Encephalocraniocutaneous Lipomatosis
A number sign (#) is used with this entry because of evidence that encephalocraniocutaneous lipomatosis (ECCL) is caused by postzygotic somatic activating mutation in the FGFR1 gene (136350) on chromosome 8p11.
DescriptionEncephalocraniocutaneous lipomatosis (ECCL) is a neurocutaneous disorder characterized by ocular anomalies, skin lesions, and central nervous system (CNS) anomalies (Moog et al., 2007).
The malformations in ECCL are patchy and asymmetric. The most characteristic skin anomaly is nevus psiloliparus, a well-demarcated, alopecic fatty tissue nevus on the scalp, seen in 80% of affected individuals. Other dermatologic features include frontotemporal or zygomatic subcutaneous fatty lipomas, nonscarring alopecia, focal dermal hypoplasia or aplasia of the scalp, periocular skin tags, and pigmentary abnormalities following the lines of Blaschko. Choristomas of the eye (epibulbar dermoids or lipodermoids) are also present in 80% of patients, and can be unilateral or bilateral. Characteristic CNS features in ECCL include intracranial and intraspinal lipomas, seen in 61% of patients, and less often cerebral asymmetry, arachnoid cysts, enlarged ventricles, and leptomeningeal angiomatosis. A predisposition to low-grade gliomas has also been observed. Seizures and intellectual disability are common, but one-third of affected individuals have normal intellect. Skeletal manifestations include bone cysts and jaw tumors, such as odontomas, osteomas, and ossifying fibromas (summary by Bennett et al., 2016).
Clinical FeaturesEncephalocraniocutaneous lipomatosis was first described by Haberland and Perou (1970) as a new example of ectomesodermal dysgenesis characterized by profound mental retardation, early onset of seizures, unilateral temporofrontal lipomatosis, ipsilateral cerebral and leptomeningeal lipomatosis, cerebral malformation and calcification, and lipomas of the skull, eye, and heart.
Nowaczyk et al. (2000) reported a male infant with ECCL, in whom prenatal sonogram showed normal intracranial structures at 28 weeks of gestation, but at 38 weeks showed asymmetry of the cerebral hemispheres and ventriculomegaly. At birth he had asymmetry of the cranial contour attributed to the presence of fleshy plaques, 1 over the left temple and another extending in a semicircular manner almost to the vertex. He also had a notch in the left upper eyelid, 2 hard excrescences lateral to the notch, and a lipodermoid plaque over the lateral aspect of the sclera of the left eye. In addition, there was a small area of cutaneous focal hypoplasia near the left temple, and a capillary hemangioma over the right antecubital fossa extending onto the upper arm. MRI at age 6 weeks demonstrated a porencephalic cyst on the left, hemiatrophy of the left cerebrum with cortical dystrophy, and a lipoma in the middle cranial fossa. istologic examination of the resected scalp lesion confirmed the presence of a fibrolipoma hamartoma. Nowaczyk et al. (2000) stated that the characteristic lesions of ECCL are typically nonprogressive after birth, but noted that the sonographic evaluation in this patient suggested that there is antenatal progression of intracranial abnormalities. However, calcification of the affected cortex develops postnatally, and this patient showed the characteristic double-contour 'gyriform' calcifications of the affected region of the CNS at 11 months of age.
Moog (2009) reviewed the clinical features of 54 patients with ECCL. Eye anomalies (mainly choristoma) and skin lesions (nonscarring alopecia, nevus psiloliparus, subcutaneous fatty masses, nodular skin tags, and aplastic scalp defects) may be unilateral or bilateral and occur in a consistent pattern. Central nervous system anomalies consist of intracranial and intraspinal lipomas, congenital abnormalities of the meninges, and putative focal vascular defects resulting in highly asymmetric changes. About two-thirds of the patients have normal development or mild retardation only, and half of them have seizures. Aortic coarctation, progressive bone cysts, and jaw tumors may be associated.
Prontera et al. (2009) described a 5-year-old girl with ECCL and a family history of multiple lipomatosis (FML; 151900). The patient had lipomas on the face, alopecia areata, coloboma of iris, chorioretinitis, bilateral epibulbar dermoid, complex partial crises, moderate tricuspid valve insufficiency, increased pulmonary pressure, intracranial lipomas, leptomeningeal angiomatosis, intracranial calcification, hypoplastic corpus callosum, arachnoid cyst of the right temporal lobe, enlargement of the right ventricle, microgyria of the temporal and occipital right lobes, osteolytic lesion in the right jaw, including irregular zones of calcification, ossification and dental elements (odontogenic jaw tumor), moderate speech delay, and macrocephaly. Her father and her paternal grandmother had multiple benign lipomas affecting limbs and trunk that appeared during the second and third decade of life.
