Sarcoidosis mimicking metastases in an echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase positive non-small-lung cancer patient: A case report

BACKGROUND: Rearrangements of the anaplastic lymphoma kinase (ALK) gene (ALK-positive) represent an oncogenic driver in approximately 3%-5% of non-small-lung cancer (NSCLC) patients. Sarcoidosis is a multisystem disease, and its reported incidence in Asia is 1 or less per 100000 people per year. The co-occurrence of sarcoidosis and ALK-positive NSCLC is rare, and ALK-positive lung cancer is likely to spread quickly. Therefore, the co-occurrence of sarcoidosis is more easily misdiagnosed as metastatic lung cancer by radiological examination. CASE SUMMARY: A 50-year-old man had a nodule in the left superior lobe, many small nodules in left superior and right lungs, and enlarged bilateral hilar, mediastinal, and right supraclavicular lymph nodes. Computed tomography-guided pulmonary biopsy of the nodule in the left superior lobe revealed echinoderm microtubule-associated protein-like 4 gene-ALK positive NSCLC with concomitant noncaseating granuloma. This patient was treated with crizotinib. Thirty days later, a chest computed tomography scan revealed a dramatic decrease in the size of the left superior lobe nodule; however, the lesions in the right lung progressed. The right supraclavicular lymph nodes showed granulomas, and no tumor cells were identified in the specimens. The angiotensin-converting enzyme level was high. After 1 wk of methylprednisolone treatment, a significant response of all lesions was revealed. Following radical resection of the lung cancer, noncaseating granulomas were observed in both lung tissues and lymph nodes, which resulted in a diagnosis of echinoderm microtubule-associated protein-like 4-ALK positive NSCLC accompanied with sarcoidosis. CONCLUSION: Our experience illustrates that pathological evidence is needed to confirm metastatic disease, especially when some suspected metastatic lesions are negative for malignancy.