# Hemothorax as the Initial Manifestation of KRAS G12D Positive Pulmonary Pleomorphic Carcinoma: A Case Report

## TL;DR

This case report describes a rare lung cancer with a KRAS mutation that caused sudden hemothorax, highlighting the importance of early diagnosis and treatment.

## Contribution

The paper presents the first reported case of hemothorax as the initial manifestation of KRAS G12D-positive pulmonary pleomorphic carcinoma.

## Key findings

- KRAS G12D mutation is associated with rapid tumor growth and hemothorax in pulmonary pleomorphic carcinoma.
- Early recognition and complete resection are critical for improving outcomes in this aggressive cancer subtype.

## Abstract

Pulmonary pleomorphic carcinoma (PPC) is a rare subtype of lung cancer that is characterised by rapid progression and poor prognosis. Hemothorax as the initial clinical presentation of PPC is exceptionally rare and, to the best of our knowledge, has not been previously reported. Here, we report a rare case of a KRAS G12D‐mutated PPC penetrating the visceral pleura, leading to rapid tumour growth and uncontrolled hemothorax. In addition to the high proliferative and invasive potential of the tumour, the oncological properties associated with the KRAS G12D mutation likely precipitated both the abrupt onset and recurrence of massive hemothorax. Early recognition, complete macroscopic resection to achieve definitive haemostasis, and prompt initiation of postoperative therapy are essential to improve clinical outcomes.

We report a rare case of KRAS G12D positive pulmonary pleomorphic carcinoma penetrating the visceral pleura, leading to rapid tumour growth and uncontrolled hemothorax. In addition to the high proliferative and invasive potential of the tumour, the oncological properties of the KRAS G12D mutation likely precipitated both the abrupt onset and recurrence of massive hemothorax. Early recognition and complete macroscopic resection to achieve definitive haemostasis are essential to improve clinical outcomes.