Abstract Introduction Solitary Fibrous Tumors (SFTs) of the pleura are exceedingly rare mesenchymal neoplasms with an estimated incidence of fewer than one case per million people annually, and account for less than 5% of all primary pleural tumors. Their rarity, diagnostic mimicry, and gaps in clinical research often lead to delayed diagnosis and inappropriate management. Case Presentation Here we describe a case of an 82-year-old-male with a history of atrial fibrillation and hypertension who presented with progressive dyspnea on exertion. He denied fevers, chills, weight loss, chest pain, cough, hemoptysis, orthopnea, paroxysmal nocturnal dyspnea or lower extremity edema. Initial imaging showed a right pleural effusion. Post-thoracentesis CT chest with contrast showed a right upper lobe heterogeneous 6.0 x 4.4 cm mass at the right paratracheal/pleural margin. Pleural fluid cytology suggested mesothelioma given the calretinin positivity. A biopsy specimen was subsequently obtained via robotic assisted bronchoscopy. Histopathological analysis showed spindle cells arranged haphazardly which is seen in sarcomatoid type mesothelioma. Immunohistochemical staining was strongly positive for STAT6 and CD34, which ultimately confirmed the diagnosis of pleural SFT. He was referred to thoracic surgery for surgical resection with close pulmonology follow-up. Discussion This case highlights the diagnostic challenges of pleural SFTs, which can clinically, radiographically, and histologically mimic mesothelioma. The histological diversity of SFTs and rare calretinin positivity can lead to misdiagnosis. Immunohistochemical staining is therefore essential to obtain an accurate diagnosis. Furthermore, their indolent growth, and late presentation often results in larger disease burden and higher metastatic potential. Surgical resection remains the cornerstone of management of local disease, while the efficacy of radiation and chemotherapy require further investigation. Conclusion Pleural SFTs, though exceedingly rare, should remain in the differential diagnosis for pleural-based masses. Awareness of their potential to clinically, radiographically, and histologically mimic mesothelioma can prevent misdiagnosis and inappropriate treatment. Prompt immunohistochemical evaluation and surgical resection are essential for optimal outcomes, followed by vigilant surveillance due to their risk of recurrence. This abstract is funded by: None
Le et al. (Fri,) studied this question.