# Pulmonary Enteric Adenocarcinoma in a Super‐Elderly Patient: A Case Report and Literature Review

## TL;DR

This paper reports a rare case of lung cancer in an 85-year-old man, showing successful diagnosis and surgery despite his age.

## Contribution

The case highlights the use of immunohistochemistry for diagnosing PEAC and successful surgery in a super-elderly patient.

## Key findings

- The patient had a 9-year history of a growing pulmonary nodule before diagnosis.
- Immunohistochemistry confirmed PEAC with CK7, CK20, and CDX2 positivity.
- The patient remained disease-free one year after surgery without adjuvant therapy.

## Abstract

Pulmonary enteric adenocarcinoma (PEAC) is an extremely rare subtype of non‐small cell lung cancer, characterised by histopathological features that resemble colorectal adenocarcinoma. Here, we report a case of PEAC in an 85‐year‐old male who presented with a pulmonary nodule initially identified at the age of 76. Initial PET‐CT (maximum standardised uptake value [SUVmax] = 2.8) was inconclusive, leading to strict follow‐up. Over 9 years, the nodule enlarged significantly (3.2 cm, SUVmax = 8.4). A transbronchial biopsy confirmed adenocarcinoma, and the patient underwent successfully video‐assisted thoracoscopic surgery with lymph node dissection. The histopathological analysis revealed CK7 and CK20 positivity, focal CDX2 positivity, and TTF‐1 negativity, confirming PEAC. Despite advanced age, the patient tolerated surgery well without adjuvant therapy. At the one‐year postoperative follow‐up, he remained disease‐free. This case emphasises the diagnostic utility of immunohistochemistry and the feasibility of surgical management, even in super‐elderly patients with PEAC.

Here, we report a rare case of PEAC in an 85‐year‐old male, emphasising the diagnostic approach, surgical treatment, and favourable postoperative outcome. This case underscores the importance of immunohistochemical markers in establishing the diagnosis and highlights the potential for successful surgical management in a super‐elderly patient.