Discuss the possible causes and the resultant pathological changes that occur in the soft tissues in the development of a hard corn on the plantar aspect of the 2nd metatarsal head.

Give the clinical features, symptoms and possible aetiology of a soft corn in the webbing between the 4th and 5th toes of a 40 year old female.

A heloma durum is a localised thickening of epidermis due to excessive intermittent pressure and friction, meeting with constant resistance occurring over a bony prominence.

Possible causes of this corn include toe deformities such as claw toes, hammer toes and retracted toes. In all 3 of these deformities the metatarsal phalangeal joint is dorsiflexed, putting greater pressure on the head of the metatarsal which is where this corn is located.
Abnormal foot function such as forefoot varus or rigid or mobile forefoot valgus could be another possible cause.
Poorly fitting footwear, for example, shoes with a small, narrow toe box.
The cause could also be due to the individual's occupation. For example, a person who works in retail may have to stand for long periods of time, therefore putting more pressure on the metatarsal heads.
Obesity is another possible cause, as is a lower tolerance level of the tissues due to age, diabetes, skin disorders, poor circulation, medication (steroids).
Friction will cause irritation/trauma to the tissues which stimulates the cells of the epidermis. It also causes hyperaemia (increased blood supply to area). This in turn leads to increased mitotic division. When the skin is injured the basal layer proliferates to repair the epidermis. Additionally the Stratum granulosum also thickens and becomes disrupted.Dermal papillae and epidermal ridges elongate. There is also marked thickening of, along with decreased desquamation of the cells from the Stratum corneum and thickening of the epidermis. In the dermis there may be evidence of new capillary formation in response to demand of new cells. Skin changes are the result of local biochemical changes – growth factors.

A heloma molle is localised thickening of epidermis due to excessive intermittent pressure and friction, meeting with constant resistance occurring over a bony prominence. This type of corn is found interdigitally. Causes include footwear – heavily plays a part in the development of interdigital corns. Digital and metatarsal formulae – can be congenital/ acquired. Lesser toe deformities. Congenital deformity. Muscle imbalance. Over pronation. Splayed forefoot.

Clinical signs - Macerated hard corn – soft and soggy due to accumulation and evaporation of sweat from between toes; white in appearance. Ring shaped – determined by moulding of the skin between the 2 bony prominences. Shallow nuclei. May be inflamed and irritable. Skin may be papery.

	Created by Morgan Morgan about 10 years ago

University Pod Year 1 Note on Hard and Soft corns, created by Morgan Morgan on 04/05/2014.

Hard and Soft corns