Idiopathic plantar hidradenitis

What is idiopathic plantar hidradenitis?

Idiopathic plantar hidradenitis is an uncommon condition in which there are tender, red lumps on the soles of the feet, and less often, on the palms. It has also been called palmoplantar eccrine hidradenitis and painful plantar erythema.

Who gets idiopathic plantar hidradenitis?

Idiopathic plantar hidradenitis mainly affects children and young adults, but may affect anyone.

• There is a tendency for the condition to appear in the spring and autumn. 
• It is associated with hot, humid conditions.
• Many affected individuals complain of excessively sweaty feet.

What is the cause of idiopathic plantar hidradenitis?

The cause is unknown. It is possibly a response to blocked sweat ducts as onset is often associated with heat, exercise, excessive sweating and prolonged wetness. 

What are the clinical features of idiopathic plantar hidradenitis?

Idiopathic plantar hidradenitis is characterised painful red nodules and plaques on the soles and insteps of the feet, and less often, on the palms of the hands. The surface of the skin is unaffected. Walking may be uncomfortable. It is sometimes associated with fever.

What investigations should be undertaken?

In typical cases no investigations are needed. Skin biopsies of idiopathic plantar hidradenitis may reveal neutrophils around the sweat glands. 

What is the differential diagnosis of idiopathic plantar hidradenitis?

Idiopathic plantar hidradenitis should be distinguished from hand-foot syndrome, which may arise in patients with acute myelogenous leukaemia when treated by chemotherapy.

Neturophilic eccrine hidradenitis is the name given to a chemotherapy-associated eruption of red lumps on the ears, scalp, face and trunk, in which neutrophils are also found around sweat glands.

How is idiopathic plantar hidradenitis treated?

It is recommended that affected children rest with their feet up.

• Mild analgesics such as paracetamol may be taken if needed.
• Colchicine has been reported to be effective.
• Systemic steroids may be considered in severe cases.

What is the outlook for idiopathic plantar hidradenitis?

The inflammatory reaction clears up spontaneously within 4 weeks. It may recur.