The concurrence of sarcoidosis and primary lung cancer is very rare. We report a very rare case with a delayed diagnosis of primary lung cancer due to its misdiagnosis as worsening of pulmonary sarcoidosis. A 68-year-old man presented to the outpatient department for evaluation of a mass in the right hilar area with lymphadenopathies in subcarinal and both interlobar areas on chest computed tomography (CT). Sufficient core samples were obtained from subcarinal and bilateral interlobar lymph nodes using endobronchial ultrasonography (EBUS) guided transbronchial needle aspiration (TBNA). EBUS could not reach the right hilar lymph node due to its high angle. The pathologic findings were consistent with sarcoidosis. After 5 months, chest CT revealed aggravation of the right upper paratracheal lymphadenopathy. Assuming worsening of sarcoidosis, he was prescribed an oral corticosteroid for 5 months. However, follow-up chest CT showed a newly developed right lower paratracheal lymphadenopathy and worsening right hilar lymphadenopathy. Bronchoscopy and EBUS were performed once again. Transbronchial lung biopsy from the right upper lobe and EBUS-TBNA from the right lower paratracheal lymph node revealed adenocarcinoma from the lung. Although coexistence of sarcoidosis and lung cancer is very rare, the clinician should consider the possibility of accompanying lung cancer in sarcoidosis patients who are not responding to initial corticosteroid therapy.

中文翻译：

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由于误诊为结节病加重而导致的肺癌延迟诊断：一​​例报告

结节病和原发性肺癌的并发非常罕见。我们报告了一个非常罕见的病例，由于其误诊为肺结节病恶化，导致原发性肺癌的诊断延迟。一名68岁的男子出现在门诊，以评估胸部右X肺门区域的肿物，并在胸部X线计算机断层扫描（CT）上评估了在颌下和两个叶间区域的淋巴腺病。使用支气管内超声（EBUS）引导的经支气管穿刺针吸（TBNA）从软骨下和双侧叶间淋巴结中获得足够的核心样本。EBUS由于角度较大，无法到达右肺门淋巴结。病理结果与结节病一致。5个月后，胸部CT检查显示右上气管旁气管淋巴结肿大。假设结节病恶化，他开了5个月的口服糖皮质激素处方。但是，随访胸部CT显示新出现的右下气管旁淋巴结病和右肺门淋巴结病恶化。再次进行支气管镜检查和EBUS。右上叶经支气管肺活检，右下气管旁淋巴结经EBUS-TBNA检出肺部腺癌。尽管结节病和肺癌并存非常罕见，但临床医生应考虑对最初的皮质类固醇疗法无反应的结节病患者伴发肺癌的可能性。右上叶经支气管肺活检，右下气管旁淋巴结经EBUS-TBNA检出肺部腺癌。尽管结节病和肺癌并存非常罕见，但临床医生应考虑对最初的皮质类固醇疗法无反应的结节病患者伴发肺癌的可能性。右上叶经支气管肺活检，右下气管旁淋巴结经EBUS-TBNA检出肺部腺癌。尽管结节病和肺癌并存非常罕见，但临床医生应考虑对最初的皮质类固醇疗法无反应的结节病患者伴发肺癌的可能性。