Kyrle disease is a rare skin condition classified as a subtype of acquired perforating dermatosis, along with reactive perforating collagenosis, elastosis perforans serpinginosa, and perforating folliculitis. It was first described in 1916 by Austrian pathologist and dermatologist Josef Kyrle in a diabetic woman with generalized hyperkeratotic papules and was originally coined “hyperkeratosis follicularis et parafollicularis in cutem penetrams. “Due to significant clinical overlap, follicular and non-follicular morphology, and variations in histology with differing disease stages, acquired perforating dermatosis was proposed as an umbrella term for all adult-onset perforating disorders. However, there is controversy in the literature as to the classification of Kyrle disease. While some authors use Kyrle disease interchangeably with acquired perforating dermatosis, others define it as a variant of prurigo nodularis that represents end-stage excoriated folliculitis.
Kyrle disease most commonly manifests as multiple, discrete, eruptive papules with a central keratotic plug on the lower extremities. On histopathology, there is a characteristic transepidermal elimination of abnormal keratin. The exact etiology of Kyrle disease has not been elucidated. The majority of case reports suggest it occurs secondary to chronic systemic diseases, most commonly renal failure (stages 4 and 5) and diabetes mellitus. Meanwhile, evidence of Kyrle disease as a primary perforating disorder has been seen in small case reports that show a genetic predisposition. Treatment can be difficult and typically focuses on the management of underlying medical conditions. Keratolytic agents are also recommended as first-line therapy.
To date, there are no well-designed randomized control trials studying treatment therapies for Kyrle disease. Treatment recommendations are currently based on anecdotal reports or small case series. Keratolytics such as salicylic acid or urea are considered first-line therapy. Emollients and oral antihistamines have been used to relieve pruritus. Electrocautery, cryotherapy, CO2 laser, topical retinoids, isotretinoin, and psoralen plus ultraviolet A radiation are alternative therapies. Oral clindamycin 300 mg three 3 a day for one month has also shown beneficial results. Discontinuation of these therapies often results in the recurrence of skin lesions, although there have been reports of complete regression after renal transplantation in dialysis patients. Surgical excision is reserved for severe, refractory cases.