BACKGROUND: Membranous aplasia cutis congenita (MACC) presents at birth characterized by oval epidermis defect. Skin lesions with MACC have various clinic manifestations. In recent years, the usefulness of trichoscopy (scalp dermoscopy) has been reported for hair loss diseases. However, the dermoscopic features of MACC were mostly reported by case reports.
OBJECTIVE: To summarized the obvious dermoscopic characteristics of MACC.
METHODS: These 56 cases met the clinical diagnostic criteria for MACC without forceps delivery complications or other birth injuries. To find the dermoscopic characteristics of MACC by summarizing 56 infants\' dermoscopic pictures.
RESULTS: The dermoscopic manifestation of MACC are characterized by hair follicle openings and hair deficiency in the center of skin lesions, translucent epidermis, hair root and hair bulb arranged along the margins of skin lesion.
CONCLUSIONS: The typical dermoscopic characteristics of MACC could help clinicians to early diagnose and differential diagnosis.

BACKGROUND: Aplasia cutis congenita (ACC) is a rare congenital condition characterized by the absence of skin layers and sometimes other underlying structures, in a localized or widespread area. The exact etiopathogenesis is not yet completely understood. Membranous ACC (MACC) also described as bullous or cystic ACC is a clinical subtype of ACC, covered with a membranous or glistening surface, and appears as a flat scar. There are less than 20 cases reported in the literature. It has been proposed an abortive form of a defective closure of the neural tube. On the other hand, the trisomy 18 is a chromosomal abnormality characterized by a broad clinical spectrum and the presence of defective closure of the neural tube.
METHODS: We report on an 18-months-old Venezuelan boy, who presented on the parietal scalp a distinctive localized MACC appearing as an oval lesion covered with a membranous surface, characterized by the absence of hairs and the presence of a sharp hair collar. The karyotype in peripheral blood was 47,XY,+ 18.
CONCLUSIONS: This is the second case report of ACC in trisomy 18 and reinforces the interpretation of a non-fortuitous association as well as of a defective closure of the neural tube as pathogenetic mechanism. The case highlights the importance of examining for dermatological alterations such as ACC in cases of chromosomopathy.

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.