Background to this article
It’s always good to receive some interesting cases from colleagues around the UK and beyond, but thanks must go to Dianne (also known as “The Purple Pod”) in Warrington (www.laneendspodiatry.co.uk) for sending this image which sparked off a conversation about an unusual variant of an uncommon condition. Anyway, it’s with Dianne’s permission I have included this as something of a rarity (dermatologically speaking).
Palmoplantar keratoderma (or PPK) is a condition we see quite frequently in podiatry. By definition, it’s a group of various disorders characterised by extensive hyperkeratosis of the palms and soles (which is unrelated to weight bearing). There are many types (at last count over 100) and some have complex sounding names (1). Many are hereditary disorders with affected family members developing the symptoms in childhood. The remainder of cases appear spontaneously (also called “sporadic”) -that is with no prior family history and these are often trickier to diagnose. For many there is no satisfactory cure. For some, oral retinoids prescribed by a dermatologist are the only effective treatment but for many patients these drugs are not suitable. As podiatrists, our debridement skills are often the only way for many patients to gain relief albeit at the cost of our own repetitive strain injury.
Clinical presentation of PPK is highly variable but hyperkeratosis of the soles is always a feature. For a subset of PPK cases they also may be accompanied by a range of other disorders usually affecting the hair, nails, teeth or neurological system. The hyperkeratosis may arise in large discrete areas of callus (focal PPK), or a generalised hyperkeratosis (diffuse). A small number of cases may present peppered with numerous corn-like lesions (punctate PPK). In this blog, a case is presented known as “spiny keratoderma”.
A 78-year-old male and retired lorry driver presented to a podiatry clinic with PPK, which he had been managing himself as he was no longer eligible for NHS podiatry care. A former smoker, he suffered from hypertension, osteoarthrosis and had a previous myocardial infarction subsequently treated with a stent. He also had borderline diabetes. He reported his father had similar foot problems and on examination his skin demonstrated spiny projections of hyperkeratosis from a background of focal areas of PPK on the plantar surfaces.
Figure 1 : Patient Presentation: Spiny Keratoderma
Spiny Keratoderma (SpK) was first described in 1971, by Brown, who described a case of a young naval officer with a PPK, which unusually had keratotic projections (spines) arising from the palmo-plantar surfaces (2). Since then only around 50 cases have been described in the medical literature. Along the way different terminology has been attached to the condition including “music box spine” dermatosis (due to the resemblance of the keratotic spines with the metal pin-studded cylinder of a music box), punctate keratoderma, punctate porokeratotic keratoderma, porokeratosis punctata palmaris et plantaris, palmoplantar filiform hyperkeratosis, minute digitate hyperkeratosis, and spiny keratoderma of the palms and soles (3) Figure 2. The condition appears to affect males twice as often as females.
Figure 2: Close up of keratinous spines
A review of 37 cases in 2017 has given the most insight to date as to the common clinical features of the disorder (4). Patients typically present in their 60’s, and the condition has been observed in all skin types. The condition may range from asymptomatic to painful in sufferers of SpK (5) with some cases being discovered coincidentally. In around a quarter of cases, the condition is limited to just the hand (see figure 3 below).
Figure 3: Spiny Keratoderma limited to the palms in a patient with renal carcinoma (Campbell & Becknall , reproduced under CCL licence)
In around a third of patients, the condition has occurred in patients with previously known and unknown malignancies including cancers of the lung, colon, oesophagus and kidney along with melanoma, lymphoid leukaemia (6) and myeloma. Debate still surrounds the true association between SpK and malignancy. Signs and symptoms which arise with an internal malignancy are termed “paraneoplastic” syndromes and some have argued that this condition may represent such a case, however, others refute this (7) stating that unlike a true paraneoplastic disorder, the spiny keratoderma may precede the malignant disease by many years and continues long after the malignancy may have been resolved – features not consistent with true paraneoplastic syndromes. As a rule, any patient presenting with a recent onset PPK, should be medically assessed to rule out any potential underlying malignancy.
In other patients, non-malignant diseases such as diabetes (8), hyperlipidaemia (5), dariers disease, hypertension, polycystic kidneys (9), renal failure and asthma have been reported but this maybe a random finding as these problems are common in this age group anyway. Similar, many patients with the condition are reported to frequently taking statins and anti-hypertensive drugs.
The cause of the disease remains a mystery but from the literature, two common manifestations are evident. Firstly, an inherited form, which like PPK with a genetic component develops in childhood. The second type develops in older age and many cases have highlighted an association with other systemic diseases. In a few cases, a genetic association has been shown with familial cases arising (10). The condition histologically resembles other forms of PPK, but presents with parakeratosis and columns or stacks of orthostatic keratin which give rise to the spiny appearance (5).
Management of the condition is no different than for other types of PPK, with local and topical treatment being effective for some. One patient reported that he regularly shaves his hands to remove symptomatic lesions (11) whilst topical treatments like salicylic acid and debridement have shown to be helpful to some. Others have required oral retinoids to control the symptoms. For many, podiatry care with regular debridement of plantar lesions is often the only means of obtaining relief of the symptoms.
Spiny keratoma is an uncommon variant of PPK, which for some has a genetic cause but for many the aetiology remains obscure. However, as a precaution, any adult patient presenting with an unexplained hyperkeratosis of the palms and soles should be medically assessed to rule out underlying malignant disease.
The patient (and his podiatrist) has given consent for the inclusion of his case along with the photographs in this article.
1. Stevens HP, Kelsell DP, Bryant SP, Bishop DT, Spurr NK, Weissenbach J, et al. Linkage of an American pedigree with palmoplantar keratoderma and malignancy (palmoplantar ectodermal dysplasia type III) to 17q24. Literature survey and proposed updated classification of the keratodermas. Arch Dermatol. 1996;132(6):640-51.
2. Brown FC. Punctate keratoderma. Arch Dermatol. 1971;104(6):682-3.
3. Gaiser MR, Hausser I, Hassel JC. Spiny keratoderma of the palms and soles – once seen, never forgotten. JDDG: Journal der Deutschen Dermatologischen Gesellschaft. 2017;15(9):939-41.
4. Chee S-N, Ge L, Agar N, Lowe P. Spiny keratoderma: case series and review. Int J Dermatol. 2017;56(9):915-9.
5. Horton SL, Hashimoto K, Toi Y, Miner JE, Mehregan D, Fligiel A, et al. Spiny Keratoderma: A Common Under-Reported Dermatosis. The Journal of Dermatology. 1998;25(6):353-61.
6. Bordel-Gómez M. Palmoplantar spiny keratoderma associated with chronic lymphoid leukaemia. J Eur Acad Dermatol Venereol. 2008;22(12):1507-8.
7. Salmon-Ehr V, Armingaud P, Cambie-Vanderschelden MP, Rault S, Kalis B. Spiny keratoderma. J Am Acad Dermatol. 1997;36(4):656.
8. Nakamura Y, Muto M. Spiny keratoderma of the palms in an insulin-treated diabetic patient. Int J Dermatol. 2013;52(11):1460-1.
9. Anderson D, Cohen DE, Lee HS, Thellman C. Spiny keratoderma in association with autosomal dominant polycystic kidney disease with liver cysts. J Am Acad Dermatol. 1996;34(5 Pt 2):935-6.
10. Campbell EH, Becknell C. Spiny keratoderma exposes underlying renal cell carcinoma. JAAD Case Rep. 2018;4(4):382-3.
11. Torres G, Behshad R, Han A, Castrovinci AJ, Gilliam AC. "I forgot to shave my hands": A case of spiny keratoderma. J Am Acad Dermatol. 2008;58(2):344-8.