Parry-Romberg Syndrome: Radioclinical Dissociation in a Paucisymptomatic Form and a Proposed Diagnostic Framework.

Background and Clinical Significance: Parry-Romberg syndrome (PRS), also known as progressive hemifacial atrophy, is a rare disorder characterized by progressive unilateral hemifacial atrophy, with potential involvement of the cranial bones and the brain. Although neurological manifestations are frequently described, central nervous system involvement may be subclinical and detectable only through neuroimaging. Owing to its rarity and the lack of standardized diagnostic criteria, most available data derive from case reports and small case series. Case Presentation: We report the case of a 38-year-old female patient diagnosed with PRS (stage 2 according to the Guerrerosantos classification), with onset in childhood characterized by left parietal alopecia, followed by progressive left-sided hemifacial atrophy and a linear "en coup de sabre" lesion. Neurological examination was normal, with no history of seizures or focal deficits. Brain MRI revealed ipsilateral cutaneous, subcutaneous, muscular, and osseous atrophy, as well as atrophy of the left parotid and submandibular glands. Additionally, subcortical white matter lesions were identified in the left frontal lobe in the absence of hemispheric cerebral atrophy. Conclusions: This case highlights a significant radioclinical dissociation, demonstrating that central nervous system involvement may occur even in clinically stable and paucisymptomatic forms of PRS. This disease may be associated with subclinical intracranial abnormalities, underscoring the need for systematic neuroimaging evaluation even in the absence of neurological manifestations. Based on the available literature and the specific features of the present case, we propose a practical clinical framework and imaging algorithm to facilitate early diagnosis and to contribute to the standardization of the diagnostic approach in this rare disorder.