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.

Psoriasis is a chronic, immune-mediated dermatosis that affects approximately 125 million people worldwide. Traditionally considered a dermatologic condition, it is now perceived as a systemic disease with numerous comorbidities. While its associations with psoriatic arthritis, metabolic syndrome, and psychiatric disorders are well established, less attention has been given to its coexistence with other dermatoses. This narrative review aims to explore and summarize the existing evidence on the relationships between psoriasis and other skin diseases, highlighting potential overlaps in clinical presentation, pathogenesis, and treatment challenges. Psoriasis may coexist with several inflammatory and autoimmune skin disorders, including atopic dermatitis, lichen simplex chronicus, anti-p200 pemphigoid, pityriasis rubra pilaris, seborrheic dermatitis, inflammatory linear verrucous nevus (ILVEN), Sneddon-Wilkinson disease, and vitiligo. The review highlights the shared genetic pathways (e.g., the Th1/Th17 axis and IL-17 pathway), diagnostic challenges (e.g., sebopsoriasis and psoriasis-eczema overlap), and therapeutic considerations (e.g., paradoxical reactions to biologics and effectiveness of JAK inhibitors in both psoriasis and vitiligo). The coexistence of psoriasis with other dermatoses is more common and clinically significant than previously appreciated. Recognizing these associations is crucial for an accurate diagnosis, avoiding mismanagement, and optimizing individualized treatment strategies. Further research is needed to elucidate the underlying mechanisms and improve the multidisciplinary care for patients with complex dermatologic presentations.

Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare type of epidermal nevus characterized by an inflammatory appearance, intense pruritus, and a tendency to be resistant to treatment. We present here, the case of a 7-year-old boy who presented with a widespread inflammatory skin lesion on the right side of his body, with some of the eruption following Blaschko's lines. He also had an associated contracture in the ipsilateral limb and short stature. Initially, we suspected this may be a rare case of CHILD syndrome in a boy. However, after further investigation, we confirmed the diagnosis as a severe form of ILVEN.

Linear nevus sebaceous syndrome (LNSS) is a rare neurocutaneous syndrome part of the epidermal nevus syndromes group, characterized by the presence of sebaceous nevi and other extracutaneous lesions genetically related to RAS family gene mutations. Sialadenoma papilliferum (SP) is a rare benign intraoral neoplasm which is usually BRAF or HRAS mutated. We report a case of a young female girl diagnosed with a LNSS who developed a SP which had a KRAS mutation. This is the first case of SP with a KRAS mutation in the context of a LNSS.

Linear nevus sebaceous syndrome (LNSS) is a neurocutaneous syndrome associated with systemic complications that involve multiple organs, including the skin, central nervous system, eyes, and skeleton. LNSS is considered to be caused by mosaic RAS gene mutation. In this report, we present an autopsy case of LNSS in a Japanese boy. The affected neonate had hydrops fetalis and was born at 28 weeks and 4 days of gestation, weighing 2104 g. He had bilateral inverted eyelids, verrucous linear nevus separated along Blaschko's line, myocardial hypertrophy, and pharyngeal constriction, and underwent intensive treatment in NICU for arrhythmia, hydrocephalus, and respiratory distress. The hydrocephalus progressed gradually and he died at the age of 181 days, 12 days after a sudden cardiac arrest and recovery. KRAS G12D mutation was found in a skin biopsy specimen but not in blood cells, suggesting a postzygotic mosaicism. Autopsy revealed novel pathological findings related to LNSS, including intracranial lipomatous hamartoma and mesenteric lymphangioma, in addition to previously reported findings such as multicystic dysplastic kidney. There was the limited expression of mutated KRAS protein in kidneys.