Histological evidence of MAPK pathway activation across subtypes of adult orbital xanthogranulomatous disease irrespective of the detection of oncogenic mutations.

Adult orbital xanthogranulomatous disease (AOXGD) is a spectrum of histiocytoses with four subtypes. Mitogen-activated protein kinase (MAPK) pathway mutations have been detected in various histiocytic neoplasms, little is known about this in AOXGD. Targeted regions of cancer- and histiocytosis-related genes were analyzed and immunohistochemical staining of phosphorylated ERK (pERK), cyclin D1 and PU.1 was performed in 28 AOXGD and 10 control xanthelasma biopsies to assess MAPK pathway activation. Mutations were detected in 7/28 (25%) patients. Positive staining for pERK and/or cyclin D1 was found across all subtypes in 17/27 (63%) patients of whom 12/17 (71%) did not harbour a mutation. Xanthelasma tissue stained negative for pERK and cyclin D1. Relapse occurred in 5/7 (71%) patients with a MAPK pathway mutation compared to 8/21 (38%) patients in whom no mutation could be detected. Molecular analysis and evaluation for systemic disease is warranted to identify patients at risk of recurrent xanthomatous disease.

Schimmelpenning-Feuerstein-Mims syndrome with orbital choristoma and KRAS mutation: a current review and novel case report.

INTRODUCTION: Schimmelpenning-Feurstein-Mims Syndrome (SFMS) is a rare neurocutaneous disorder. Herein, we describe a novel case and review the phenotypic spectrum and molecular findings of SFMS from an ophthalmology perspective. METHODS: Clinical case including presentation, management, pathology, and genetic analysis is described. A literature search on Schimmelpenning-Feuerstein-Mims and its synonyms, Linear nevus sebaceous syndrome, Organoid nevus syndrome, Jadassohn nevus phacomatosis, and Solomon syndrome, was conducted. An updated review and description of published cases with identified genetic mutations are described. RESULTS: A 13-year-old boy with SFMS presented with acute right eye pain and an enlarging orbital mass. Excisional biopsy of the mass revealed an orbital choristoma. Genetic analysis of the orbital tumor confirmed a KRAS c.35 G>A, p.G12D mutation. A literature search revealed 19 cases of SFMS with mutations in the RAS-pathway. KRAS, HRAS, and NRAS mutations were identified in 74%, 21%, and 5% of patients, respectively. Ophthalmic pathology was seen in 83% of patients. Systemic findings varied and involved the skin, central nervous system, and eyes most commonly. DISCUSSION: SFMS, a rare neurocutaneous disorder, results from postzygotic mosaic mutations in the RAS/MAPK pathway. Patients present with various systemic findings and ophthalmic manifestations occur in most cases. This is the first case description of a KRAS mutation identified in an orbital choristoma in SFMS. The disease is described under various names in the literature, and we propose that all syndromic cases with mosaic RAS mutations be reported under the eponym, SFMS.