Devil in disguise: a rare presentation of lung sarcomatoid carcinoma masking as empyema

SESSION TITLE: Lung Cancer Case Report Posters 17 SESSION TYPE: Case Report Posters PRESENTED ON: 10/09/2023 02:10 pm - 02:55 pm INTRODUCTION: Pulmonary sarcomatoid carcinoma (PSC) is a rare form of highly invasive, biphasic type of non-small cell lung carcinoma (NSCLC) composed of both epithelial and mesenchymal elements with poor prognosis, accounting for 0.1-0.4% of all malignant tumors of the lung, predominated in male smokers with over 65 years of age. We present a case of a 74-year-old man who initially presented with clinical features identical to lung empyema later diagnosed with advanced PSC. CASE PRESENTATION: A 74-year-old ex-smoker with a history of Crohn's disease and ocular myasthenia gravis on immunosuppression presented with dyspnea, fatigue, mild non-productive cough, weight loss, and night sweats for one month. Initial chest X-ray (CXR) & computed tomography (CT) of the chest showed massive left-sided pleural effusion and pleural thickening & mildly enlarged mediastinal lymph nodes seen on CT. Thoracentesis with fluid studies and cytology demonstrated exudative lymphocytic predominant pleural effusion with PH less than 7, glucose 8, lactate dehydrogenase (LDH) >7000 U/L and occasional dysplastic cells with negative culture data. Given the high risk of atypical infection due to immunosuppression, the patient was started on broad-spectrum antibiotics without clinical improvement, which later was discontinued. A repeat CT chest showed re-accumulation of pleural effusion followed by repeat thoracentesis with chest tube placement and fluid studies showed PH 6.8, Glucose 21, adenosine deaminase (ADA) 97 U/L, and rare reactive mesothelial & atypical cells on cytology. Gram stain, acid-fast bacillus stain, and culture remained negative. The unclear etiology of recurrent left pleural effusion in the absence of obvious infection prompted pleural decortication via video-assisted thoracic surgery (VATs) with pleural biopsy and chemical pleurodesis showed PSC with high PD-L1 expression. chemotherapy started given the lack of surgical candidacy, but the patient, unfortunately, had progressive deterioration of his health with rapid progression of malignancy leading to death. DISCUSSION: Our patient was diagnosed with PSC notoriously associated with a poor prognosis due to rapid progression and profound heterogeneity leading to a very high rate(70.6%)of misdiagnosis on cytology and sometimes biopsy specimens. The presence of ongoing immunosuppression, and indolent yet short-period symptomology led to a presumptive diagnosis of an atypical infection possibly causing empyema in our patient. Fluid studies reflective of low PH, and low glucose in cases of MPE as in our case is an important prognostic indicator,3 and a broad differential should be considered to prevent diagnosis delay. A systemic approach to diagnosing pleural effusion of unknown etiology led to a diagnosis. CONCLUSIONS: PSC is a rare malignancy that can present with indolent symptoms and rapid progression leading to poor prognosis, as in our patient's case. Early recognition and treatment are crucial for curative surgery and adjuvant treatment to improve survival. REFERENCE #1: Li X, Wu D, Liu H, Chen J. Pulmonary sarcomatoid carcinoma: progress, treatment, and expectations. Therapeutic Advances in Medical Oncology. 2020;12:175883592095020. doi:10.1177/1758835920950207 REFERENCE #2: Pelosi G, Melotti F, Cavazza A, et al. A modified vimentin histological score helps recognize pulmonary sarcomatoid carcinoma in small biopsy samples. Anticancer Res. Apr 2012;32(4):1463-73. REFERENCE #3: Aydin Y, Turkyilmaz A, Intepe YS, Eroglu A. Malignant pleural effusions: appropriate treatment approaches. Eurasian J Med. Dec 2009;41(3):186-93 DISCLOSURES: No relevant relationships by Aaisha A Shah No relevant relationships by Ahmad Alhajhusain No relevant relationships by Chelsea Ledgerwood No relevant relationships by Adeel Nasrullah No relevant relationships by Shivani Shah No relevant relationships by Shiza Virk