关节炎是副肿瘤综合征的一种不寻常表现，出现在多种癌症中，包括肺癌和结直肠癌。它通常会给医生带来诊断挑战，因为它可能很难与更常见的风湿性疾病区分开来。此外，在对称性多关节炎患者中，同时发生癌症是罕见且出乎意料的。患有多关节炎和肺肿瘤的患者应考虑肥厚性肺骨关节病。本报告的目的是强调一名患有副肿瘤性多关节炎的患者的病例，该病例导致确定潜在的同步性肺和结直肠恶性肿瘤的存在。进行淋巴结活检，怀疑卡普兰综合征，但肺叶切除术证实为腺癌。风湿病学家应重新熟悉恶性疾病中的风湿表现。© 2023 地中海风湿病杂志 (MJR)。

Arthritis is an unusual manifestation of paraneoplastic syndrome, appearing in a variety of cancers, including pulmonary and colorectal. It can often pose a diagnostic challenge to physicians, since it may be difficult to distinguish from more commonly encountered rheumatic illnesses. Moreover, synchronous cancers are rare and unexpected in patients with symmetrical polyarthritis. Hypertrophic pulmonary osteoarthropathy is to be considered in patients with polyarthritis and lung neoplasia. The aim of this report is to highlight the case of a patient presenting with paraneoplastic polyarthritis, which led to identifying the presence of underlying synchronous lung and colorectal malignancies. Lymph node biopsy was performed raising suspicion of Caplan's syndrome but lung lobectomy confirmed adenocarcinoma. Rheumatologists should be reacquainted with rheumatic manifestations in malignant diseases.© 2023 The Mediterranean Journal of Rheumatology (MJR).