Alles wat je moet weten over Aplasia Cutis - Een diepgaand overzicht van deze huidaandoening

Histologie

Konvolute fehlgebildeter Haarfollikel mit meist zahlreichen, reifen Talgdrüsenläppchen, die sich traubenartig um den meist erweitereten Ausführungsgang gruppieren. Vermehrung abortiver, apokrin oder auch ekkrin differenzierter Drüsen.

• Präpubertär: Das Oberflächenepithel ist leicht akanthotisch, in der oberen Dermis zeigen sich unreife Talgdrüsenkomplexe und Infundibulumstrukturen. Haarwurzeln und Terminalhaare fehlen vollständig.
• Postpubertär: Es zeigen sich verruköse Epidermishyperplasie sowie mächtige Talgdrüsenkomplexe mit unterschiedlich entwickelten apokrinen Drüsen.

In einer größeren Studie an 168 Fällen wurde folgendes Strukturen mit folgender Häufigkeit nachgewiesen (Kamyab-Hesari K et al. 2016)

• Talgdrüsenhyperplasie (93.5%)
• Primitive Haarfollikel (76.8%)
• Ektopische apokrine Drüsen (55.4%)
• Abnorme duktale Strukturen (24,8%)
• Neoplastische Formationen (5,4%: Trichoblastome, Trichilemmome, Syringocystadenoma papilliferum).

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Consent obtained from parent(s)/guardian(s).

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Lokalisation

90% der Fehlbildungen betreffen das Capillitium (etwa 45% den Bereich der Parietalregion), seltener in absteigender Häufigkeit sind Gesicht, Retroaurikulärregion, Nacken, Rumpf oder Genitalien betroffen. Eine absolute (zu vernachlässigende) Rarität ist das Auftreten im Schleimhautbereich.

Altersabhängiges klinisches Bild:

• Zu diesem Zeitpunkt zeigt sich je nach Lokalisation ein solitärer, vollständig symptomloser, ovaler bis bizarr konfigurierter (länglich mit zipfeligen Ausläufern), weißlich-gelblicher oder hautfarbener, wachsartiger, stets haarloser Fleck bzw. eine entsprechende, leicht erhabene, oberflächenglatte Plaque. Da der Naevus sebaceus am häufigsten am Capillitium auftritt, ist das hervortretende klinische Leitsymptom die umschriebene Haarlosigkeit (Alopezie). Wichtig hierbei ist der klinische Befund des "Fehlens der Follikel" (Bemerkung: die Follikelorgane sind im Bereich der Läsion fehlentwickelt, keine Ausbildung eines Haarfollikels!)

• Im Laufe der Kindheit kein aktives Flächenwachstum. Größenwachstum analog zum Körperwachstum.

• In der Pubertätphase und später bei jüngeren Erwachsenen erfolgt ein Dickenwachstum der meist völlig symptomlosen Hautveränderung. Entwicklung einer weiterhin unbehaarten, beetartigen, warzigen Plaque von nun gelb-roter oder gelb-brauner (Talgdrüsenenwachstum während der Pubertät) Farbe und schwammig-fester Konsistenz.

4. Spätes Erwachsenenalter:

• Zunehmend verruköse Oberflächgestaltung der Läsion, vereinzelt auch hautfarbene oder blau-schwarz gefärbte Knoten (s.u. Komplikationen)
• Anordnung: Meist bizarr konfigurierter, auch lineare Anordnung.

Case Report

Anamnesis and Status before Treatment

A boy was born at 38 gestational weeks to healthy parents with a healthy 3-year-old son. At delivery, the midwife noticed a skull defect, and the child was moved directly to the neonatal department. There he was examined by a dermatologist and diagnosed with ACC ( Fig. 1 ). Magnetic resonance imaging 4 days after birth revealed a complete lack of skull bone down to the dura mater and a small area of cerebral ischemic changes. The ischemic area was also seen with computed tomography at 19 days.

Six-day-old boy before revision.

The boy's grandfather on the mother's side was born with an alopecic scar on the vertex of his head. Physiologic status in general—such as circulation, neurology, natural functions, and birthweight (3,910 g)—was normal. His Apgar scores were 9/9/9. Eye examinations revealed moderate bleeding on both retinas, probably from the time of birth. In addition, cutis marmorata (which his brother had at the same age and has been associated with ACC 7 14 ) prompted examination by a cardiologist who did not find any heart or circulatory abnormalities.

Conservative Treatment Strategy

The boy underwent surgical revision of the defect site under general anesthesia on day 7 and also at the age of 21 days. Initially, the anterior part of the defect showed a clean nonirritated wound with signs of healing. The posterior part of the defect contained a superficial hematoma covered by a thin membrane. After incision, an old hematoma was revealed and removed, together with thrombotized veins that were cut and coagulated to prevent further hemorrhage and infection. Large areas showed signs of initial bone formation, and there were no signs of infection at either time.

Introduction

How best to treat rare congenital diseases such as aplasia cutis congenita (ACC) is still being debated. The best source would certainly be prospective randomized studies, but these cannot be performed due to the limited number of cases. The number of newborns affected with ACC is estimated to be 1 to 3 in 10,000, and the within-group variation is large. Exposure to teratogens during the fetal period 1 or genetic predisposal (with mainly autosomal dominant inheritance) may play a role in the development of ACC. In Adams-Oliver syndrome, scalp ACC is most often found together with terminal transverse limb defects. 2 3 However, the pathogenesis is often unknown, and the condition could possibly be caused by early fetal vascular disruptions or incomplete closure of the ectodermal surface of the neural tube.

Different etiologies have been linked to specific subgroups of ACC that were classified by Frieden 4 and by Sybert. 5 The subgroups reflect the ability of ACC to affect the vertex, the body, or the limbs, and its possible association with cerebral disorders and malformation syndromes. A review by Demmel (1975) 6 included 474 patients and showed that 85.8% of single defects affected only the scalp, which would be classified as group 1 by both Frieden 4 and Sybert. 5 In group 1 ACC, the skull bone and the dura are affected in ∼ 20 to 38% of larger defects. 6 Thus the inner meninges and the sagittal sinus may be exposed. Fatal complications may be due to exposure of vital structures, large wound area, and possibly vascular hemorrhage and infections. The mortality rate for ACC has been reported to be ∼ 20%, with a higher risk when the condition is associated with multiple congenital anomalities. 6

Because of the severe complications mentioned and also the fragile state of newborns, optimal treatment strategies would be of great value. The treatment strategies that are currently possible are conservative treatment, surgical treatment, or the two combined. In addition, initial treatment can be separated from late reconstructive treatments. Conservative treatment is a current trend for management in the neonatal period. 7 This strategy includes various dressings—adhering or nonadhering—and with or without antibacterial properties such as silver coating, 8 9 10 and allografts. 11 If the dura is exposed, the wound should be kept moist and covered at all times to avoid risk of eschar formation and drying, which may lead to rupture of the dura. 12 Local or pedicled scalp flaps (with or without primary closure) or skin grafts for soft tissue coverage are the most commonly reported surgical techniques. 13 Skin expansion, free flaps, and bone grafts may also be performed initially or as delayed cranioplastic treatments. Due to the variation in size, the tissue layers involved, position of the defect, and concurrent medical conditions, considerations must be made on an individual basis for all patients.