Aplasia Cutis Congenita: Trichoscopy Findings.

Aplasia cutis congenita (ACC) is a rare disorder characterized by localized absence of skin that most commonly affects the scalp. We present a case of ACC in a 45-day-old girl and the dermoscopic findings. Dermoscopy has shown to be an easy, fast and useful method for the diagnosis of this condition.

INTRODUCTION

Aplasia cutis congenita (ACC), also known as congenital absence of skin, is a group of disorders characterized by the absence of a skin fragment at birth.[12] Its incidence is estimated at 1–3 cases in 10,000 births.[3] The first case was reported by Cordon in 1767, who described a lesion located on the upper limb of a child.[4]

CASE REPORT

A 45-day-old girl had a patch of alopecia, present since birth. Clinical examination showed a hypopigmented plaque, with alopecia in the left frontoparietal region. Trichoscopy revealed hair bulbs, visible through the semitranslucent epidermis, and a vascular network. No other manifestation or association was detected through clinical examination [Figure 1].

Figure 1

(a) Arrow indicating the location of the hypopigmented plaque; (b) dermoscopy × 20 magnification: translucent appearance of the epidermis, visible hair bulbs, lack of skin appendages, hair roots in the peripheral area and vessels

DISCUSSION

Hair loss is a frequent complaint in children, and the most common causes are tinea capitis, alopecia areata, telogen effluvium, and trichotillomania. Furthermore, uncommon causes include atopic dermatitis, folliculitis decalvans, congenital ichthyosis, nevus sebaceous, and ACC.[5]

The absence of skin in ACC varies in depth. It can affect the epidermis and upper dermis, with minimal alopecic scarring; but it can likewise extend to deep dermis, to subcutaneous tissue or even to the periosteum, the skull, and the dura. Most lesions occur on the scalp vertex laterally to the midline. Generally, it is a solitary lesion, despite the possibility of multiple lesions and even symmetrical presentation.[12] Frieden proposed a classification system for ACC based on the number and location of the lesions and the presence or absence of associated malformations.[1]

The diagnosis is usually established by clinical examination. A biopsy is rarely needed to elucidate the case. Histological examination of ACC shows a thin layer of dermal collagen without overlying epithelium or adnexal structures.[6] Imaging studies are recommended for atypical or very large scalp defects, to evaluate possible underlying bone, vascular, or soft tissue defects. Other conditions can have a similar presentation, such as nevus sebaceous, herpes simplex, epidermolysis bullosa, and trauma.[7] If there is a pattern of findings suggesting a genetic disorder, chromosome analysis may be carried out.

Recently, trichoscopy has gained importance for the diagnosis of both melanocytic and nonmelanocytic lesions. Nonetheless, few reports have evaluated its use in ACC. Rakowska et al. described a radial arrangement of hair shafts, visible elongated hair bulbs with darkly pigmented proximal ends through the semitranslucent epidermis, prominent vessels which correlate with skin atrophy and no follicular openings at the center of the lesion.[8] Trichoscopy is useful to distinguish ACC from sebaceous nevus in newborns.[9] Neri et al. have compared trichoscopy aspects of sebaceous nevus and ACC to help in the differential diagnosis: While ACC shows a complete lack of skin appendages and a translucent appearance, sebaceous nevus shows sebaceous gland not associated with hair follicles.[910]

CONCLUSION

We describe a case of ACC and its trichoscopy findings. These findings indicate that the diagnosis of ACC can be carried out easily and promptly using trichoscopy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.