Are Parry-Romberg syndrome and localized craniofacial scleroderma congenital conditions rooted in changes beginning from embryological development?

Parry-Romberg Syndrome and Localized Craniofacial Scleroderma: Embryological Origins

Parry-Romberg syndrome and localized craniofacial scleroderma are not congenital conditions rooted in embryological development, but rather acquired disorders that typically begin in childhood or young adulthood with progressive facial atrophy.

Disease Characteristics and Onset

• Parry-Romberg syndrome (PRS) is a rare neurocutaneous and craniofacial disorder characterized by progressive hemifacial wasting and atrophy that predominantly affects children and young adults, with an estimated prevalence of 1 in 700,000 individuals 1
• PRS typically begins in childhood (not congenitally) and involves progressive dystrophy or loss of subcutaneous tissue in one half of the face 2
• The clinical presentation involves progressive facial atrophy affecting subcutaneous tissues, muscles, and bones that develops after birth, not during embryological development 1
• Localized craniofacial scleroderma (including en coup de sabre) is considered interrelated with PRS, with both having similar clinicopathological appearances that develop postnatally 3

Pathophysiology and Etiology

• The exact etiology of PRS remains unknown, although autoimmune, genetic, and vascular factors are likely contributors - not embryological defects 1
• Immune-mediated processes and disturbed central regulation leading to hyperactivity of the sympathetic nervous system are primarily considered in the pathogenesis 3
• Unlike true congenital conditions like DiGeorge syndrome or CHARGE syndrome which result from aberrant embryological development of pharyngeal pouches and other structures 4, PRS develops after birth
• Congenital conditions with craniofacial involvement (like DiGeorge syndrome) are characterized by defects present at birth due to abnormal embryological development, whereas PRS manifests as progressive atrophy beginning in childhood 4

Clinical Progression and Manifestations

• PRS is characterized by slowly progressive atrophy that typically begins in childhood and continues with skin changes, not present at birth 2
• The disease typically manifests with unilateral facial atrophy that progresses over time, affecting one side of the face 1
• Neuroimaging findings in pediatric PRS are often supratentorial, stable, unilateral, and ipsilateral to skin findings, and can sometimes precede cutaneous manifestations 5
• Ophthalmological manifestations include periocular disorders (enophthalmos, eyelid alterations), ocular disorders (corneal and retinal changes), and neuro-ophthalmological disorders (optic nerve, ocular motor dysfunction) that develop progressively 6

Distinguishing from True Congenital Conditions

• Unlike congenital conditions such as hemifacial microsomia (which is present at birth with an incidence of 1 in 5,600 to 1 in 26,550 live births), PRS develops postnatally 7
• True congenital conditions like DiGeorge syndrome result from defects in embryological development of structures like the thymus and parathyroid glands 4
• Congenital disorders like cardio-facio-cutaneous syndrome begin in the prenatal period with ultrasound findings such as increased nuchal lucency and sometimes cystic hygroma 4
• PRS does not show prenatal manifestations that would be expected in truly congenital conditions 1, 2

In summary, while Parry-Romberg syndrome and localized craniofacial scleroderma have significant impacts on craniofacial structures, they are acquired conditions that begin after birth, typically in childhood, rather than congenital conditions resulting from embryological developmental defects.