Teaching Case

17-year-old female patient who underwent a chest radiograph before otorhinolaryngological surgery. On physical exam, she has brachycephaly, prominent forehead, hypertelorism, ogival palate and small teeth. Furthermore, she can bring her shoulders together to almost touch each other.

Previous imaging studies are reviewed.

PA chest radiograph (Fig. 1) shows absent clavicles (white circle), dysplastic scapulae (white arrow), and multiple arch fusion defects on the posterior aspect of the lower cervical vertebrae (yellow arrows).

Multiple nonenhanced head CT images show the principal bone (Fig. 2) and otorhinolaryngological (Fig. 3) abnormalities such as persistent metopic suture, multiple Wormian bones through both lambdoid sutures, anterior and posterior arch fusion defects, leftward septal deviation and absence of nasal bones, hypoplasia of both maxillary sinuses and the choanae, ogival palate and absence of mastoid pneumatization with partial occupation of both middle ears due to chronic otitis media.

Orthopantomography (Fig. 4) demonstrates crowded and supernumerary teeth.

Cleidocranial dysplasia [CCD; OMIM 119600] is a rare hereditary skeletal disorder characterized by abnormalities involving membranous and endochondral bone formation [1]. It is caused by RUNX2 [CBFA-1] gene mutations [6p21] [2], a family of genes that are required for the differentiation of osteoblasts and skeletal development.

The prevalence of CCD is approximately one per million and does not differ by race or gender [1]. In most cases, the inheritance is autosomal dominant [1], but the disorder may occur sporadically.

Some clinical features may be recognized at birth or early childhood and include delayed closure of the cranial sutures, a prominent forehead, short stature, and dental abnormalities [3]. Hypoplastic or absent clavicles are characteristic, leading to a wide range of movements of the shoulders, being able to approximate them in front of the chest [4]. Intelligence is usually normal [3].

Conventional radiography is the most important modality of imaging for evaluating CCD. In this case, we have reviewed some of the most characteristic radiological features: hypoplastic or absent clavicles [Fig. 1], scapulae deformities [Fig. 1], delayed bone ossification with wide-open fontanelles [Fig. 2a], or fusion defects of the vertebral arches [Fig. 2C-E], Wormian bones [Fig. 2b,2d-e], crowded and supernumerary teeth [Fig. 4], otorhinolaryngological abnormalities like absent nasal bones [1] [Fig. 3a], hypoplastic maxillary sinuses [Fig. 3B] and abnormal pneumatization of the mastoid sinus [Fig. 3c]. Pelvic anomalies are common, produced by delayed ossification of the pelvic bones, and include wide pubic symphysis and widened sacroiliac joints, among others [2]. Many other radiographic abnormalities may be present but exceed the goal of this case [3].

The diagnosis of CCD is established when typical clinical and radiographic findings are present and/or by the identification of a heterozygous pathogenic variant in RUNX2 [CBFA1] by gene testing [2].

Life expectancy and psychomotor development are usually normal [3].

Treatment is focused to prevent complications and treating them once they have appeared [2]. Some of the most frequent issues are scoliosis and dental abnormalities, which may require surgery or orthodontic treatments [3].