1 Infected corns
Corns typically develop over bony prominences, where continual pressure on the epidermis stimulates an overproduction of keratin. The overlying skin remains intact but is at risk of breaks caused by shearing forces from the hard central keratin plug.
Once the protective function of the epidermis is disrupted, bacteria can enter, leading to infection in the underlying dermis. Patients with diabetes are particularly at risk of infections.
In the case shown in the picture the resultant collection of pus can be clearly seen. The patient reported increased pain when walking and, if left untreated, was at risk of the infection spreading to the rest of the foot. A course of oral antibiotics was required.
In more severe cases incision and drainage may be required, with either oral or iv antibiotics.
2 Gout
Gout presents as a monoarthritis in 90% of cases. It most commonly affects the first metatarsophalangeal joint1, although any joint can be affected. In the case shown the left fourth metatarsophalangeal joint was affected in a patient who had a long history of gout.
Early gout usually affects only one or two joints of the lower extremities and lasts around two weeks. If repeated episodes are left untreated more joints will be affected, including proximal and upper extremity joints, and the frequency and duration of attacks will increase.
Typically, affected joints are red, hot to the touch, very tender and swollen. Aspirating the joint and looking for urate crystals in the synovial fluid can confirm the diagnosis.
Treatment in the acute phase is with NSAIDs. These have markedly reduced the incidence of joint damage and chronic tophaceous gout, which occurs when gout is left untreated. Alternative treatments include corticosteroids, colchicines and allopurinol.2
3 Hallux valgus
Hallux valgus or bunion is a medial deviation of the first metatarsal head and lateral deviation of the hallux, with or without rotation. The condition is common and painful. The prevalence is four times greater in women than in men.
Incidence increases with age. It affects 3% of people aged 15-30 years, 9% of people aged 31-60 years and 16% of those older than 60 years.
In more severe cases one of the main problems is finding shoes that fit.
There are many reported aetiological factors. These include biomechanical instability from contributing factors, such as gastrocnemius or gastrocsoleus equines, flexible or rigid pes plano valgus, or hypermobility; trauma; metabolic factors and genetic predisposition. High heels and very pointed shoes do not increase the risk of developing the condition.
There are more than 100 documented surgical procedures for hallux valgus. None are ideal, and osteotomies are continually being developed with the aim of improving outcome and reducing complications.
4 Hammer toe
Hammer toe is the most common deformity of the second to fifth toes.
It primarily consists of a flexion deformity of the proximal interphalangeal (PIP) joint, with hyperextension of the metatarsophalangeal and distal interphalangeal joints. As a result the PIP joint becomes prominent and traumatised by footwear, causing pain.
Initially the deformity is reversible, but with time the joints tend to stiffen and the toe can no longer be straightened.
Many people live with hammer toe deformities without the need for surgery. Taping and appropriate changes to footwear may be all that is required, but when pain worsens surgical intervention should be considered. This may be inappropriate if there are vascular problems or infection. Similarly, if the problem is simply cosmetic surgical correction is not usually undertaken.
The type of procedure depends on the flexibility of the toe. In cases where the joint is flexible and the deformity reversible a tendonotomy can be used; if the deformity is fixed a resection arthroplasty of the PIP joint is usually required.
5 Eczema
When eczema affects the feet and hands hyperkeratosis and fissuring often occur, which can be very painful and disabling for patients.
Differential diagnoses include:
• Palmoplantar psoriasis
• Diffuse types of palmoplantar keratoderma
• Olmsted syndrome
• Palmoplantar keratoses in Sézary syndrome and other forms of advanced cutaneous lymphoma.
Emollients are an important element of treatment. Topical steroids should also be used; a more potent strength is usually required.
Infection may occur with any breaks in the epidermis, as in the picture, which may reduce the effectiveness of topical treatments. If infection is suspected a short course of an oral antibiotic such as flucloxacillin can be helpful.
6 Bacterial infection
Venous insufficiency and the presence of varicosities may lead to the presence of varicose eczema, which causes the skin to become dry and scale. In some patients with varicose eczema, such as those with diabetes and the elderly, there is an increased risk of bacterial infection. This can rapidly lead to cellulitis, affecting the whole foot and lower leg.
In 2003-2004, cellulitis caused 49,500 admissions in England.3 A GP with an average list size of 2,000 patients will encounter cellulitis in 30 consultations per year,4 with many more patients presenting directly to secondary care.
In the case shown in the picture there was typical yellow crusting and serous fluid, along with redness and swelling. Swabbing confirmed the infection was a non-methicillin resistant Staphylococcus aureus. Oral antibiotics were given with analgesia and the patient was advised to elevate the foot.
