*4.1.2.1. Management*

Small sized ACC, located laterally to the median line, is usually a unique congenital anomaly and does not require further evaluation. In sizeable defects, located on the median line, with a membranous appearance that raises the suspicion of a simultaneously damage of the skull and dura mater, cerebral and spinal MRI are recommended. A subjacent neural tube defect must be confirmed or excluded. Treatment for ACC is usually conservative [7].

#### *4.1.2.2. Prognosis*

The outcome is usually very good, small defects evolving toward healing within a few weeks through progressive epithelization and atrophic, hairless scarring [8]. In rare cases, hemorrhage and local infections may appear. Large defects of the scalp can be surgically repaired using autologous or biological grafts.

If aplasia cutis congenita is associated with other anomalies, the outcome depends on their severity.

Deep and small defects of the scalp and skull close spontaneously during the first year of life. Larger-sized defects require surgical correction.

Scalp defects that interest the skull and dura mater can be complicated by sagittal sinus thrombosis and are associated with a mortality rate greater than 50%.

#### *4.1.3. Mild micrognathia*

Micrognathia is a rather frequent clinical craniofacial abnormality, caused by congenital mandibular hypoplasia (**Figure 2**). It is usually associated with a deficient gonial angle, ascending ramus, and mandibular corpus.

**Figure 2.** Mild micrognathia associated with retrognathia.

The pathophysiological mechanism of aplasia cutis congenita is unclear; some theories suggest the involvement of factors such as obstetrical trauma, intrauterine infections with varicella zoster or herpes virus, as well as teratogenic agents, such as cocaine and methimazole [7, 9].

When this anomaly is confirmed, a series of additional investigations are required to determine if there are also other associated malformations that describe a genetic syndrome.

Adams-Oliver's syndrome includes (alongside ACC and limb defects) cutis marmorata telangiectatica congenita, central nervous system abnormalities and cardiovascular abnormalities. To diagnose this genetic syndrome, cerebral and spine (MRI) imaging, limb radiographs, echocardiography and genetic tests with genes ARHGAP31, DOCK6, RBPJ, EOGT [7, 10] sequencing are required. Adams-Oliver Syndrome can be transmitted either autosomal domi-

ACC may evolve with complications (local infection, meningitis, bleeding and superior sagittal sinus thrombosis). The mortality rate lies between 20 and 50% and depends on the size of

Small sized ACC, located laterally to the median line, is usually a unique congenital anomaly and does not require further evaluation. In sizeable defects, located on the median line, with a membranous appearance that raises the suspicion of a simultaneously damage of the skull and dura mater, cerebral and spinal MRI are recommended. A subjacent neural tube defect

The outcome is usually very good, small defects evolving toward healing within a few weeks through progressive epithelization and atrophic, hairless scarring [8]. In rare cases, hemorrhage and local infections may appear. Large defects of the scalp can be surgically repaired

If aplasia cutis congenita is associated with other anomalies, the outcome depends on their

Deep and small defects of the scalp and skull close spontaneously during the first year of life.

Scalp defects that interest the skull and dura mater can be complicated by sagittal sinus

Micrognathia is a rather frequent clinical craniofacial abnormality, caused by congenital mandibular hypoplasia (**Figure 2**). It is usually associated with a deficient gonial angle, ascending

nant or autosomal recessive. ACC has also been associated with trisomy 13 [11].

must be confirmed or excluded. Treatment for ACC is usually conservative [7].

the lesion and its association with other malformations.

508 Congenital Anomalies - From the Embryo to the Neonate

*4.1.2.1. Management*

*4.1.2.2. Prognosis*

severity.

*4.1.3. Mild micrognathia*

ramus, and mandibular corpus.

using autologous or biological grafts.

Larger-sized defects require surgical correction.

thrombosis and are associated with a mortality rate greater than 50%.

It can appear as a minor and isolated abnormality, or may be severe, as part of a genetic syndrome, frequently causing postnatal complications.

Congenital mandibular hypoplasia occurs either through intrauterine deformation or malformative mechanisms, as a result of a primary intrinsic growth disorder [12, 13].

The mandible is formed from the neural crest, beginning with the onset of the 4th week of gestation, the cells migrating to the upcoming region of the head and neck and with the initiation of the formation of the gill arches. From the first branching arch, two prominences develop, the mandibular and the maxillary one. The mandibular protrusion will form the mandible, and the jaw will form the jaw bone, the zygomatic bone and the squamous part of the temporal bone.

It is likely that congenital mandibular hypoplasia results from poor or insufficient development of the neural crest, or by means of altered migration process to the first branch of the gill, during the 4th week of gestation.

The diagnosis of micrognathia in neonates requires a careful clinical evaluation, to identify other associated craniofacial abnormalities, such as cleft palate or the coexistence of other congenital anomalies. The maxillary, the zygomatic bone, the temporal bone, the cranial vault and the cervical spine represent the other anatomical regions that can be affected.

In the clear majority of cases that include, among the first clinical signs – micrognathia, the diagnosis of genetic syndromes can be suspected on clinical examination. Subsequently, the case requires confirmation by genetic testing, as in deletion syndrome 22q11 cases.

Approximately 60 syndromes associated with micrognathia have been described, such as [12]:

#### **Aneuploidic syndromic**

