# Histopathologic Features and Molecular Markers of Encephalocraniocutaneous Lipomatosis (ECCL)

## TL;DR

This paper reviews the histopathologic features and molecular markers of ECCL, a rare disorder, to improve diagnostic understanding and clinical decision-making.

## Contribution

The paper synthesizes histopathologic findings and highlights molecular markers like FGFR-1 and KRAS mutations in ECCL.

## Key findings

- ECCL is characterized by cutaneous features such as nevus psiloliparus and central nervous system involvement.
- Mosaic activating mutations in FGFR-1 and KRAS are implicated in ECCL pathogenesis.
- Limited histopathologic descriptions in the literature make ECCL diagnosis primarily clinical.

## Abstract

Encephalocraniocutaneous lipomatosis (ECCL) is a rare congenital neurocutaneous disorder characterized by ocular, skin, and central nervous system manifestations. Despite its recognizable clinical features, such as nevus psiloliparus, histopathologic characterization of ECCL remains limited in the dermatopathology literature, and diagnosis is often clinical. This scarcity of published histopathological descriptions makes diagnostic confirmation challenging and underscores the value of synthesizing the available evidence. This comprehensive review synthesizes reported histopathological findings across cutaneous manifestations highlighting key tissue-level features that may aid diagnostic confirmation. Additionally, we review the emerging role of molecular diagnostics, particularly the identification of mosaic activating mutations in FGFR-1 and KRAS, which have been implicated in ECCL pathogenesis. By integrating clinicopathologic correlations with molecular insights, this review aims to enhance our dermatopathological understanding of ECCL, bolstering diagnostic reasoning and clinical decision making for this rare neurocutaneous condition.