Abstract Introduction Small cell lung cancer (SCLC) is an aggressive neuroendocrine malignancy that typically arises centrally and is strongly associated with smoking. SCLC presenting as a solitary pleural-based mass is exceedingly rare and can mimic mesothelioma or metastatic disease, posing a diagnostic challenge. Early identification and accurate staging are critical, as limited-stage disease is potentially curable with combined chemoradiation. Case Report A 42-year-old woman with no significant medical history presented with several weeks of intermittent right-sided chest pain radiating to the flank and axilla. The pain was non-pleuritic and not associated with cough, dyspnea, fever, or weight loss. She denied trauma, smoking, or occupational exposures, and had no significant family history of malignancy. Physical examination was unremarkable, with normal breath sounds and stable vital signs, including oxygen saturation of 100% on room air. Chest X-ray revealed a 4.4 cm right pleural opacity. CT chest confirmed a 3.7 × 2.6 cm lobular pleural-based mass without adenopathy or effusion. CT-guided biopsy showed small cell neuroendocrine carcinoma with extensive necrosis; immunohistochemistry demonstrated synaptophysin + / CD56 + / TTF-1 - / p40 - / pancytokeratin -, consistent with extrapulmonary/pleural origin. PET/CT demonstrated an FDG-avid right pleural mass (SUVmax 11.3, 5 × 3.6 cm) with no nodal, distant, or osseous disease, and MRI brain was negative for metastasis. The case was reviewed in a multidisciplinary tumor board meeting and staged as limited-stage (Stage IIB) SCLC. The patient also carried the alpha-1 antitrypsin PiMS genotype without clinical deficiency. Treatment was initiated with concurrent cisplatin-etoposide chemotherapy and thoracic radiation, followed by 12 months of durvalumab consolidation per guidelines. A mediport was placed, and genetic counseling was offered due to family cancer history. The patient tolerated therapy well and remains clinically stable. Discussion This case illustrates an uncommon presentation of SCLC confined to the pleura in a young, low-risk female. The atypical location mimicked other pleural malignancies, emphasizing the importance of tissue diagnosis and immunohistochemistry for accurate classification. Comprehensive staging with PET/CT and brain MRI confirmed limited-stage disease, allowing timely initiation of curative-intent chemoradiation followed by durvalumab. This case underscores the necessity of early multidisciplinary evaluation and awareness of rare SCLC variants to ensure appropriate management and improve outcomes. This abstract is funded by: None
Moin et al. (Fri,) studied this question.