Aplasia Cutis Congenita: Symptoms, Causes, Diagnosis, and Treatment

Introduction:

Aplasia cutis congenital is a rare form of congenital skin defect. It has a prevalence of approximately one to three incidences out of 10,000 births. There is no considerable gender or cultural predilection. The lesions will typically be detected at birth, although the parents may not take the affected children to the doctor for several months as lesions are often asymptomatic.

What Is Aplasia Cutis Congenita?

Aplasia Cutis Congenita is a rare congenital disorder with a complex inheritance pattern. The affected babies with this disorder are born with a lack of certain layers of skin. It most often affects the scalp but may also involve the trunk, arms, and legs. A thin transparent membrane typically covers the affected areas. This may make the skull and underlying areas visible and cause abnormal development. Aplasia cutis congenita may occur as an isolated entity or associated with other underlying disorders.

What Are the Risk Factors of Aplasia Cutis Congenita?

The factors contributing to aplasia cutis congenital include:

• Aplasia cutis congenita may link with other congenital skin deficiencies such as organoid or epidermal naevi. The familial cases are found to have autosomal dominant and autosomal recessive inheritance.

• Aplasia cutis congenita, which is not associated with syndromes, is associated with a heterozygous mutation of the BMS1 gene on chromosome 10q11.

• It can also occur after placental infection during pregnancy, including varicella, chickenpox, or herpes simplex.

• Teratogens (chemicals or drugs inducing birth deformities, such as methimazole, misoprostol, cocaine, marijuana, carbimazole, and valproic acid) can also cause aplasia cutis congenita.

• Defects during skin development in the womb can also cause aplasia cutis congenita.

• Papyraceous fetus (The death of a twin fetus).

• Early rupture of amniotic membranes.

What Are the Types of Aplasia Cutis Congenita?

A classification for Aplasia cutis congenita is as follows:

Group 1: Scalp aplasia cutis congenita without multiple anomalies.

Group 2: Scalp aplasia cutis congenita with limb anomalies.

Group 3: Scalp aplasia cutis congenita with epidermal and organoid nevi.

Group 4: Aplasia cutis congenita overlapping congenital malformations.

Group 5: Aplasia cutis congenita with associated fetus papyraceous or placental infarct.

Group 6: Aplasia cutis congenita with epidermolysis bullosa.

Group 7: Aplasia cutis congenita present in extremities without blistering.

Group 8: Aplasia cutis congenita caused by specific teratogens.

Group 9: Aplasia cutis congenita associated with malformation syndromes.

What Are the Signs and Symptoms of Aplasia Cutis Congenita?

In 70 to 80 % of cases, aplasia cutis congenita affects the scalp on the lateral sides to the midline. However, the lesions may also appear on the face, trunk, or limbs, occasionally symmetrically.

• The areas of the lesion with skin loss or ulceration may vary in size from 0.5 cm to 10 cm.

• The defects are usually well-demarcated, and it does not contain any inflammation.

• A clump of hair surrounding the aplasia cutis congenita lesion may indicate an underlying neural tube malformation defect.

• Superficial aplasia cutis congenita involves only the upper layers of skin (epidermis). These shallow defects are usually cured before the child's birth, leaving a scar.

• Deeper aplasia cutis congenita defects can spread through all skin layers, subcutaneous tissue, and seldom periosteum, skull, or dura.

• Aplasia cutis congenita may partially heal before birth and seem like an atrophic, membranous, parchment-like, hairless, or fibrotic scar.

• Membranous aplasia cutis congenita is a flat, whitish membrane overlaying the defect on the skull.

• Distorted hair growth, also called the hair collar sign, is characteristic of an underlying cranial defect, including encephalocele, brain tissue outside the skull, and meningocele.

• Aplasia cutis congenita is also reported in a rare bullous variant.

• Some individuals with aplasia cutis congenita also suffer from congenital malformations of the heart, genitourinary (such as gastroschisis or omphalocele), gastrointestinal, and central nervous systems (like meningomyelocele or spinal dysraphism).

How Is Aplasia Cutis Congenita Diagnosed?

History and Physical Examination: The doctor will diagnose aplasia cutis congenita typically solely from clinical examination. Aplasia cutis congenita can have a variable manifestation at birth, including ulceration, membrane-covered defect, erosion, or scar (meaning intrauterine healing). Lesions may vary in size ranging from a few millimeters to several centimeters. Aplasia cutis congenita will slowly become smaller in cases with no underlying deficiencies and form a scarred defect. The lesions that have already healed will exhibit a scar with a thin or flattened epidermis, without adnexal structures, and thick, dermal fibrosis cited on pathology.

Other Tests: Many doctors withhold performing a biopsy of the lesion due to the tender age of the affected child and typical scalp involvement. When a biopsy is essential to aid in the diagnosis, the doctor will suggest a proper workup, including an ultrasound or MRI (magnetic resonance imaging) scan, which is essential to confirm there are no underlying structures that may get damaged during the biopsy procedure.

How Is Aplasia Cutis Congenita Managed?

• The approach to managing individuals with aplasia cutis congenita varies based on the extent and size of the lesions and whether underlying defects are present.

• In case of small lesions with a diameter of less than four cm with no additional defects, the doctor will recommend daily cleansing of the lesion and applying topical antibacterial cream until healing is complete. The lesions will generally heal within a few weeks or months, leaving an atrophic and hairless scar.

• However, larger lesions greater than four cm are typically associated with underlying defects, which increase the risk of complications, such as bleeding, venous thrombosis, and infection. The doctor will advise early surgical repair to avoid these complications in such cases. Lesions of several centimeters in size may require skin grafting or flap techniques to cover the defect.

What Are the Complications Associated With Aplasia Cutis Congenita?

Complications of aplasia cutis congenita rarely occur but may include:

• Secondary wound infection.

• Arterial bleeding.

• Sagittal sinus thrombosis.

• Infection in the brain leads to death.

Conclusion:

Aplasia cutis congenita is a rare condition characterized by the absence of skin in some areas at birth. While its exact reasons remain unclear, various genetic and environmental factors may play a role in its pathogenesis. The condition may manifest in different forms and severity levels, on which its management depends. This usually asymptomatic condition may heal independently, leaving a scar or requiring medical and surgical interventions in more extensive lesions.