# Utilizing a Confronting Upside-Down Approach for IgG4-Related Posterior Mediastinal Fibrosis: A Report of a Rare Case

## TL;DR

A rare case of IgG4-related posterior mediastinal fibrosis was diagnosed and treated using a specialized surgical technique.

## Contribution

The study presents a novel surgical approach for biopsy in challenging thoracic areas.

## Key findings

- The confronting upside-down VATS technique enabled safe and effective tissue sampling.
- IgG4-related posterior mediastinal fibrosis was confirmed through histopathological analysis.
- Treatment with prednisolone improved visual acuity and symptoms over time.

## Abstract

IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory condition mostly characterized by elevated serum IgG4 levels, organ involvement, and tissue fibrosis. Mediastinal fibrosis is a rare manifestation and is infrequently reported in clinical practice.

A 59-year-old man with progressive visual impairment underwent an evaluation, revealing an elevated serum IgG4 concentration of 1470 mg/dL. Orbital magnetic resonance imaging (MRI) showed an enlargement of multiple nerves, including the supraorbital and oculomotor nerves, and computed tomography (CT) identified a posterior mediastinal mass adjacent to the 6th-11th thoracic vertebral bodies without hilar or mediastinal lymphadenopathy. To obtain a definitive diagnosis, a biopsy was performed using the confronting upside-down video-assisted thoracoscopic surgery (VATS) approach. This technique, utilizing ports placed in higher intercostal spaces (ICS), provided optimal visualization and allowed safe and sufficient tissue sampling. Histopathological examination confirmed IgG4-positive plasma cell infiltration and fibrosis, meeting the diagnostic criteria for IgG4-related posterior mediastinal fibrosis. Five days post-surgery, oral prednisolone (PSL) therapy was initiated at 50 mg/day. This resulted in a significant improvement in visual acuity, with further recovery observed over three months as the PSL dose was tapered.

IgG4-related posterior mediastinal fibrosis is an uncommon condition, requiring biopsy for an accurate diagnosis. The confronting upside-down VATS technique ensures safe, precise tissue sampling with minimal complications, offering better visualization and access to challenging thoracic areas, making it a valuable approach for both biopsy and broader thoracic surgeries.