Delfino et al. (2011) described 3 unrelated boys with ECCL with typical dermal, ocular, and central nervous system anomalies. One patient also had a sphenoethmoidal lesion that slowly regrew 2 times after surgical resection. Histologic evaluation confirmed the benign nature of the lesion, which was diagnosed as fibrous dysplasia. Delfino et al. (2011) suggested that benign bone tumors may be a component of ECCL.
Kupsik and Brandling-Bennett (2013) reported an infant girl with ECCL who presented at birth with an alopecic plaque on the scalp and corneal lesions. Examination at 3 weeks revealed a soft smooth alopecic plaque on the right scalp near the vertex, extending onto her forehead to the right eyebrow. In addition, she had circular plaques, similar in appearance and texture to the scalp lesion, arranged in a linear configuration on the right temporal region, as well as several yellow to pink papules located on her right upper eyelid, right lateral canthus, and right cheek. In each eye, there was a pink telangiectatic plaque in a limbal distribution extending from the sclera to the cornea; these were diagnosed as limbal dermoids, a form of ocular choristoma. MRI at 2 months showed extraaxial fluid in the anterior portion of the temporal region, with fatty dural thickening along the base of the middle cranial fossa. Neurologic examination was normal.
Bieser et al. (2015) reported a male infant who was noted at birth to have multiple skin tags on his right eyelid and anterior to the right ear, in addition to a region of right parietal alopecia with a pink fluctuant plaque and thin, light hair covering. He had 4 small areas of cutis aplasia on the right side of his head, and a shallow sacral dimple. Echocardiogram revealed ventricular septal defect, and initial brain MRI was normal except for possible parietal lipoma. Repeat MRI at 3 months of age due to failure to thrive showed a homogeneous enhancing mass in the hypothalamic region with extension into the suprasellar cistern and the posterior aspect of the optic chiasm, consistent with low-grade glioma. The patient underwent partial debulking of the tumor; pathology revealed a grade II pilocytic astrocytoma with pilomyxoid features. Bieser et al. (2015) stated that this was the fourth case of low-grade glioma in a patient with ECCL.
DiagnosisDifferential Diagnosis
Wiedemann and Burgio (1986) reviewed cases of ECCL and concluded that the disorder is a variant of Proteus syndrome (176920). Dean and Cole (1988) also raised this possibility. On the other hand, McCall et al. (1992) studied 3 patients with an array of defects associated with the Proteus syndrome and related hamartoneoplastic conditions. They compared the findings in these 3 patients with those of 50 others with Proteus syndrome and 9 with ECCL reported in the literature. They concluded that Proteus syndrome and ECCL are distinct entities even though some clinical manifestations are shared and a few patients have manifestations of both disorders.
Rizzo et al. (1993) reported a patient with manifestations of ECCL and Proteus syndrome: multiple lipomas of the head, neck, paravertebral region, and heart; hyperostosis of the skull; rugose, yellow-brown skin pigmentation; vertebral anomalies; and alopecia. From a comparison with other cases, they concluded that these disorders represent a continuum rather than distinct entities, supporting the concept of somatic mosaicism, lethal in the nonmosaic state.
McMullin et al. (1993) described 2 unrelated children with diffuse swelling of one cheek and hypertrophy of the underlying maxilla and mandible. Both developed verrucous pigmented streaks over the area of swelling and had epilepsy and severe mental subnormality. One of the children had a contralateral hemiplegia, and his condition was progressive. The other child had no focal neurologic signs, and his disease seemed to be nonprogressive. Although the facial appearance suggested ECCL syndrome, no lipomata could be demonstrated. McMullin et al. (1993) suggested that the 2 cases may represent part of a spectrum of conditions, including the ECCL syndrome and Proteus syndrome.
Haramoto et al. (1995) described a sporadic case of hemifacial hamartomatous hyperplasia consisting of sebaceous nevus-like skin changes, subcutaneous lipomatous mass, cranial bone hyperplasia, and bony change of the meninges. The lesion involved the anterior half of the face and cranial base and was delimited immediately by the midline. This was thought to represent somatic mosaicism for a dominant mutation, lethal in its nonmosaic state, and to be a variant of Proteus syndrome.
