Malignant pleural effusion due to metastatic squamous cell carcinoma exhibiting pseudoglandular and signet ring-like features: a case report

When metastatic squamous cell carcinoma in pleural effusion is poorly differentiated and exhibits atypical changes such as pseudoglandular and signet ring-like features, vigilance is required during serous fluid cytopathological diagnosis. An accurate diagnosis provides the basis for subsequent clinical treatment.