Rare Adenosquamous Lung Cancer Inducing Large Hemorrhagic Pericardial Effusion in An Undiagnosed Patient

While lung cancer is the leading cause of cancer mortality, only 2% of non-small cell lung cancer (NSCLC) cases are classified as the adenosquamous subtype. Here we present a case of a middle-aged man who presented with atypical symptoms of massive malignant hemorrhagic pericardial effusion without cardiac tamponade, induced by adenosquamous non-small cell lung carcinoma. Malignant hemorrhagic pericardial effusions are rare, and large volume ones are even rarer. The patient’s advanced malignancy was undiagnosed at presentation and was only discovered through investigations carried out for his pericardial disease. Malignant pericardial effusion may be the initial symptom of malignancy in some patients. Furthermore, adenosquamous carcinoma is a rare type of NSCLC whose response to chemotherapy is limited. Further studies of this rare subtype are warranted to improve patient prognosis.