system or blood vessels. One sign that is said to be pathognomonic of the condition is freckling in the axilla and groin (pictured).
This bacterial infection of the skin occurs most commonly on the hands, face or in the axilla. Streptococcus pyogenes or Staphylococcus aureus are usually responsible for the problem. This boy developed pustules in the axilla that rapidly spread and broke down to leave this sore, moist, weeping area. The area was bathed with an antiseptic lotion and fucidic acid ointment applied three times a day until clear, and for a few days afterwards. As there was no sign of impetigo in other areas, and the lesion quickly settled, an oral antibiotic was not required.
Erythrasma is caused by the bacterium Corynebacterium minutissimum. It occurs in intertriginous areas such as the groin, axillae, under the breast and between the toes. It is most common in diabetics and the obese. The patient presents with a well-defined patch of pink or brown dry, wrinkly skin. The diagnosis can be confirmed by taking a skin scraping for microscopy or culture or by examining the lesion under Wood's lamp, when a coral pink fluorescence is induced. Topical treatment with an imidazole or fusidic acid cream will usually clear the problem, as will a course of oral erythromycin or tetracycline.
This child had just had chickenpox when he presented with a rash under his left arm and on his left side. Small blisters, filled with pus, could be seen, some of which were crusted ulcers. Ecthyma is a skin infection which, like impetigo, is caused by S pyogenes or Staph aureus. The difference is that ecthyma lies deeper in the skin. It might follow any skin damage, such as an insect bite or where chickenpox spots have been scratched. Topical antibiotic creams such as mupirocin should be sufficient to treat localised lesions but oral antibiotics (penicillin) may be required in persistent or more widespread cases.
Seborrhoeic eczema, with a facial, non-itchy rash particularly affecting the alae of the nose and the eyebrows and dandruff of the scalp, is commonly seen in the surgery.
Less often the condition is seen in the flexures, as in this man with a bright red, sore scaly area in the axilla. It is associated with an overgrowth of the yeast Pityrosporum ovale. It does not develop until after puberty and is more common in patients with Parkinson's disease and those who are HIV positive. In the axilla, weak topical steroids with an imidazole cream should clear the rash, but recurrences are always likely.
Patients with hidradenitis suppuritiva present with recurrent abscesses that occur most commonly in the groins, axillae and under the breasts, although other areas such as the nape of the neck, waist and inner thighs are sometimes affected. The cause of this condition is unknown but infection (usually staphycococcal) follows follicular plugging of the apocrine ducts and subsequent rupture of the follicular epithelium. Solitary or multiple abscesses and sinus tracts may then develop. It is more common in women and tends to occur in patients aged 20-40 years.
Treatment includes bathing the area with an antiseptic lotion, and patients should be advised to cease smoking and lose weight. In the acute phase, an oral antibiotic such as flucloxacillin is required. Tetracycline or metronidazole, for at least three months, might help to reduce recurrences by their anti-inflammatory action, and three months of clindamycin or rifampicin may also be tried. The condition is also helped by isotretinoin. Intralesional steroids may help severe inflammatory lesions. This patient had improved after excision of the affected area and skin graft.
Contributed by Dr Jean Watkins, a sessional GP in Hampshire.
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