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Metastasis and Carcinoma Case Studies · Journal article
Medicine · August 14, 2026
Early or partial results. Treat as a signal, not a conclusion.
This is a case report of a 67-year-old woman with pulmonary sarcomatoid carcinoma initially misdiagnosed as thymic carcinoma, who underwent diagnostic surgical resection and received sequential chemotherapy and immunotherapy before dying of rapidly progressive metastatic disease. The case highlights diagnostic pitfalls when anterior mediastinal lung tumours mimic thymic lesions, and notes that PD-L1 positivity did not predict benefit from pembrolizumab in this patient.
Single case report. 67-year-old woman presenting to a local hospital in Hangzhou with chest pain, low-grade fever, and hemoptysis; imaging showed a mass abutting the anterior mediastinum. Initial core needle biopsy was misinterpreted as thymic carcinoma. She was transferred to Zhejiang Hospital, where diagnostic uncer…. Intervention: Video-assisted thoracoscopic wedge resection; docetaxel plus cisplatin chemotherapy; subsequently dose-reduced docetaxel plus pembrolizumab. Hangzhou and Zhejiang Hospital, China.
Patient presented with chest pain, low-grade fever, and hemoptysis; initial core needle biopsy misinterpreted as thymic carcinoma Surgical resection and integrated assessment identified pulmonary sarcomatoid carcinoma with pan-cytokeratin and vimentin positivity, TTF-1 negativity, Ki-67 elevation, PD-L1 tumor proportion score approximately 10% and combined positive score approximately 20% KRAS p.A146T and NRAS p.Q61K mutations identified
Patient received docetaxel–cisplatin followed by dose-reduced docetaxel plus pembrolizumab due to toxicity and progression
Clinicians should maintain suspicion for pulmonary sarcomatoid carcinoma when anterior mediastinal lung lesions with spindle cell morphology are encountered, as they may be misdiagnosed as thymic tumours on small biopsies. This case also illustrates that PD-L1 positivity alone does not guarantee response to immunotherapy in sarcomatoid carcinoma.
Single case report with diagnostic and treatment lessons, but no comparative data, controlled intervention, or outcome metrics that permit evidence-grading of efficacy.
As stated by the source record.
Quoted from the source exactly as published.
Clinicians should maintain suspicion for pulmonary sarcomatoid carcinoma when anterior mediastinal lung lesions with spindle cell morphology are encountered, as they may be misdiagnosed as thymic tumours on small biopsies. This case also illustrates that PD-L1 positivity alone does not guarantee response to immunotherapy in sarcomatoid carcinoma.
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
Rationale: Pulmonary sarcomatoid carcinoma (PSC) is a rare and aggressive subtype of non–small-cell lung cancer. Marked histologic heterogeneity, nonspecific imaging findings, and limited representation in small biopsy specimens can cause diagnostic error, particularly when a pulmonary lesion abuts the anterior mediastinum and mimics a thymic tumor. Patient concerns: A 67-year-old woman presented to a local hospital in Hangzhou with chest pain, low-grade fever, and intermittent hemoptysis. Imaging showed a mass abutting the anterior mediastinum and adjacent lung parenchyma. Core needle biopsy showed predominantly spindle cells with few atypical epithelioid cells in a lymphocyte-rich background and was interpreted as thymic carcinoma. She was subsequently transferred to Zhejiang Hospital for further evaluation. Diagnoses: Continued progression during docetaxel–cisplatin chemotherapy and persistent diagnostic uncertainty prompted video-assisted thoracoscopic wedge resection. The resected tumor showed markedly atypical spindle cells, pan-cytokeratin and vimentin positivity, thyroid transcription factor 1 negativity, and an elevated Ki-67 proliferation index. Programmed death-ligand 1 testing showed a tumor proportion score of approximately 10% and a combined positive score of approximately 20%. KRAS p.A146T and NRAS p.Q61K mutations were identified. Integrated histomorphologic, immunohistochemical, and molecular assessment established the diagnosis of PSC. Interventions: The patient initially received docetaxel plus cisplatin. Because of continued disease progression, declining performance status, and myelosuppression and gastrointestinal adverse effects during platinum-based chemotherapy, cisplatin was discontinued. The patient subsequently received dose-reduced docetaxel plus pembrolizumab as an individualized treatment strategy intended to balance continued systemic therapy with tolerability. Outcomes: The disease progressed rapidly with metastases to the lungs, bone, soft tissue, liver, pancreas, and adrenal gland. The patient died of respiratory failure secondary to widespread tumor dissemination. Lessons: PSC should be considered when an apparent anterior mediastinal mass shows spindle cell morphology or discordant clinicoradiologic and pathologic findings. Adequate representative tissue and integrated radiologic, morphologic, immunohistochemical, and molecular assessment are essential. Rapid progression despite docetaxel plus pembrolizumab indicates that programmed death-ligand 1 positivity alone may not reliably predict immunotherapy benefit, while the clinical significance of rare KRAS/NRAS co-mutations remains uncertain.
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