Acquired Reactive Perforating Collagenosis - A Rare Cutaneous Manifestation of Anti-MDA5 Dermatomyositis.

Sir,

A 51-year-old woman was referred to our clinic for evaluation of a 4-month history of skin lesions of the face and upper extremities as well as ulcers on the lower extremities. She presented with progressive worsening dyspnoea and dry cough 5 months ago and was diagnosed with interstitial lung disease (ILD). She also had night fever, anorexia and significant weight loss. Physical examination revealed mid-facial erythematous patches and multiple ulcers with central serosanguinous crust at the dorsum aspect of the right hand [Figure 1a], right elbow [Figure 1b] and posterior right thigh. Her proximal muscles power was reduced. Her myositis-specific antibodies results revealed strongly positive anti-MDA5. Other relevant investigation results such as CK, LDH, ANA, anti-dsDNA and ENA were not significant. Skin biopsy of the ulcer at the right arm showed degenerated basophilic collagen with vertically orientated collagen fibres that traversed the epidermis, neutrophil infiltration with endothelial damage of the medium size vessel and mucin deposition [Figure 2a and b]. Her electromyography test showed increased insertional activity, complex repetitive discharges and positive sharp waves at left deltoid. A final diagnosis of anti-MDA5 dermatomyositis was made.

Figure 1

Multiple well demarcated punched-out round ulcers with violaceous border and central serosanguinous crust on: (a) dorsal aspect of right hand (b) right elbow

Figure 2

Broadened dermal ridge containing degenerate basophilic collagen, parakeratotic debris and inflammatory cells, haematoxylin & eosin. (a) Magnification x 40 (b) Magnification × 100

Patients with anti-MDA5 antibodies are more likely to have amyopathic DM associated with distinct systemic manifestations, including rapidly progressive interstitial lung disease (ILD), symmetrical polyarthritis and characteristic cutaneous phenotypes such as skin ulceration, tender palmar papules, oral ulcers and diffuse alopecia.[1] Cutaneous ulcers are often found on extensor surfaces of joints, digital pulps, periungual areas and sun-exposed areas. Factors contributing to the development of ulcers in DM are vasculopathy, vasculitis, interface dermatitis and pruritus.[2]

Acquired reactive perforating collagenosis (ARPC) is a chronic disease characterised by a pruritic hyperkeratotic papulonodular rash with transepidermal elimination of dermal components, including collagen, elastic tissue and keratin. The possible mechanism of ARPC involves an imbalance of the reparative process of altered extracellular matrix and oxygen supply in microangiopathy associated with superficial trauma such as scratching.[3] ARPC is usually associated with diabetes mellitus, chronic renal failure and haemodialysis. It may also represent a paraneoplastic phenomenon.

The association between ARPC and dermatomyositis is not established. Transforming growth factor (TGF)-β is a multifunctional protein that is involved in tissue repair and extracellular matrix (ECM) reorganization. Overexpression of TGF-β3 is associated with transepidermal elimination in ARPC.[4] After muscle injury, TGF-β1 gets involved in muscle repair by regulating ECM. However, overproduction of TGF-β1 induces excessive ECM deposition and fibrosis, eventually leading to incomplete muscle recovery and myopathy.[5]

Anti-MDA-5 DM with ILD is resistant to conventional immunosuppressive therapy and significantly associated with poor survival. Treatment with intravenous immunoglobulin (IVIg) in DM had been successful with clinical and histological improvement as well as reduction of endomysial inflammation. The downregulation of TGF-β1 following IVIg therapy suggests that excessive TGF-β1 contributes to the accumulation of ECM and chronic inflammatory response.[6]

Thus, the authors wish to highlight that ARPC may be one of the cutaneous manifestations of anti-MDA5-associated DM. Further studies are needed to confirm the role of TGF-β and will greatly add value to this relationship.

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Conflicts of interest

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