# ROS-1 Positive Pleural Adenocarcinoma Diagnosed by Semirigid Thoracoscope Using Cryo-Probe in a Middle-Aged Lady: A Case Report

## TL;DR

A middle-aged woman with pleural adenocarcinoma was diagnosed using a semirigid thoracoscope and cryo-probe, revealing a rare ROS-1 positive cancer that responded well to targeted therapy.

## Contribution

This case highlights the utility of pleural cryobiopsy via semirigid thoracoscopy in diagnosing rare, targetable lung cancers like ROS-1 positive adenocarcinoma.

## Key findings

- Pleural cryobiopsy using a semirigid thoracoscope provided a larger, better-preserved tissue sample for accurate diagnosis.
- ROS-1 positivity was identified, allowing the patient to benefit from crizotinib with significant tumor regression.
- The case demonstrates the challenges in diagnosing pleural neoplasia and the value of advanced biopsy techniques.

## Abstract

ROS-1 positive non-small cell lung cancer (NSCLC) constitutes a lesser-known yet targetable subcategory of lung malignancies, contributing 1-2% of cases. NSCLC management has been revolutionized by molecular profiling, which employs the identification of driver mutations that permit personalized therapy.

A 40-year-old lady presented with gradual right-sided chest pain, dry cough, breathlessness, weight loss, and loss of appetite. Radiology (CECT) showed a right-sided pleural effusion, and pleural biopsy revealed adenocarcinoma. Pleural cryobiopsy was done by a flexible cryo-probe, passed via the working port of a semirigid thoracoscope till the parietal pleura, followed by its activation to freeze the tissue for 3-5s, to ultimately perform an en-bloc resection. Immunohistochemistry revealed ROS1 positivity, but EGFR and ALK were negative. She was initiated on crizotinib, which led to a remarkable clinical response and tumor regression.

Absolute diagnosis of pleural neoplasia can be daunting because of nonspecific imaging and cytology findings, more so if the pathology is in the fibrotic pleura. Pleural cryobiopsy, which employs a semirigid thoracoscope, makes room for larger and better-preserved tissue samples, enhancing the diagnostic yield in complicated scenarios like ours.