Diagnosing And Treating Pigmented Leg Lesions In A Dialysis Patient

A 74-year-old African American male presents with painful, pruritic, hyperkeratotic papules on the extensor aspect of his bilateral legs. The lesions extend from mid-thigh to the dorsum of the foot bilaterally.

The patient states these lesions have been present for two years, right around the time he began dialysis. The patient states that the lesions are painful when palpated but he has not sought treatment for them. His past medical history is significant for end-stage renal disease and heart disease, and a 10-year pack history of smoking cigarettes. He takes medications but cannot recall which ones and did not bring a list to the visit.  
 

Key Questions To Consider

1. What is the most likely diagnosis?
2. What is your differential diagnosis?
3. What are the characteristic lesions in this disease?
4. Which patients are most likely to have these lesions?
5. What is the treatment?

Answering The Key Diagnostic Questions
1. The most likely diagnosis is acquired perforating dermatosis of dialysis, which is a form of acquired perforating dermatosis. Acquired perforating dermatosis describes a group of dermatologic disorders characterized by the presence of large keratotic papules throughout the body. This condition most commonly occurs in patients with diabetes and/or end-stage renal disease patients on dialysis.^1,2
2. The differential diagnoses include prurigo nodularis, folliculitis, keratosis pilaris and keratoacanthoma.
3. The characteristic skin lesions of this disease are pigmented, pruritic dome-shaped papules with central crusts or plugs, which commonly arise on the trunk and extensor limb surfaces of the lower extremity.³
4. This condition occurs most commonly in patients with diabetes mellitus and/or patients with chronic kidney disease/end-stage renal disease who are receiving hemodialysis.⁴
5. Treatment options include topical and systemic retinoids, topical and intradermal steroids and ultraviolet-B (UVB) phototherapy, allopurinol and cryosurgery.

What You Should Know About Acquired Perforating Dermatosis Of Dialysis
Reports of perforating dermatoses associated with renal failure first appeared in dermatologic literature in the early 1980s.⁵ Varying reports have shown that between 5 to 10 percent of all patients undergoing dialysis (both peritoneal and hemodialysis) have clinical findings consistent with acquired perforating dermatosis.¹ Another study showed a majority of these patients had insulin dependent diabetes.⁶ In order to make a definite clinical diagnosis, a skin biopsy is required. A biopsy will typically show crater-like invaginations of the epidermis, which are filled by keratotic plugs and basophilic cellular debris. Giant cells and keratin debris are typically present in adjacent dermis as well.

Clinically, these patients will have an eruption of generally pruritic, cone-shaped, and plugged hyperkeratotic plaques, papules and nodules.⁷ The color of these lesions may vary. They are most commonly black or red with a pale center. The lesions typically present on areas that are predisposed to superficial trauma and friction such as scratching. The lesions typically present on the extensor surfaces of the legs and thighs, but may be present on the arms, chest, head, buttocks and back as well.

Understanding The Differential Diagnoses
Prurigo nodularis is a benign neurodermatitis of unknown etiology characterized by firm, hyperkeratotic, pruritic nodules, most commonly localized symmetrically on the bilateral extensor lower extremities. Chronic skin itching can result in permanent skin changes such as hyperkeratosis, hyperpigmentation and thickened skin. Base the diagnosis upon skin changes, pruritus and a skin biopsy to rule out other diseases.

Folliculitis is an inflammation of hair follicles usually caused by shaving, friction from clothing or an insect bite. This condition may cause the hair follicle to become infected with bacteria such as Staph aureus or P. aeruginosa. These lesions present as small raised pruritic pustules and are most common in the armpit, neck and groin areas. Treatment usually consists of topical antiseptics or antibiotic ointment such as mupirocin or Neosporin.

Keratosis pilaris is an autosomal dominant disorder characterized by non-painful pink or skin-colored keratotic plugs that are usually visible on the outer upper arms, thighs and face. This results from an increase in keratin production by the body and occurs in more than 50 percent of adults worldwide.⁸ The diagnosis is usually clinical and no special tests are needed. Treatment is usually not necessary as it is harmless. However, if the patient desires, he or she may use topical lotions and creams such as urea, lactic acid, salicylic acid and vitamin D.

