Dear Editor, Aplasia cutis congenita (ACC) is a rare condition that manifests at birth as an absence of skin in certain areas, partial or complete. In this report, we describe the dermoscopic features observed in a case of membranous ACC (MACC), occurring concomitantly with hypomelanosis of Ito and nevus simplex in an infant. A 4-month-old infant skin of color was born to nonconsanguineous parents, to an elderly primigravida through normal, uncomplicated vaginal delivery, presented with a flat, hairless, grey to bluish scarred plaque with a glistening smooth surface, surrounded by a rim of “tuft of” terminal hairs appearing like a collar Figure 1a. There were asymptomatic, nonprogressive, partially blanchable patches over the occiput and nape since birth Figure 1b. The baby also had a streak of hypopigmented discrete patches bilaterally over the trunk along the line of Blaschko in whorls and streak pattern Figure 1c. Dermoscopy of (Dermlite DL4 dermatoscope–3 Gen, CA, USA–×10 magnification, polarized mode) over scalp showed a bluish translucent background revealing pigmented hair bulbs, visible under the sheath of epidermis with absent central follicular openings, and radially arranged hair bulbs at the periphery Figure 2a with a spot of blood vessel, supporting a diagnosis of membranous aplasia cutis Figure 2b, over the vertex. Dermoscopy of the occiput lesion revealed nonblanchable, linear vessels suggestive of capillary malformation, and dermoscopy over the trunk showed a light brown background with blotchy pigmentation and irregular, cloudy borders suggestive of hypomelanosis of Ito Figure 2c-d.Figure 1: (a) Grey to bluish membrane with glistening smooth surface, surrounded by rim of tuft of terminal hairs (hair collar sign), (b) Nevus simplex over occiput. (c) Depigmented streaks in blaschkoid distribution over trunkFigure 2: (a) Polarized dermoscopy showed hair-collar sign around grey-bluish membrane, (b) bulb of terminal hair as “golf club set” appearance with a spot of blood vessel (red arrow), (c) nonblanchable, linear, branched vessels over the occiput (black arrow), (d) Light brown background with blotchy pigmentation and irregular cloudy borders over the trunk (black arrow) (Dermlite DL4, 3 Gen CA, USA–×10 magnification)ACC is an uncommon and diverse group of congenital disorders marked by localized or widespread absence of skin at birth, most commonly on the scalp. The estimated prevalence of ACC is 5.10/100,000 births.1 MACC, also known as bullous or cystic aplasia cutis, is a clinical subtype of ACC that presents as a cystic or bullous lesion at birth, which eventually transforms into an atrophic, flat scar covered by a thin epithelium. Some cases present with a dark “Collar hair sign,” which can even indicate an underlying neural tube defect (NTD).2 There are fewer than 20 cases reported in the literature.3 Cranial neural tube closure begins around 4 weeks of gestation, with the occipital region closing last. Disruption at this stage may impair subsequent fetal skin development, including melanoblast migration, hair follicle, and capillary formation, which occur later during 7–11 weeks of gestation.4 Fujita et al. reported ACC associated with dermal melanocytosis and nevus flammeus.4 As discussed above, defective closure of the cranial neural tube can interfere with fetal skin development, including processes such as melanoblast migration, hair follicle morphogenesis, and capillary network formation. A similar pathogenic mechanism may have contributed to the clinical presentation in the index case, resulting in capillary malformation of the occipital region and hypopigmented cutaneous lesions over the trunk. Trichoscopy has emerged as a valuable tool for assessing MACC, revealing characteristic patterns like translucent skin with “hair bulbs arranged radially along hair-bearing margins” and “golf club set.”2 The various associations of ACC are explained in Table 1.Table 1: Associations of membranous aplasia cutis congenitaThis case highlights a rare association of MACC with nevus simplex and hypomelanosis of Ito. We also want to emphasize that the dermoscopic signs such as “hair-collar sign” and “Golf club set” are not always associated with NTD. Declaration of consent The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s)/guardian(s) of the patient. In the form, the parent(s)/guardian(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children will not be published, and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Madhumitha et al. (Thu,) studied this question.