What is Morphea (Localized Scleroderma)
Morphea, also called localized scleroderma, is a chronic autoimmune fibrosing disorder that causes skin thickening and hardening due to excessive collagen deposition, primarily affecting the skin and underlying tissues (subcutaneous fat, fascia, muscle, and bone) but—unlike systemic sclerosis—does not involve internal organs. 1, 2
Disease Classification and Subtypes
Morphea encompasses five distinct clinical subtypes that determine prognosis and treatment approach 1:
- Circumscribed morphea: Limited, superficial plaques that are usually of cosmetic concern only and typically resolve within 3 years 3, 4
- Linear scleroderma: Linear sclerotic plaques that can be severely disfiguring, especially when affecting the face ("en coup de sabre") or extremities, with risk of functional disability 1, 3
- Generalized morphea: Extensive involvement affecting large body surface areas 1
- Pansclerotic morphea: The most severe form involving deep tissues 1
- Mixed subtype: Combination of two or more subtypes 1
Epidemiology
- Morphea is 10 times more prevalent than systemic sclerosis 4
- Juvenile localized scleroderma has an incidence of approximately 3.4 cases per million children per year 5
- Female to male ratio is 2.4:1 with mean age of onset at 7.3 years in children 5
- Adult-onset occurs in about 32% of cases and shows a more aggressive course with increased risk of systemic involvement 6
Clinical Presentation
The disease manifests with characteristic features 3, 5:
- Sclerotic plaques with skin induration and thickening
- Hyperpigmentation or hypopigmentation of affected areas
- Active inflammatory lesions during the disease's active phase
- Alopecia when scalp is involved
- Depressed, fibrotic lesions that can cause significant cosmetic disfigurement
- Deep tissue involvement in morphea profunda affecting dermis, subcutaneous tissue, fascia, and muscle 7
Pathophysiology
The exact pathogenesis remains unknown, but the disease process involves 2:
- Immunologically triggered release of pro-inflammatory cytokines in genetically predisposed individuals
- Profound dysregulation of connective tissue metabolism
- Excessive collagen deposition leading to fibrosis
- No specific serological markers are available for diagnosis 2
Critical Distinction from Systemic Sclerosis
The defining characteristic of morphea is that manifestations are confined to the skin and subdermal tissues and, with rare exceptions, do not affect internal organs—this distinguishes it from systemic sclerosis. 1 Therefore, in the absence of symptoms, examinations to detect systemic involvement are purposeless 4.
Prognosis
- Superficial forms generally have good prognosis and resolve within 3 years 4
- Linear forms, especially in children affecting the face or extremities, can be severe and irreversibly disabling 8
- The significance depends on extent of lesions, potential for functional disability or cosmetic disfigurement, and presence of extracutaneous manifestations 8
Common Pitfall
A critical diagnostic pitfall is mistaking morphea for other conditions such as lichen sclerosus, especially in extragenital sites 3. Skin biopsy from the most active sclerotic area is crucial when diagnostic uncertainty exists or atypical features are present 3.