[Dermatomyositis with spinulosis (Wong type dermatomyositis). Histologic study. Attempt at pathogenic interpretation]

Area of Science:

• Dermatology
• Pathology
• Rheumatology

Background:

• Dermatomyositis is an idiopathic inflammatory myopathy characterized by muscle weakness and characteristic skin rashes.
• Pityriasis rubra pilaris (PRP) is a rare chronic skin disorder that causes scaling, redness, and small bumps.
• Spinulosis, or keratosis pilaris, is a common follicular keratotic condition.

Observation:

• A pediatric case of dermatomyositis exhibiting generalized spinulosis of the pilose type, mimicking pityriasis rubra (lichen ruber acuminatus), is detailed.
• The spinulosis presented with a distinctive linear verruciform pattern on the dorsal aspects of the hands.
• Histological examination revealed specific lesions associated with the spinulosis.

Findings:

• The observed spinulosis is hypothesized to result from significant degenerative smooth muscle myositis affecting the erector pili muscles.
• This case represents the first reported instance of this specific dermatomyositis-associated spinulosis in a pediatric patient.
• Previous similar cases reported by O'Leary, Christianson, and Wong are referenced.

Implications:

• This case expands the spectrum of cutaneous manifestations associated with dermatomyositis, particularly in pediatric populations.
• Understanding the link between myositis and spinulosis may offer insights into the pathogenesis of both conditions.
• Highlights the importance of considering rare dermatological presentations in the diagnosis of childhood dermatomyositis.