UNASSIGNED: Membranous aplasia cutis congenita (MACC) is the most common clinical subtype of aplasia cutis congenita (ACC). It is typified by a localized skin lesion devoid of hair and features a membranous surface. While most MACC individuals do not present with concurrent abnormalities, it can sometimes co-occur with additional physical anomalies and various malformation syndromes. Moreover, the underlying causes of MACC remain elusive.
UNASSIGNED: We describe a case of a 6-month-old female infant diagnosed with MACC. The patient presented with a midline skin lesion on the occipital scalp, characterized by a glistening surface and a hair collar sign. Dermoscopic examination revealed specific features, including translucency, telangiectasia, and hypertrichosis. The infant had a history of patent foramen ovale, and further examination uncovered an asymptomatic ventricular septal defect. Whole exome sequencing revealed 20 gene variants relevant to the clinical phenotype of the patient, suggesting a possible association with MACC.
UNASSIGNED: MACC is a rare and underreported condition, primarily diagnosed based on its distinctive clinical features. It is imperative to emphasize the significance of thorough evaluations in MACC patients, encompassing developmental, cardiac, neurological, and genetic assessments to facilitate early detection and the exclusion of potentially life-threatening comorbidities. Importantly, genetic characterization, as demonstrated in this case, contributes to our understanding of MACC\'s etiology and highlights the need for further research in this field.

We present a rare case of focal facial dermal dysplasia type 4 (FFDD4) in an otherwise healthy boy infant, presenting as bilateral preauricular scarlike defects surrounded by a hair collar, resembling membranous aplasia cutis congenita. The presence of a hair collar supports the hypothesis that FFDD is caused by abnormal closure at facial embryonic fusion lines, but unlike midline scalp defects is not associated with neurological compromise. Other types of FFDD occur at different sites and can be associated with cranial dysgraphism. Awareness of this rare condition by dermatologists is imperative to enable prompt recognition and minimize diagnostic delay.