A rare case of a giant pulmonary solitary fibrous tumor: Diagnostic and therapeutic challenges in the absence of malignancy.

Background: Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms predominantly arising from the pleura but occasionally occurring in extrapleural locations. Pulmonary parenchymal SFTs of extreme size are exceedingly uncommon and present diagnostic and therapeutic challenges. Case presentation: We report the case of a 60-year-old female with a 14 x 12 × 23 cm pulmonary SFT presenting with a two-week history of productive cough and significant weight loss. Imaging revealed a massive heterogeneous mass in the left lower lobe, compressing lung parenchyma, causing pleural effusion and atelectasis, and raising concerns for metastatic spread to the liver and spleen. Histological examination confirmed the diagnosis of SFT, with spindle-cell morphology and positive immunohistochemical staining for CD34 and STAT6. Despite the tumor's size and compressive effects, histopathology showed no necrosis, pleomorphism, or high mitotic activity, indicative of a non-aggressive phenotype. The patient underwent successful surgical resection via thoracotomy and is under long-term follow-up. Discussion: This case highlights the unique diagnostic complexity of SFTs, particularly with tumors of exceptional size. While larger SFTs often suggest malignant potential, the absence of typical markers of malignancy in this case emphasizes the unpredictable behavior of these tumors. Imaging and immunohistochemical evaluation are critical for diagnosis, and surgical resection remains the cornerstone of management. Conclusion: This rare case underscores the importance of thorough diagnostic evaluation and surgical management in addressing giant pulmonary SFTs. Despite their potential for malignant transformation, careful histopathological analysis and multidisciplinary collaboration can guide optimal treatment and long-term surveillance for these unpredictable tumors.