# When Positron Emission Tomography (PET) Is Misleading: Ion™ Robotic Bronchoscopy Identifies Organizing Pneumonia and Unmasks a Rare Pulmonary Granular Cell Tumor

## TL;DR

A case shows how PET scans can be misleading in diagnosing lung nodules, highlighting the importance of accurate tissue diagnosis and awareness of rare tumors.

## Contribution

Highlights diagnostic challenges with PET and emphasizes awareness of rare granular cell tumors in pulmonary nodule evaluation.

## Key findings

- PET scan showed increased metabolic activity, but tissue diagnosis revealed organizing pneumonia.
- The case involved a rare granular cell tumor, which is often unfamiliar to physicians.

## Abstract

Pulmonary nodules with increased metabolic activity on positron emission tomography (PET) are frequently presumed malignant; however, inflammatory and rare benign neoplastic processes may produce false-positive findings. A 61-year-old African American male with a history of calcified and non-calcified pulmonary nodules and severe emphysema was referred to our pulmonary nodule clinic from the emergency department after a newly discovered lung nodule was identified on computed tomography (CT) of the chest. Subsequent evaluation demonstrated metabolic activity on PET, raising concern for malignancy; however, tissue diagnosis revealed organizing pneumonia. This case highlights diagnostic pitfalls associated with commonly used imaging and biomarker modalities in the evaluation of pulmonary nodules and emphasizes the importance of clinical awareness of a rare tumor, granular cell tumor (GCT), among physicians who may be unfamiliar with or have never encountered this condition.