Reactive perforating collagenosis

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Definition

Reactive perforating dermatoses are characterized by the transepidermal elimination of dermal connective tissue through the epidermis. 

Reactive perforating collagenosis (RPC) is a form of perforating dermatosis involving the extrusion of altered collagen fibers. RPC can be inherited or acquired, with inherited cases often triggered by trauma or cold exposure. 

The acquired form is more common and frequently associated with systemic conditions such as diabetes mellitus or chronic kidney disease, particularly in patients undergoing dialysis, where pruritus-induced trauma exacerbates the condition.

 

Epidemiology : 

RPC occurs globally without a clear racial predilection. The inherited form is rare and often familial, with onset typically in infancy or early childhood. It may follow either an autosomal dominant or autosomal recessive inheritance pattern. In contrast, the acquired form is more prevalent and usually develops later in life, showing a higher incidence in women with a female-to-male ratio of approximately 3:1. Acquired RPC is strongly associated with chronic systemic illnesses such as diabetes and chronic kidney disease,

 

Etiology

The exact pathogenesis of RPC remains uncertain, but key factors include:

  1. Inherited Form:

 – Linked to genetic abnormalities in collagen structure, leading to focal damage and extrusion through the epidermis.

 – Triggers such as trauma or cold weather often exacerbate the condition.

  1. Acquired Form:

 – Associated with microvascular insufficiency and elevated plasma fibronectin levels, commonly seen in diabetes and chronic kidney disease.

 – Abnormal glycosylation of collagen types I and III in diabetes may alter collagen fibers, contributing to their extrusion.

 – Superficial trauma, scratching, and cold exposure lead to epidermal thinning and necrobiosis in susceptible patients.

 

Clinical Features

RPC typically manifests as a papulonodular mucocutaneous disorder. Lesions appear as red-brown umbilicated papules or nodules with a central keratotic plug and an erythematous halo. The size of the lesions can range from a few millimeters to 10 mm, though rare giant forms measuring up to 10 cm have been reported.

 Lesions are intensely pruritic but are rarely painful or tender. Inherited RPC often affects the hands, elbows, and knees, while the acquired form commonly involves the legs. In both forms, the distribution is generally symmetrical, and lesions may appear more widely scattered or even generalized. A hallmark feature of RPC is the Koebner phenomenon, where new lesions develop in response to trauma or scratching. Lesions typically resolve spontaneously within 6 to 10 weeks, though they may leave post-inflammatory hyperpigmentation or scarring.

 

Diagnosis 

Diagnosis is primarily clinical, based on characteristic lesions and associated systemic conditions.

 – Dermoscopy: May reveal central keratotic plugs and erythematous halos.

 – Skin Biopsy: Multiple biopsies are often required to confirm the histopathological findings, including transepidermal elimination of altered collagen.

 

Management

The management of RPC can be challenging, particularly in the acquired form, as it often involves addressing both the skin lesions and any underlying systemic conditions. Treatment typically focuses on reducing pruritus, minimizing trauma, and promoting lesion healing.

– Topical Treatments:

  • Corticosteroids: Superpotent formulations under occlusion can reduce inflammation.
  • Retinoids: Topical agents like tretinoin may aid in reducing keratotic plugging.
  • Emollients: Improve skin hydration and barrier function.

– Systemic Therapies:

  • Antihistamines: Sedating antihistamines help alleviate itching and improve sleep.
  • Oral Retinoids: Acitretin can reduce lesion severity.
  • Allopurinol: May be considered for refractory cases.

– Procedural Interventions:

  • Intralesional Corticosteroids
  • Cryotherapy or Curettage

– Phototherapy:

  • Broadband or Narrowband UVB: Particularly beneficial for patients with chronic kidney disease, as it can relieve pruritus and improve skin lesions.

– Lifestyle Modifications:

  • Avoid scratching and trauma to the skin to prevent exacerbations. Optimize management of systemic diseases like diabetes and renal dysfunction.

 

 

Written by: 

Raneem Alahmadi, Medical Intern.

Revised by: 

Naif Alshehri, Medical Intern.

Resources:

Bolognia 5th edition

Dermnet