Dermatology MCQ - Inflammatory Dermatoses - Morphoea clinical features and classification

A 7-year-old girl is brought to the clinic by her mother who noticed a large, waxy, ivory-colored plaque on the child's trunk. The plaque has a violaceous border and feels indurated on palpation. The remainder of the skin examination is normal, and the child is otherwise well. This presentation is most characteristic of which subtype of morphoea?

A. Linear Morphoea
B. Pansclerotic Morphoea
C. Generalized Morphoea
D. Plaque Morphoea (Circumscribed Morphoea)
E. Bullous Morphoea

Correct Answer: D. Plaque Morphoea (Circumscribed Morphoea)

Explanation

The description provided is the classic presentation of the most common subtype of morphoea.

• Plaque Morphoea (Circumscribed Morphoea): This form is characterized by one or a few isolated, oval-to-round plaques. They typically exhibit the classic "lilac ring" (a violaceous, inflammatory border) surrounding a sclerotic, ivory-white or waxy, indurated center. The lesions are often asymptomatic and are most commonly found on the trunk. This subtype generally has an excellent prognosis and may soften and resolve spontaneously over years.

Why other options are incorrect

• A. Linear Morphoea: This subtype presents as a linear band of sclerosis, often following the lines of Blaschko. It is most common on an extremity or the frontoparietal scalp and face (en coup de sabre). It is not described as a solitary plaque on the trunk.

• B. Pansclerotic Morphoea: This is a very severe, rare variant characterized by widespread, circumferential involvement of the skin, subcutaneous tissue, muscle, and bone, sparing the fingertips and toes. It is not a solitary plaque.

• C. Generalized Morphoea: This diagnosis requires four or more individual plaques larger than 3 cm in diameter that become confluent and involve at least two out of seven anatomic sites (head/neck, right upper limb, left upper limb, right lower limb, left lower limb, anterior trunk, posterior trunk). A single plaque does not meet this definition.

• E. Bullous Morphoea: This is a rare variant where bullae or vesicles develop on pre-existing sclerotic plaques, often due to severe lymphatic obstruction from the fibrosis. It is not a typical presentation.

Key Associations for Morphoea Clinical Features

• Classification and Subtypes:

  • Plaque-type (Circumscribed): As described above. Includes the "gutate" variant with multiple small (<1 cm) plaques.

  • Linear Morphoea: Can cause significant functional and cosmetic morbidity due to contractures and limb-length discrepancies. En coup de sabre (linear sclerosis on the frontoparietal scalp/forehead) and Parry-Romberg syndrome (progressive hemifacial atrophy) are considered part of the linear morphoea spectrum.

  • Generalized Morphoea: Multiple plaques becoming confluent. Can be disabling but lacks systemic organ involvement.

  • Pansclerotic Morphoea: As above; carries a high risk of contractures and squamous cell carcinoma developing in chronic ulcers.

  • Mixed Morphoea: Combination of two or more of the above subtypes (e.g., linear and plaque), which is common.

• Clinical Course: The disease typically progresses through three phases:

  1. Inflammatory (Edematous): Ill-defined, erythematous or violaceous patches.

  2. Sclerotic (Indurative): Development of the characteristic hard, ivory-white plaques.

  3. Atrophic: The lesions soften, leaving behind hyper- or hypopigmentation and dermal atrophy.

• Extracutaneous Findings: Unlike systemic sclerosis, internal organ involvement is exceedingly rare. However, associated musculoskeletal complications (arthralgias, contractures) are common in linear and generalized forms. There is a strong association with other autoimmune phenomena, and patients should be screened for lichen sclerosus, which frequently co-occurs, especially in the anogenital region.

• Differential Diagnosis: Includes systemic sclerosis (distinguished by Raynaud's, sclerodactyly, and internal organ involvement), eosinophilic fasciitis (peau d'orange appearance, groove sign), scleredema (often post-infection, non-pitting induration of the upper back and neck), and nephrogenic systemic fibrosis.