# Sarcoidosis With Multiple Bone Lesions Mimicking Advanced Lung Cancer With Multiple Bone Metastases

## TL;DR

A patient with sarcoidosis had bone lesions that looked like advanced lung cancer, but the lesions disappeared after steroid treatment, showing the importance of accurate diagnosis.

## Contribution

Demonstrates that bone sarcoidosis can mimic bone metastases from lung cancer and highlights the diagnostic utility of corticosteroid treatment and biopsy.

## Key findings

- Bone sarcoidosis can present as multiple lesions resembling metastatic cancer.
- Corticosteroid treatment can lead to resolution of PET/CT findings in bone sarcoidosis.
- Biopsy of bone lesions is crucial for differentiating sarcoidosis from malignancy.

## Abstract

Bone lesions in sarcoidosis are more common than previously known. A 59-year-old female with a history of sarcoidosis was referred due to suspected lung cancer. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) revealed numerous bone lesions in addition to abnormal uptake by pulmonary nodules and mediastinal lymph nodes, which mimicked metastatic advanced lung cancer. Biopsy of bone lesions detected epithelioid cell granuloma consistent with bone sarcoidosis. Moreover, prednisolone treatment was tried to exclude malignant disease. One month after prednisolone administration, bone lesions and other abnormal uptake disappeared on PET/CT. Bone sarcoidosis is often asymptomatic and is discovered incidentally as multiple lesions that may require differentiation from malignant disease. Biopsy of bone lesions and administration of corticosteroids may be useful for accurate diagnosis.