As a podiatry student in the 1980’s I remember my first case of Juvenile Plantar dermatosis in a young girl with painful, cracked soles. I was always interested in dermatology from an early stage in my career and seeing this only fuelled my interest. Over the years, I have seen a few cases, but anecdotally, I think this is an enigmatic skin problem on the decline, as this blog explores.
What is Juvenile Plantar Dermatosis?
Juvenile Plantar Dermatosis (JPD) is one of those skin problems that is difficult to classify into any specific category, making it interesting yet puzzling as far as foot problems go. Like most poorly understood conditions throughout its history it has acquired various names - “Peridigital Dermatosis”, “Glazed Foot” and even “Toxic Sock Syndrome”.
(Image courtesy of PCDS, used with permission)
Clinical Presentation of Juvenile Plantar Dermatosis
The clinical picture for JPD is very characteristic – a child of primary school age presenting with plantar scaling, erythema, fissuring and itching affecting the weight bearing surfaces of the feet including the volar surface of the toes. The foot looks dry and may take on a “glazed” appearance.
The child (male or female) is typically 8-10 years old at onset, but can be from 3-14 years of age, as described in the first reported cases. Typically, mycology is negative for dermatophyte infection in virtually all cases.
The arches, interdigital spaces and dorsa were always free of the eruption but occasionally the heels are involved to. Patients often report a fluctuation in severity with no correlation to seasonality. The typical duration of the condition is around 2 to 7 years [1].
Differential Diagnosis
Diagnosis of JPD is made on clinical grounds alone, when other causes have been ruled out. Common pedal dermatoses which may resemble JPD include contact dermatitis and tinea pedis. Contact dermatitis may resemble JPD but is uncommon in children. If there is any doubt a detailed history should be taken, and patch testing is advisable to identify possible allergens.
The commonest causes of allergic foot dermatitis are rubber, chromates and adhesives [2]. A study from Edinburgh of 41 children with plantar dermatitis [3], of which 14 had a diagnosis of JPD. Of the JPD group, 4 patients also a positive patch test of some kind suggesting that allergy may accompany JPD in small number of cases. Positive patch test results have been observed in one study in 53% of JPD cases [4].
Tinea pedis is probably easier to rule out. Firstly, in JPD the toe webs are generally spared but in tinea they often exhibit maceration or dry fissuring. Secondly, JPD is a markedly symmetrical unlike fungal infections. Furthermore, mycological examination can confirm the presence of fungal elements. Bear in mind, the incidence of fungal foot infection is very low in children under ten years of age [5].
Treatment of JPD
Even though, in virtually all cases, the condition resolves spontaneously around puberty there is currently no one effective treatment. Steroid therapy is generally ineffective - suggesting the condition is not a true eczema.
Most interventions are based on achieving symptomatic relief. As fissuring for most patients is cited as the major symptom, treatment is mainly focused on emollient therapy. Typical regimes include the use of emollient ointments rather than creams as they tend to have a more occlusive effect. However, as they tend to be much stickier, they are best applied at night under occlusion.
Where an allergy is suspected, the patient should be referred for specialist patch testing.
Footwear advice is important to prevent excess sweating and maceration. Footwear changes should be made regularly, and shoes should be natural leather inside and out. Synthetic linings and insoles where possible should be removed and replaced with natural materials. Some patients find relief from using pure cork insoles. Hosiery, like footwear, should be natural fibre only and changed regularly. Other suggested treatments have been avoiding the use of footwear altogether - patients may be advised to go barefoot for as long as possible.
History of Juvenile Plantar Dermatosis
It was named 48 years ago by Professor Rona Mackie, a dermatologist at the western Infirmary in Glasgow [2], who’s 1971 thesis was instrumental in the development of dermoscopy as a clinical tool in recognising melanoma. Her 1976 paper on JPD highlighted the emergence of 102 cases of young children with a dermatitis exclusively affecting the plantar surface of the feet. It was suspected that it was allergic contact dermatitis but upon testing only 13 children had any positive patch tests. A similar figure was found in another study of 250 children with JPD with only 9% showing any positive patch tests [6].
Eczematous type reactions like these are normally associated in patients with a history of atopic disease such as eczema, asthma and other allergies, often with palmar involvement. Only 9 patients in this group were classed as atopic (and had palmar involvement). For patients without atopy, it was predominantly a plantar problem. Prior to this there had been two published reports of a plantar eczema eruption in two cohorts of Scandinavian schoolchildren but many of these were in patients with pre-existing atopic eczema elsewhere which worsened in winter (a feature more in line with eczema) [7, 8].
Aetiology
Historically, the condition has been thought to be a disorder of sweating. This has been based on findings from a number of studies. In most of this work much attention has been paid to the role of occlusive, synthetic footwear and hosiery. Many of these synthetic materials became mass production items in the late 1960’s – coinciding with the emergence of the disorder. Newer synthetic materials used in shoes tend to be more water repellent to prolong their durability. As a consequence, it produces a hot and humid environment for the foot which leads to high humidity and sweat accumulation predisposing to JPD. So how does a sweaty foot become dry and fissured?
