Cause Analysis of Misdiagnosis of Primary Lung Cancer with Paraneoplastic Syndrome in Dermatomyositis as the Initial Manifestation

LI Jinyao; SONG Enfeng

doi:10.3969/j.issn.1002-3429.2025.11.002

Abstract：Objective To analyze the causes and clinical characteristics of primary lung cancer patients with paraneoplastic syndrome in dermatomyositis as the initial manifestation,and to summarize the causes of misdiagnosis and preventive measures through case analysis of primary lung cancer patients with paraneoplastic syndrome in dermatomyositis.Methods From May 2022 to October 2023,4 cases of misdiagnosed primary lung cancer with paraneoplastic syndrome in dermatomyositis as the initial manifestation were retrospectively analyzed.Results Four patients were misdiagnosed as allergic dermatitis(n=2),seborrheic dermatitis(n=1)and eczema(n=1)due to proximal limb muscle weakness and characteristic rash.The condition of 4 patients was not improved after corresponding treatment,and chest CT examination showed lung space occupying lesions,and further lung tissue puncture and pathological examination was performed to confirm dermatomyositis complicated with primary lung cancer.The misdiagnosis lasted 1-2 months.After the diagnosis,all the 4 patients received chemotherapy,and their conditions were improved and discharged.After 1 year of follow-up,3 patients died and 1 patient was still in stable condition.Conclusion Paraneoplastic syndrome in dermatomyositis should be considered by clinicians,and the clinical characteristics of patients should be comprehensively analyzed during diagnosis and treatment.When there is proximal muscle weakness,dermatomyositis typical rash,dysphagia,chest CT scan showing lung space occupying lesions and elevated tumor markers,the possibility of dermatomyositis combined with primary lung cancer should be considered.Lung biopsy should be performed as early as possible for early diagnosis.