Acquired Perforating Dermatosis

Etiology

The exact etiology is not well understood, but there appears to be a genetic predisposition in some cases. Many cases occur in association with diabetes mellitus, CRF, and liver disease.

Epidemiology

Both sexes are equally affected. Acquired perforating dermatosis usually occurs during the fifth decade of life.[6] The exact prevalence and incidence of acquired perforating dermatosis are unknown. A retrospective study of patients diagnosed with APD between 2002 and 2014 included 33 patients. This estimated incidence was 2.53 cases per 100000 inhabitants per year. While this reported incidence is very low, the authors believed that actual APD occurs more commonly. The disease could potentially be underdiagnosed or misdiagnosed as simple excoriations.[4][7] According to published studies, acquired reactive perforating collagenosis was found to be the most common form, while Kyrle disease and perforating folliculitis were the least frequent types of APD.[6] Previous reports have documented the association of acquired perforating dermatosis with various systemic diseases, especially CRF, diabetes mellitus, or both.[5][8][9] suspected that dialysis treatment plays a key factor in the development of APD in diabetic patients.[9] Other associated disorders rarely reported include hepatic dysfunction, HIV infection, hypothyroidism, hyperparathyroidism, atopic dermatitis, and cancers such as liver carcinoma, pancreas adenocarcinoma, Hodgkin’s disease, and myelodysplastic syndrome.[3][6][9][10]

Pathophysiology

Although the pathogenesis of acquired perforating dermatosis is unclear, many hypotheses exist. Patients with APD often exhibit the Koebner phenomenon, where skin lesions develop at the sites of trauma and are exacerbated by scratching.[5][11] Another postulated theory is that self-induced trauma to the skin damages the epidermis or dermal collagen, which eventually causes the onset of APD.[3][9][11] Moreover, leukocyte infiltration observed in skin lesions secretes interleukin-1, which is a stimulator of the synthesis of metalloproteinases, resulting in degrading the components of the extracellular matrix.[10] Finally, according to some authors, the interplay of microtrauma, altered wound-healing capacities, and tissue hypoxia caused by diabetes and also the microangiopathy and oxidative stress associated with CRF are considered to be the triggers of acquired perforating dermatosis.[11][12]

Histopathology

Skin biopsy is mandatory for the diagnosis of acquired perforating dermatosis. However, the pathological features of this condition are not uniform. They may resemble any of the 4 classic perforating dermatoses, including reactive perforating collagenosis, elastosis perforans serpiginosum, perforating folliculitis, or Kyrle disease. Frequently, more than 1 pattern is observed in the same patient.[9][11] Therefore, many authors prefer to lump all these diagnoses into 1 umbrella term of acquired perforating dermatosis. The histology of APD classically shows epidermal invagination, often involving a dilated hair follicle with a keratotic plug consisting of collagen, keratin, or elastic fibers. The principal diagnosis feature is a central keratotic core overlying a focus of epidermal perforation.[11]

History and Physical

Acquired perforating dermatosis may manifest with several polymorphous skin lesions, such as hyperkeratotic, often umbilicated, millimetric, or larger papules or nodules. Erythematous or non-erythematous lesions can also be found in follicular or non-follicular regions, depending on the APD type.[6] Since pruritus is very frequent, excoriations and crusts are common presenting signs. New skin lesions can emerge due to Koebnerization.[5][6][10] Most skin lesions develop on the extensor surfaces of the lower extremities, but APD can also be present on the trunk, scalp, or any area that the patient may scratch or rub due to pruritis.[4][11] Faver et al proposed diagnostic criteria of acquired reactive perforating collagenosis as follows: onset of the disease after the age of 18 years, the presence of umbilicated nodules or papules with a central adherent plug, and elimination of necrotic collagen tissue within an epithelium-lined crater.[8]

Evaluation

Diagnosis of acquired perforating dermatosis relies on the patient’s history, the clinical presentation of the lesions, and especially histopathology with recognition of classic histological features. Dermatoscopic findings during APD show bright white clouds and structureless grey areas, which may be useful in distinguishing APD from prurigo nodularis.[4] However, multiple biopsies are still the recommended procedure before establishing a definitive diagnosis. Estimating blood glucose levels and hepatic and renal function is highly recommended to identify the underlying disease.

Treatment / Management

No controlled studies or guidelines exist for the treatment of acquired perforating dermatosis. All proposed treatments have their basis in previously published case reports or small series. The goal of treatment should include the management of the underlying disease and the relief of pruritus.[6][13] First-line treatment strategies include systemic or topical corticosteroids, retinoids, and keratolytic agents such as urea or salicylic acid. Emollients and oral antihistamines are frequently prescribed to relieve pruritus.[13] Nevertheless, other treatment options are often needed, and there are reports of successful outcomes with tetracyclines, retinoids, phototherapy, and allopurinol.[6][14] Tetracyclines have anti-inflammatory properties and are potent inhibitors of matrix metalloproteinases.[15] Retinoids are prescribed to stabilize keratinocytes and protect collagen from focal damage and epidermal necrolysis.[6] Allopurinol may disrupt collagen glycation by inhibiting xanthine oxidase through its antioxidant effects.[6][14] Phototherapy in NB-UVB and PUVA has improved the management of pruritus and skin lesions.[14] Finally, combination treatment, rather than monotherapy, may be more successful.(A1)

Differential Diagnosis

Differential diagnosis for acquired performing dermatosis includes:

• Folliculitis
• Prurigo nodularis
• Arthropod bites
• Porokeratosis
• Scabies
• Keratosis pilaris
• Excoriated dermal diseases (such as lichen planus and granuloma annulare)
• Multiple keratoacanthomata
• Hyperkeratosis lenticularis perstans
• Perforating pseudoxanthoma elasticum [1][6][10]

Prognosis

After treatment, skin lesions may disappear altogether, leaving atrophic scars or hyperpigmentation. There are only rare reports of spontaneous resolution.[6][14]

Complications

The most common complication in acquired perforating dermatosis is the secondary infection of the lesions.[10]