To describe the clinical features and management of ocular choristomas in mosaic RASopathy patients. We performed a retrospective single-center case review of all mosaic RASopathy patients. We evaluated for the presence of corneal and epibulbar choristomas and conducted a comprehensive analysis of the imaging, including operative microscope images, slitlamp images, and optical coherence tomography images. In doing so, we provide a precise description for these types of choristomas. Nine patients with mosaic RASopathies, 7 men and 2 women (3 with clinical diagnoses of Linear Sebaceous Nevus Syndrome, 5 with Oculoectodermal Syndrome, and 1 with Encephalocraniocutaneous Lipomatosis), were evaluated. Fourteen eyes with ocular choristomas were identified among the 9 patients-bilaterally in 5 and unilaterally in 4. Molecular confirmation was available in 6 cases, and pathogenic variants in the KRAS gene were identified in all 6. None of the choristomas presented as discrete raised lesions at the limbus alone; they were all relatively flat, very vascularized, and in 4 of the 14 eyes, there was involvement of the visual axis, with 6 having extension with vascularization onto the cornea. All of them extended into the conjunctiva and into the sclera posteriorly. Ocular choristomas with conjunctival and scleral extension, often with concomitant corneal vessels, should alert the clinician to the possibility of a mosaic RASopathy. Management can be complicated and includes measures such as optical iridectomy, anti-VEGF injections, and refractive correction with occlusion therapy, and corneal transplantation may also be considered.

Encephalocraniocutaneous lipomatosis (ECCL) is a rare somatic disorder caused by mutations in various genes of the RAS-MAPK pathway. Distinctive features of ECCL include nevus psiloliparus, scalp alopecia, ocular choristomas, and intracranial lipomas. ECCL is most commonly associated with FGFR1 and KRAS mutations. An NRAS variant causing ECCL has only been reported in the literature once. We present the case of a female infant with ECCL, harboring an NRAS somatic mutation, variant c.37G>C (p.Gly13Arg). This is the second reported case of an NRAS variant in ECCL and the first to document an associated intracranial lipoma. The report highlights the genotypic, clinical, and neuroradiological presentation of ECCL, its overlap and distinctions with other mosaic RASopathies, and reviews the recommended diagnostic approach when ECCL is suspected.

We report a patient with clinically confirmed Schimmelpenning-Feuerstein-Mims (SFM) syndrome but many overlapping features with oculoectodermal syndrome (OES) and encephalocraniocutaneous lipomatosis (ECCL). Whole exome sequencing revealed a mosaic KRAS c.436G>A, p.(Ala146Thr) mutation, previously identified in three OES and ECCL patients. These findings corroborate the evidence of SFM syndrome being a mosaic RASopathy, broaden the phenotypic spectrum of oculocutaneous mosaic RASopathies, and indicate SFM syndrome as a continuum of the OES-ECCL disorder spectrum.

Encephalocraniocutaneous lipomatosis (ECCL), also known as Haberland syndrome, is a sporadic tumor predisposition neurocutaneous disorder, included in the oculoectodermal syndrome group of mosaic RASopathies. ECCL primarily affects the skin, central nervous system and eyes. Key diagnostic features include nevus psiloliparus, a hallmark subcutaneous lipomatous hamartoma associated with alopecia, along with subcutaneous lipomas, focal skin aplasia, and patchy alopecia. Neurologically, intracranial lipomas, particularly in the cerebellopontine angle, are prevalent, along with cortical dysplasia, ventriculomegaly, and vascular malformations. Ocular findings commonly involve choristomas, lipodermoids, and dermoids, which may impair vision. Diagnosis can be made clinically, but further confirmatory genetic testing can in some cases identify a pathogenic variant in the FGFR1 or KRAS genes. Molecular testing aids diagnosis but is not always conclusive. Management is multidisciplinary with focus on symptomatic management, typically involving dermatological, neurological, and ophthalmologic evaluations with consideration of brain and spine neuroimaging and surgical management of tumors. The prognosis varies, with most individuals leading generally normal lives, though there is a risk of developmental delay, seizures, and low-grade gliomas. The severity of CNS involvement does not consistently correlate with cutaneous or ocular abnormalities.

Encephalocraniocutaneous lipomatosis (ECCL) is a rare congenital syndrome and subclassification of oculoectodermal syndrome. Encephalocraniocutaneous lipomatosis may be associated with postzygotic mutations. However, absence of an identifiable mutation does not preclude a diagnosis of ECCL. Encephalocraniocutaneous lipomatosis commonly causes skin, eye, and central nervous system anomalies. Diagnosis can be made through genetic sequencing or standardized clinical criteria. One clinically apparent major criterion for the diagnosis of ECCL is nevus psiloliparus (NP), a fatty nevus with overlying nonscarring alopecia. In this case, a 50-day-old female infant with uncomplicated birth history presented to dermatology clinic for evaluation of 2 superficial cranial masses that had been present since birth without regression or evolution. One of the masses was located within the hairline and demonstrated overlying nonscarring alopecia, suspicious of NP. Because of concern for ECCL, brain magnetic resonance imaging was ordered and revealed 2 intracranial lipomas. Genetic testing was inconclusive. Excision of the masses was performed at the request of the parents for cosmetic purposes. Histologic evaluation of the surgical specimens confirmed the diagnosis of NP and ECCL. A suspected NP should raise concern for ECCL and prompt further evaluation for systemic involvement. In particular, patients with suspected ECCL should be screened for ocular and CNS involvement. Early identification and diagnosis are important for prognostication because patients with ECCL are at increased risk of developing neoplasms of the head and neck and may require more frequent screening examinations.