Moog et al. (2007) concluded that although ECCL and Proteus syndrome share several features in common, including lipomas, hyperostosis of the skull, mental retardation, and seizures, they are distinct entities. Moog et al. (2007) stated that lipomas and fatty tissue nevi are nonprogressive and present at birth together with ocular and cerebral anomalies in ECCL. In addition, a cerebriform connective tissue nevus, one of the characteristics of Proteus syndrome, and progressive asymmetric, distorting limb overgrowth are not seen in ECCL.
Ardinger et al. (2007) presented evidence that the oculoectodermal syndrome (OES; 600268) is a mild variant of ECCL, differing primarily by lack of intracranial anomalies on brain imaging.
InheritanceMoog (2009) suggested that ECCL is caused by mosaicism for a mutated autosomal gene involved in multiple mesenchymal tumors and vasculogenesis, with or without a second hit event.
PathogenesisMoog et al. (2007) reported 4 new patients with ECCL and reviewed the brain imaging studies and clinical data of these cases and of 6 previously published ECCL patients. They also reviewed the literature on 42 other patients who had undergone some form of neuroimaging, including 3 cases with probable or uncertain ECCL diagnosis. Thirty-three of the 52 patients showed intracranial lipomas, frequently of cerebellopontine location, and/or spinal lipomatosis. The latter was found in 12 of 13 patients who had imaging studies of the spine. Other frequent findings included congenital anomalies of the meninges, in particular arachnoid cysts, and remarkably asymmetric anomalies caused by putative focal vascular defects, such as partial atrophy of one hemisphere or thin cerebral mantle, porencephalic cysts, and calcifications. Vessel anomalies were found in 9 patients. No correlations between the brain anomalies and the degree of retardation or epilepsy could be established. Moog et al. (2007) stated that these data provide evidence that the brain anomalies in ECCL are not primary brain malformations but arise secondary to a mesenchymal defect affecting mostly neural crest derivatives.
Moog et al. (2007) described 3 boys with characteristic skin, eye, and brain anomalies of ECCL who also had coarctation of the aorta and other congenital heart defects; 2 of them also had recurrent chylothoraces, and 1 also had hyperpigmentation following the lines of Blaschko and leg asymmetry. (All 3 were included in the report of Moog et al. (2007) and 1 had previously been described as having oculocerebrocutaneous syndrome (OCCS; 164180) (patient 2 in Narbay et al. (1996)).) All 3 children developed multiple cystic bone lesions, which progressively spread throughout the skeleton in 1 patient and was shown histologically to be nonossifying fibromas in another. Moog et al. (2007) hypothesized that ECCL may be caused by mosaicism for a mutation in an autosomal gene encoding a factor involved in vasculogenesis and in the development of mesenchymal tumors. They suggested the possible involvement of the HMGA2 gene (600698), which frequently shows cytogenetic alterations in a variety of human mesenchymal tumors and was disrupted by a constitutional rearrangement of 12q in a boy with overgrowth, advanced bone age, cerebellar tumor, and multiple lipomas (Ligon et al., 2005); see familial multiple lipomatosis (FML; 151900).
Prontera et al. (2009) described a child with ECCL and a family history of multiple lipomatosis. They suggested that HMGA2 may be a good candidate for FML and ECCL. They proposed that a germline mutation in a gene like HMGA2 may not only be responsible for dominant FML but also represent a predisposition factor for ECCL.
Molecular GeneticsBennett et al. (2016) performed exome sequencing on DNA samples from multiple affected tissues of 5 unrelated patients with ECCL, and identified 2 mosaic missense variants in the FGFR1 gene (N546K, 136350.0033; K656E, 136350.0034) in 2 patients each, including a 15-year-old boy previously reported by Nowaczyk et al. (2000) and a 2.75-year-old boy studied by Bieser et al. (2015). Targeted resequencing of FGFR1 in multiple tissues from an independent cohort of 4 ECCL patients revealed the N546K mutation in 1 patient, a 5-year-old girl originally reported by Kupsik and Brandling-Bennett (2013). The alternate allele fraction ranged from 23 to 55% in fibroblasts from affected tissues, but the mutations were not detected in saliva or blood samples. Neither variant was found in the Exome Variant Server, ExAC, or dbSNP databases. Bennett et al. (2016) stated that these 2 residues are the most commonly mutated residues among FGFR1 mutation-containing tumors in the Catalogue of Somatic Mutations in Cancer (COSMIC) database, and noted that most of the tumors associated with substitutions in these 2 residues are central nervous system gliomas, including pilocytic astrocytomas, the same type of tumor seen at increased frequency in patients with ECCL.