Shrank [9] first suggested that excess sweating may be a causative factor in the development of the disease. As the foot becomes more macerated, sweat accumulates in the outer layers of the epidermis and thus weakens normal skin integrity. The normal mechanical shearing forces exceed the capacity of the macerated skin causing displacement of the sweat ducts as they emerge through the stratum corneum effectively blocking them off automatically interrupting sweat release. Schank’s concept would certainly explain why the condition only affects the weight bearing areas of the foot and why it leads to dryness as sweating is effectively abated due to “disconnected” sweat ducts.
It is interesting that Mackie and other researchers have highlighted how patients found their feet deteriorated after periods of vigorous activity such as football or other sports [2, 10, 11]. In addition, in a study of 56 patients with JPD, biopsies consistently highlighted inflammation around the sweat duct apparatus [12-14]. A 2014 study suggested this inflammation was located at the start of the epidermis [14] possibly where most of the mechanical forces are focussed. Moreover, in a later case series of JPD sweat ducts in JPD patients versus controls the sweat duct was observed to be abnormal – with fewer eccrine sweat duct openings [15] consistent with Schrank’s theory.
Schank himself noticed that if a sufferer went barefoot for a period of around 3 weeks significant improvement was observed in their condition - this period he believed coincided with the regeneration of a healthy sweat duct with the restoring epidermis. Authors have advocated bed rest since as helpful treatment for this condition – perhaps working on a similar principle.
Under the microscope the histology of the condition is far from clear. Typically, the skin shows inflammation around the sweat glands as well as sweat duct blockage. Ashton & Griffiths [12] suggested that blockage was a combination of factors including bacterial invasion. In their study they demonstrated that suffers had a higher density of micrococci and staphylococci but this work has never been followed up.
Where have all the cases of Juvenile Plantar Dermatosis gone?
It’s interesting to note that over the last decade references to this condition have decreased and it has not been reported so frequently, even as clinical updates in the medical literature. A quick analysis of the publication data searching in PubMed under JPD show that it first appeared in 1976 (following Mackie’s paper) with a few in the 1980’s but a gradual decline in published papers over the last 20 years with only one published in the last five years on the major medical databases. You'll notice even the references in this article are mostly 30 years old. This may just reflect the fact it is an unusual or that something has changed.
JPD became apparent in the early 1970’s, the reason for this in unknown but it may coincide with the introduction of mass production and plastic into footwear design. Excessive plastic materials can provoke and retain hyperhidrosis weakening the epidermis, according to Shrank’s theory. It could be suggested that as time has progressed, footwear design has gradually improved with newer materials which are breathable and with a design and material construction that prevents the foot becoming too hot. Consequently, increased footwear quality has reduced the prevalence of JPD. Of course, that is purely theoretical, but it may explain the reduction in cases presenting in practice for the last 30 years.
References
1. Jones, S., J. English, and A. Forsyth, Juvenile plantar dermatosis - An 8 year follow-up of of 102 patients. Clinical & Experimental Dermatology, 1987. 12(1): p. 5-7.
2. Mackie, R.M. and S.L. Husain, Juvenile plantar dermatosis: a new entity? Clin Exp Dermatol, 1976. 1(3): p. 253-60.
3. Darling, M.I., et al., Sole dermatitis in children: patch testing revisited. Pediatr Dermatol, 2012. 29(3): p. 254-7.
4. Sivakumar, A., M. Munisamy, and L. Chandrashekar, Is Patch Test Necessary in Children to Solve the Clinical Conundrum of Foot Eczema. Dermatitis, 2022. 33(5): p. 349-354.
5. Philpot, L. and D. Shuttleworth, Dermatophyte onychomycosis in children. Clinical and Experimental Dermatology, 1989. 14: p. 203-205.
6. Ashton, R.E. and W.A. Griffiths, Juvenile Plantar Dermatosis--atopy or footwear? Clin Exp Dermatol, 1986. 11(6): p. 529-34.
7. Möller, H., Atopic winter feet in children. Acta Derm Venereol, 1972. 52(5): p. 401-5.
8. Schultz, H. and H. Zachariae, The Trafuril test in recurrent juvenile eczema of hands and feet. Acta Derm Venereol, 1972. 52(5): p. 398-400.
9. Shrank, A., The aetiology of juvenile plantar dermatosis. Clinical & Experimental Dermatology, 1987. 12(1): p. 5-7.
10. Young, E., Forefoot eczema--further studies and a review, in Clinical and experimental dermatology. 1986, Oxford University Press: England. p. 523-528.
11. Graham, R.M., J.L. Verbov, and C.F. Vickers, Juvenile plantar dermatosis. Clin Exp Dermatol, 1987. 12(6): p. 468-9.
12. Ashton, R., R. Jones, and A. Griffiths, Juvenile plantar dermatosis: a clinicopathologic study. Archives of Dermatology, 1985. 121(2): p. 225-228.
13. van Diggelen, M., E. van Dijk, and R. Hausman, The enigma of juvenile plantar dermatosis. Am J Dermatopathol., 1989. 8(4): p. 336-340.
14. Zagne, V., N.C. Fernandes, and T. Cuzzi, Histopathological Aspects of Juvenile Plantar Dermatosis. The American Journal of Dermatopathology, 2014. 36(4).
15. Ashton, R.E. and W.A. Griffiths, Studies on sweating and bacterial ecology in Juvenile Plantar Dermatosis, in Clinical and experimental dermatology. 1986, Oxford University Press: England. p. 535-542.