7 Juvenile plantar dermatosis
Juvenile plantar dermatosis is a skin condition of the feet and occasionally the hands. It occurs in children, predominantly in boys aged four to eight years. In children older than eight years the condition tends to improve regardless of treatment.5
Juvenile plantar dermatosis is more common in atopic individuals. It is caused by the friction between the skin and footwear and is worse when the feet are hot and sweating.
It is more common in the summer and may take many weeks to heal. It mainly affects the soles of the feet and the toes. The skin becomes red and shiny, often with painful fissuring over the affected areas. The toe webs are not affected.
Treatment includes reducing friction by improving the fit of footwear and reducing sweating by avoiding synthetic materials and trainers, and wearing cotton socks, which should be changed regularly. Patients can be advised to coat their feet in a greasy emollient, such as white soft paraffin, which prevents the contact of sweat with the skin.
Fissures can be occluded with plasters, which speed healing and reduce pain.
8 Chronic oedema
Chronic oedema is defined as swelling of more than three months' duration that does not resolve upon elevation.
Although the limbs are most commonly affected, chronic oedema may occur in other areas, such as the trunk, genitals, breasts or head and neck.
Once fluid starts to accumulate within the tissue other changes take place. The epidermis stretches and there is a proliferation of fibroblasts and collagen fibres within the local tissue, dilatation of the local lymphatic system and increased production of inflammatory agents. Waste products and fluids accumulate in the tissue, making it hard and fibrous. The epidermis becomes thickened with marked hyperkeratosis, as shown in the picture. There is an increased risk of both bacterial and fungal infection.6
9 Pitting oedema
Pitting oedema presents as swelling of the feet and ankles that remains visibly indented when pressure is applied. Causes include congestive cardiac failure, anaemia, venous insufficiency and hypoalbuminaemia.
When the skin cannot be indented the condition is described as non-pitting oedema. This may be caused by lymphoedema.
The swelling reduces overnight. Elevation, compression stockings and treatment of the underlying condition can help.
Without treatment there is increased risk of ulceration and chronic skin changes.
Where swelling is unilateral, consider deep vein thrombosis as a differential diagnosis.
10 Palmoplantar pustular psoriasis
Palmoplantar pustular psoriasis affects the hands and the feet. It may be a localised condition or part of more widespread psoriasis. It is more common in smokers and ex-smokers.7,8 It rarely occurs in childhood and is sometimes inherited.
Groups of sterile pustules occur on the palms and plantar aspects of the feet. These may be associated with pain, scale, redness and fissuring. The condition may vary in severity and can last for many years with episodes of remission and exacerbation, the causes of which are unknown.
Treatments include emollients, topical steroids, PUVA, coal tar, acitretin and vitamin D derivatives.
It is important to warn patients that treatments will improve, rather than cure, the condition.
Recent gene studies suggest that, genetically, palmoplantar psoriasis is a distinct entity from psoriasis vulgaris and guttate psoriasis.9
11 Porokeratosis of Mibelli
Porokeratosis of Mibelli or classic porokeratosis is one of five clinical variants of porokeratosis, a clonal disorder of keratinisation characterised by one or more atrophic patches surrounded by a distinctive ridge-like border called the coronoid lamellae.
Lesions are usually few in number and may be found anywhere, including mucous membranes. They are more common on the extremities, as shown in the picture.
Risk factors for the development of porokeratosis include genetic predisposition, immunosuppression10 and ultraviolet exposure. In the case of porokeratosis of Mibelli, autosomal dominant inheritance is commonly seen.
Treatment depends on the extent of the condition and its location. Many patients will only require emollients. For those with larger affected areas, topical treatments such as 5-fluorouracil, imiquimod and vitamin D3 analogues may be helpful.11
12 Bullous Pemphigoid
Bullous pemphigoid is a blistering dermatosis. It is a chronic autoimmune sub-epidermal condition that is relatively uncommon but occurs throughout the world. Incidence is the same in men and women, with an average age at onset of 65 years (the condition usually occurring in the fifth to seventh decades of life, with only a few reported cases in childhood after vaccinations).12
The condition may last for years and, if untreated, will progress through cycles of exacerbation and remission. In those who are treated the duration ranges from 1.5 to 5 years.
Patients with aggressive or widespread disease, those requiring high doses of steroids and immunosuppressive agents and those with underlying medical conditions have increased morbidity and risk of death.
Bullous pemphigoid has been reported following other skin conditions, such as lichen planus and psoriasis, and in association with drugs such as furosemide, ibuprofen, captopril, ß-blockers13 and antibiotics. It is thought to be associated with ultraviolet light exposure and x-ray treatment.