Keratoacanthoma is a rapidly growing, dome-shaped, flesh-colored lesion, which is surrounded by a smooth wall of inflamed skin with a keratin plug in the center. There is much controversy in the literature as to whether this lesion is malignant or benign as squamous cell carcinoma has been associated with this lesion.⁹ This lesion commonly arises on sun-exposed skin as evidence has shown UV rays to be a possible etiology. In addition to a detailed history and physical, one would confirm the diagnosis with an excisional skin biopsy. Treatment consists of electrocautery and curettage.

How To Treat The Condition
Treatment of acquired perforating dermatosis of dialysis is extremely difficult and authors have suggested various methods of therapy.¹⁰ In general, advise patients against local scratching as it may aggravate the condition. Local keratolytic agents (salicylic acid 12.5%) and topical steroids (clobetasol propionate 0.05%, Clobex, Galderma Laboratories) applied twice daily have been effective. Oral retinoid therapy (acitretin 25 mg daily, Soriatane, Stiefel) and topical retinoid therapy (tazarotene gel 0.1%) have also been effective. Phototherapy (narrow-band or broadband UVB, or psoralen plus UVA) may be helpful for pruritus.

A recent study showed that the well-known anti-gout medication allopurinol was also successful in treating acquired perforating dermatosis of dialysis.¹¹ Although the mechanism of action is unknown, authors have speculated that allopurinol inhibits xanthine oxidase, which decreases oxygen free radicals and therefore causes collagen damage in acquired perforating dermatosis of dialysis.

Dr. Vlahovic is an Associate Professor and J. Stanley and Pearl Landau Fellow at the Temple University School of Podiatric Medicine. She writes a monthly blog for Podiatry Today. Readers can access Dr. Vlahovic’s blog at www.podiatrytoday.com/blogs/556 .
Lion Sassoon is a third-year student at the Temple University School of Podiatric Medicine.

References

1. Morton CA, Henderson IS, Jones MC, Lowe JG. Acquired perforating dermatosis in a British dialysis population. Br J Derm. 1997; 135(5):671-7.
2. Maurice PD. Acquired perforating dermatosis in renal patients. Nephrol Dial Transplant. 1997; 12(12):2774-75.
3. Markova A, Lester J, Wang J, Robinson-Bostom L. Diagnosis of common dermopathis in dialysis patients: a review and update. Seminars Dialysis. 2012; 25(4):408-18.
4. Lynde CB, Pratt MD. Acquired perforating dermatosis: association with diabetes and renal failure. CMAJ. 2009; 181(9):615.
5. Hurwitz RM, Melton ME, Creech FT 3rd. Perforating folliculitis in association with hemodialysis. Am J Dermatopathol. 1982; 4(2):101-8.
6. Khan Y, Swain JP. Acquired reactive perforating collagenosis in an insulin dependent diabetes mellitus patient. J Indian Med Assoc. 2009; 107(11):825-6.
7. Vaidya DC, Schwartz RA. Prurigo nodularis: a benign dermatosis derived from a persistent pruritus. Acta Dermatovenerol Croat. 2008;16(1):38-44.
8. Alai AN. Keratosis pilaris. Medscape. Available at https://emedicine.medscape.com/article/1070651-overview . Published June 19, 2014. Accessed Jan. 13, 2015.
9. Kossard S, Tan KB, Choy C. Keratoacanthoma and infundibulocystic squamous cell carcinoma. Am J Dermatopathol. 2008; 30(2):127–34
10. Tilz H, Becker JC, Legat F, et al. Allopurinol in the treatment of acquired reactive perforating collagenosis. An Bras Dermatol. 2013; 88(1):94-7.
11. Wong J, Phelps R, Levitt J. Treatment of acquired perforating dermatosis with cantharidin. Arch Dermatol. 2012;148(2):160-162.