CASE REPORT article
Front. Oncol.
Sec. Thoracic Oncology
Sarcoidosis misdiagnosed as pulmonary malignancy: a case report
Provisionally accepted
- 1Shandong Second Medical University, Weifang, China
- 2Central Hospital Affiliated to Shandong First Medical University, Jinan, China
- 3Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- 4Shandong First Medical University, Jinan, China
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Sarcoidosis is an idiopathic multisystem disease characterized by non-caseating granulomas primarily composed of epithelioid macrophages. The lungs and lymph nodes are the most commonly affected organs. Clinical manifestations of sarcoidosis vary widely, and its radiographic features often overlap with those of malignant tumors, especially pulmonary malignancy, increasing the diagnostic challenge. This article presents a case of sarcoidosis misdiagnosed as pulmonary metastatic in a patient with a history of pulmonary malignancy. Nine months after surgery for left lung adenocarcinoma, the patient had a follow-up that revealed elevated CEA levels (14.98 ng/ml). ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) revealed 18F-fluorodeoxyglucose (¹⁸F-FDG) metabolic hot spots in the right upper lung lobe, bilateral pleura, and spleen, as well as metabolically active lymph nodes in several locations, including the mediastinum, hilum, hepatic hilum, omental bursa, and retroperitoneum. The largest lymph node, located in the mediastinum, had a maximum standardized uptake value (SUV max) of 21.5, indicating intense glucose metabolism and suggesting pulmonary malignancy recurrence with metastasis to the pleura and spleen. To clarify the diagnosis, we conducted a lymph node biopsy and histological examination, which ultimately confirmed sarcoidosis. This case highlights that, in patients with pulmonary malignancy, sarcoidosis can coexist with or occur alternately alongside malignancy, and the imaging features of both conditions lack specificity, potentially leading to misdiagnosis. These observations underscore that reliance on imaging alone is insufficient for differential diagnosis, and that other diagnostic methods, particularly histopathological evidence, should be integrated to achieve a comprehensive assessment.
Keywords: Sarcoidosis, intra-pulmonary metastasis, positron emissiontomography/computed tomography, case report, differential diagnosis
Received: 11 Oct 2025; Accepted: 10 Dec 2025.
Copyright: © 2025 Zhu, Sun, 张, Huang, Zhao, Fan and Xing. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
LiangMing Zhu
Xiaoming Sun
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