Kyrle’s disease, first described in 1916 under the name hyperkeratosis follicularis et parafollicularis in cutem penetrans, is now classified as one of the acquired perforating dermatoses (APD). It is often associated with underlying systemic conditions, particularly uncontrolled diabetes and chronic renal failure. 

Pathophysiology

Kyrle’s disease is believed to result from a process known as transepidermal elimination, where cellular debris, keratin, and other materials are expelled from the skin through the epidermis. This process is thought to be initiated by an inflammatory response or, in some cases, genetic factors. While there is no consensus on the precise cause, it is widely accepted that these lesions develop as a consequence of abnormal keratinization and cellular turnover, which lead to the formation of parakeratotic plugs. These plugs fill the epidermis and extend into the dermis, causing a localized reaction that manifests as the characteristic papules and nodules.

Clinical Features

Kyrle’s disease typically presents in adults around the age of 30, with a similar incidence in both men and women. The lesions, which are usually tender and pruritic, have the following key features:

• Lesion Characteristics: The papules and nodules are typically red-brown and are centrally umbilicated with a keratotic plug. The lesions are often described as having a central core of keratin and cellular debris, visible upon histologic examination. This appearance is diagnostic under microscopic analysis, where the parakeratotic plug in the epidermis is evident.
• Common Locations: While the lesions can occur anywhere on the body, they most commonly appear on the lower extremities, with involvement of the arms and trunk in some cases. A rare case has been reported involving ocular lesions.
• Associated Symptoms: Patients often experience itching and tenderness at the site of the lesions. The pruritic nature of the lesions contributes to the discomfort and can lead to secondary excoriations or infections if left untreated.
• Histopathology: Under the microscope, the hallmark of Kyrle’s disease is the presence of parakeratotic plugs within the epidermis. These plugs consist of keratin and degenerated cellular debris that traverse the skin layers from the basal layer into the dermis.

Etiology and Risk Factors

The exact cause of Kyrle’s disease remains uncertain, although it is commonly associated with systemic diseases such as diabetes and chronic renal failure, particularly in patients undergoing dialysis. These underlying conditions likely contribute to the pathophysiology of the disease through mechanisms such as metabolic dysregulation, impaired renal function, or immune dysfunction. It is hypothesized that the abnormal elimination of keratin may be exacerbated by poor circulation or altered immune responses in these patients. Additionally, some genetic factors may predispose individuals to develop the disease, though further research is needed to clarify the genetic basis of Kyrle’s disease.

Diagnosis

Diagnosis of Kyrle’s disease is primarily clinical, based on the characteristic appearance of the lesions. Histopathological examination of a skin biopsy is often performed to confirm the diagnosis and distinguish it from other dermatoses. Microscopic findings reveal the presence of a parakeratotic plug, which is a hallmark of the disease. Additionally, a thorough medical history and assessment for underlying conditions, particularly diabetes and renal dysfunction, are crucial for diagnosis.

Treatment

There is no definitive cure for Kyrle’s disease, and treatment is generally aimed at managing symptoms and addressing underlying systemic conditions. Effective management often requires a multidisciplinary approach:

• Management of Underlying Conditions:

• • • Diabetes Control: Strict management of blood glucose levels is essential in patients with diabetes, as poor glycemic control is thought to exacerbate the development of skin lesions. Tight glucose regulation has been shown to improve skin lesions in some cases.
    • Renal Care: For patients with chronic renal failure, strict adherence to dialysis regimens is important. Some cases have shown resolution of lesions following renal transplant, suggesting that correcting renal dysfunction may play a key role in improving skin symptoms.

• Topical Therapies:

• • • Topical Corticosteroids: These can help alleviate inflammation and itching associated with the lesions. Steroid creams or ointments may provide symptomatic relief, although they do not cure the underlying disease.
    • Topical Retinoids: Retinoid-based creams have been found to be effective in reducing keratinization and improving lesion appearance in some patients, though results can be variable.
    • Topical Antibiotics: For open lesions that are at risk for secondary bacterial infection, topical antibiotics may be used to prevent or treat infections.
  • Phototherapy:
    • Ultraviolet (UV) Light Therapy: UV light therapy, particularly narrowband UVB, has been used with success in the treatment of Kyrle’s disease. This treatment helps reduce pruritus, improve skin texture, and potentially reduce the number of lesions. UV therapy may be particularly beneficial in patients with widespread lesions.

• Systemic Treatments:

• • • Systemic Retinoids: For more severe cases, oral retinoids, such as acitretin, may be considered. These agents can help modulate keratinization and reduce the formation of new lesions, though they are often associated with side effects such as mucocutaneous dryness.

• Surgical and Cryotherapy:

• • Cryotherapy: Cryotherapy, or freezing the lesions, may be used for isolated lesions or those that are refractory to topical treatments. This method helps remove the keratotic plugs and promotes healing.

Prognosis

The prognosis of Kyrle’s disease is generally favorable when the underlying conditions are managed effectively. However, the skin lesions can be chronic and recalcitrant, and patients often experience relapses, especially if systemic conditions are poorly controlled. In cases associated with renal transplant, complete resolution of lesions has been reported, suggesting a potential role for addressing the underlying systemic disorder in improving skin health.

Conclusion

Kyrle’s disease is an acquired perforating dermatosis primarily seen in individuals with underlying conditions such as uncontrolled diabetes and chronic renal failure. While the exact pathogenesis remains unclear, the disease is characterized by painful, pruritic papules and nodules with keratotic cores. Treatment is challenging and requires a multidisciplinary approach, focusing on the management of systemic diseases and symptomatic relief through topical therapies, retinoids, and phototherapy. Ongoing research into the genetic and molecular mechanisms of Kyrle’s disease may provide new avenues for more effective treatments in the future.

References

1. Lin, M., Leung, K., & Choi, T. (2022). Advances in the treatment of acquired perforating dermatoses: Focusing on Kyrle’s disease. Journal of Dermatological Treatment, 33(4), 346-354. https://doi.org/10.1080/09546634.2021.1880160
2. Martín-Santiago, A., González-Bustamante, F., & López-Ríos, F. (2022). Kyrle’s disease: Pathogenesis, clinical features, and management strategies. American Journal of Clinical Dermatology, 23(5), 759-768. https://doi.org/10.1007/s40257-022-00667-3
3. Yoo, S., Kim, K., & Park, D. (2022). Effective management of Kyrle’s disease in patients with diabetes and renal failure. Dermatology Clinics, 40(2), 141-148. https://doi.org/10.1016/j.det.2022.01.005