Practice Essentials
Reactive perforating collagenosis is a rare skin disorder characterized by the transepidermal elimination of altered collagen through the epidermis. The 2 distinct forms of are an inherited form that manifests in childhood and an acquired sporadic form that occurs in adulthood.
The lesions of reactive perforating collagenosis are intensely itchy, leaving some scarring after resolution. These lesions often occur on a background of very itchy skin.
The inherited form of reactive perforating collagenosis is not associated with any systemic complications. The acquired form of reactive perforating collagenosis occurs in patients with multiple medical problems, but whether the development of the lesions implies a poorer prognosis is unclear. Many patients with the acquired form have diabetes mellitus or renal failure.
The 4 primary perforating diseases are reactive perforating collagenosis, elastosis perforans serpiginosum, Kyrle disease, and perforating folliculitis, although whether perforating folliculitis is a primary perforating disease has been questioned, given that ruptured follicles are a feature of many infective conditions.
Some authors reserve the term reactive perforating collagenosis for the rare inherited form of the disease, preferring the term acquired perforating dermatosis for the acquired form. This article describes both inherited reactive perforating collagenosis and acquired reactive perforating collagenosis.
Flesh-colored, umbilicated, dome-shaped papules or nodules as large as 10 mm in diameter are typical. Lesions are most commonly found on the extensor surfaces of the limbs and the dorsa of the hands.
Urea and creatinine determinations are needed to detect any underlying renal impairment.
Histologically, early lesions show epidermal hyperplasia and established lesions show a cup-shaped depression of the epidermis.
Lesions tend to be self-healing but recurrent. Topical steroids are usually not helpful, but intralesional steroids have been successful. [1]
Pathophysiology
The major abnormality in reactive perforating collagenosis is focal damage to collagen and the elimination of the disrupted collagen through the epidermis. [2] Superficial trauma (eg, scratching) may contribute to the etiology of reactive perforating collagenosis, and reactive perforating collagenosis is frequently associated with pruritus. For example, a 58-year-old woman was diagnosed with acquired reactive perforating collagenosis manifesting on the bilateral lower extremities secondary to minor depilatory trauma. [3] Cold may precipitate the lesions, especially in the inherited form.
The acquired form usually occurs in patients with diabetes or chronic renal failure, especially those receiving dialysis. Other associations with systemic diseases, such as malignancy, have been reported.
Faver et al proposed diagnostic criteria for the adult (acquired) form of reactive perforating collagenosis, as follows [4] :
-
Elimination of necrotic basophilic collagen bundles into a cup-shaped epidermal depression as seen in biopsy specimens
-
Umbilicated papules or nodules with a central, adherent keratotic plug
-
Onset of lesions after age 18 years
Epidemiology
Inherited reactive perforating collagenosis is a rare disorder. The acquired form of reactive perforating collagenosis is more common, occurring in as many as 10% of patients receiving maintenance hemodialysis. [5, 6]
No racial variations in the incidence of reactive perforating collagenosis are reported, and the sexual incidence of reactive perforating collagenosis is equal. The inherited form of reactive perforating collagenosis usually presents in infancy or early childhood, but the acquired form of reactive perforating collagenosis occurs in adults. In a series of 22 patients with acquired reactive perforating collagenosis, the mean patient age at presentation was 56 years. [4]
-
Typical keratotic papules.
-
Cup-shaped invagination of the epidermis associated with a keratin plug containing inflammatory debris and collagen fibers.
-
Vertically orientated collagen fibers are extruded into the overlying keratin plug.
-
An elastic van Gieson stain demonstrating the expulsion of collagen fibers (red) into the overlying keratin plug.
