The estimated annual incidence of morphea is 3.4-27 cases per 1 000 000. There is a bimodal peak of onset: 7 and 11 years for pediatric-onset disease and 44 and 47 years for adult-onset disease. Women are affected more frequently than men (2.4-5:1). Up to 20% of patients with morphea have extracutaneous disease or concomitant autoimmune disease such as psoriasis, vitiligo, inflammatory bowel disease, diabetes mellitus, and thyroiditis.
Morphea can be divided into several clinical subtypes, including circumscribed or plaque type, linear (including en coup de sabre and Parry-Romberg syndrome), generalized, and less common variants such as bullous, pansclerotic, and mixed morphea. Eosinophilic fasciitis, also known as Shulman syndrome, is often considered a part of the clinical spectrum of morphea.
In circumscribed or plaque-type morphea, classic lesions of morphea are round or oval erythematous to violaceous plaques. As lesions progress, sclerosis occurs at the center of the lesions, leading to an indurated, yellow-white, waxy center with an erythematous to violaceous border, resembling a "lilac halo." Lesions are usually asymmetric and can be associated with alopecia and decreased sweat production. Concomitant genital lichen sclerosus may be present in up to 40% of patients with plaque-type morphea.
In the linear subtype, there is band-like cutaneous sclerosis that is usually unilateral and can cause contractures and limb-length discrepancies in up to 10% of patients. En coup de sabre is a specific subtype of linear morphea that affects the paramedian forehead and scalp, and it can be accompanied by alopecia as well as ocular, neurological, and odontostomatologic complications. Progressive facial hemiatrophy, also known as Parry-Romberg syndrome, is characterized by minimal cutaneous changes with significant unilateral atrophy of the underlying tissue of the face, often with underlying abnormalities and increased risk of seizures.
Generalized morphea is a rare variant that is defined as more than 4 plaques larger than 3 cm and/or involving 2 or more body sites. Individuals with this variant are more likely to have systemic symptoms including myalgias, arthralgias, and fatigue. This variant may be difficult to distinguish from scleroderma.
Pansclerotic morphea is a debilitating variant that affects subcutaneous tissues and even bone. There is associated muscle atrophy, joint contractures, and nonhealing ulcers.
- Joint mobility and impairment of muscle growth – in linear or deep morphea crossing joint lines
- Ocular or oral complications – in craniofacial morphea
- Carpal tunnel syndrome – in morphea at the wrist
- Chronic ulcers or squamous cell carcinoma – in pansclerotic morphea
In children, morphea is observed in a 2-3:1 female-male ratio, with the mean age of onset ranging from 7-10 years. The most common subtype in childhood-onset morphea is linear morphea, which includes limb or trunk involvement, en coup de sabre, and progressive facial hemiatrophy, followed by the plaque variant.
The etiology currently is unknown, although potential exogenous triggers have been suggested, including infection with varicella zoster virus (VZV), Borrelia burgdorferi, or Epstein-Barr virus (EBV), local trauma, sunburn, surgery, and BCG vaccinations for tuberculosis.