Morphea (Localized Scleroderma)

Basics

The term for localized scleroderma is morphea, which is derived from the Greek word for “form” or “structure.” Fibrosis is characteristic and may involve the skin, subcutaneous (SC) fat, cartilage, muscle, and bone.
Morphea must be differentiated from systemic sclerosis, which is a systemic vasculopathy that carries a poorer prognosis. Both are clinical, rather than laboratory diagnoses, because the skin histopathology is identical for both diseases. Clinical hallmarks to differentiate these diagnoses include:
- Progressive systemic sclerosis: begins with symmetric distal acral sclerosis with sclerodactyly, Raynaud phenomenon, dilated nailfold capillary loops with dropout (All are stigmata of vasculopathy.)
- Morphea: spares the distal finger tips and toes but may involve the dorsal hands and feet, absence of Raynaud and abnormal nailfold capillary loops, no true visceral fibrosis
Padua classification for morphea:
- Circumscribed: localized indurated plaques
- Generalized: ≥4 plaques, >3 cm, >2 body sites
- Linear: linear plaques face, scalp, extremity, or trunk
  - Affecting trunk or limbs
  - Affecting head: includes en coup de sabre (epidermal change) and Parry-Romberg syndrome (hemifacial atrophy)—these are thought to exist on a spectrum.
- Pansclerotic: confluent full-thickness sclerodermoid plaques, generally spares the distal fingertips and toes
- Mixed: more than one subtype
- Any subtype can have a deep component.

Linear morphea is the most frequent subtype (~50–65%), followed by circumscribed morphea (~25%), generalized morphea (5–8%), and pansclerotic (1–2%) morphea.
Many patients (15–20%) present with more than one subtype of morphea (mixed morphea).
Localized scleroderma is approximately 10 times more common than systemic sclerosis in childhood. The annual age and sex adjusted incidence is 2.7 cases per 100,000.

Speculated to share common pathophysiology with systemic sclerosis despite differing clinical presentations
Early: T-cell mononuclear cell population, with CD4 > CD8 predominance, and Th1/Th17 activation inducing inflammation with clinical evidence of erythema, induration, and lesional enlargement
Late: T-cell associated cytokines stimulate fibroblasts and endothelial cells to produce transforming growth factor β (TGF-β) and connective tissue growth factor (CTGF), which are main stimulators of tissue fibrosis and increased collagen production. Skewing to immunologic Th2 axis leads to permanent disease damage including late fibrosis and atrophy.

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