Importance of cutaneous findings in childhood scleromyositis in Indian scenario.

Sir,

Scleromyositis is a syndrome combining clinical features of both dermatomyositis and systemic sclerosis (SSc), but differing from both by a chronic and a relatively benign clinical course and association with highly characteristic PM-Scl antibody.[1] There are very few case reports of childhood scleromyositis (CSM) in English literature with only occasional case reports from India. PM-Scl antibody testing is routinely done in all suspected cases of CSM in developed countries, whereas in Indian scenario, PM-Scl antibody testing is costly and not routinely available. Hence, diligent clinical and histopathological examination is cheaper and reliable for the diagnosis of scleromyositis.

A 10-year-old boy presented with increased tightening of skin since 4 monthsand weakness of hip girdle muscles since 1 month. There was history of bluish discoloration of fingers and toes since 5 months. On examination, patient had diffuse binding down of skin over face, forearms, hands, trunk, and lower limbs with relative sparing of neck, flexures, and genitalia. There was diffuse erythema over extensor aspect of upper and lower limbs with prominent facial telangiectasia. Patient had atrophic hypopigmented plaques over proximal interphalangeal joints (PIP) of middle 3 fingers of both hands. Systemic examination was within normal limits. Muscle enzymes were slightly raised. EMG showed presence of myopathic involvement of proximal body muscles. Muscle biopsy showed focal fiber splitting, loss of cross striations, mild vacoulation, and degenerative changes, suggestive of dermatomyositis. Immunological studies showed that ANA was 4+ in 1:100 dilutions in Hep2 cells. Anti scl70 was 99.6 (normal <3). Anti-centromere, anti Jo1, dsDNA, anti-U1-RNP were negative. Skin biopsy from forearm showed unremarkable epidermis, underlying dermis showed homogenization of collagen with paucity of blood vessels [Figure 1]. Picture was suggestive of scleroderma. Skin biopsy from PIP joint showed basal cell vacuolization of epidermis with mild perivascular chronic inflammatory infiltrate and pigment incontinence in upper dermis. Picture was suggestive of dermatomyositis-gottron's papule [Figure 2].

Figure 1

Skin biopsy from forearm showing unremarkable epidermis, underlying dermis show homogenization of collagen with paucity of blood vessels and mild inflammatory infiltrate around ducts of eccrine glands (H and E, ×100)

Figure 2

Skin biopsy from PIP joint showing basal cell vacuolization of epidermis with mild perivascular chronic inflammatory infiltrate and pigment incontinence in upper dermis (H and E, ×400)

Cutaneous features of SSc and dermatomyositis (DM) develop usually within first year of illness and become pronounced during the progression of the disease.[2] A clear recognition of the cutaneous findings is essential for prompt and accurate diagnosis of DM, especially in cases in which cutaneous manifestations are the initial or only findings. Salient features of DM on skin biopsy include vacuolar alteration of the basal cell layer of the epidermis, necrotic keratinocytes and a sparse, superficial, perivascular lymphocytic infiltrate, as seen in our case. These findings are seen in a wide range of clinical DM lesions.[3] Histopathologic findings are not very characteristic in SSc and similar to morphea. At the early stage, mild inflammatory infiltrates are seen around the blood vessels and ducts of the eccrine sweat glands. In the later stage, these infiltrates are reduced or disappeared completely. The vessel walls are thickened hyalinized with homogenization of collagen. Skin biopsies from patients with clinical features of DM and scleroderma, that is, overlap syndrome, show combined histopathological features of DM and scleroderma. Systemic scleroderma associated with myositis is usually a very severe variety of disease, whereas scleromyositis has in general protracted and benign clinical course.[1] Hence, a correct identification of cutaneous findings in scleromyositis in child is prudent and has prognostic and therapeutic implications.