Title : The wandering mass: A case of solitary fibrous (spindle cell) tumor of the pleura
Abstract:
Background: Solitary Fibrous Tumor (SFT) of the pleura is a rare mesenchymal neoplasm arising from sub mesothelial connective tissue and accounts for less than 5% of pleural tumors. Although typically slow-growing and often incidentally detected, SFT may progressively enlarge, cause symptoms from mass effect, and demonstrate malignant potential. Diagnosis relies on histopathologic examination and characteristic nuclear stat6 immunoreactivity, while complete surgical resection remains the mainstay of treatment.
Case presentation: We report the case of an 83-year-old woman with a 21-year history of a right-sided thoracic mass initially discovered during evaluation for dry cough. Initial imaging revealed a 4.8 × 6.1 × 3.2 cm right apical mass. Biopsy was initially declined, and conservative management was pursued due to minimal symptoms. Serial imaging over the years demonstrated gradual enlargement, reaching approximately 7.7 × 7.8 × 7.2 cm, with prolonged periods of clinical stability. However, the patient eventually developed persistent dry cough, intermittent exertional dyspnea, and unintentional weight loss. Subsequent imaging revealed a large pleural-based mass measuring approximately 13 × 7.9 × 13.4 cm, associated with pleural effusion and an apparent change in intrathoracic location from the right upper to lower lung field. Biopsy demonstrated a spindle cell neoplasm consistent with SFT, with immunohistochemistry positive for stat6, cd34, bcl-2, and cd99,and negative for cytokeratin. The patient underwent Video-Assisted Thoracoscopic Surgery (VATS) with en-bloc tumor excision and right middle lobe wedge resection. Histopathology revealed a 15.5 cm spindle cell tumor with characteristic pattern less architecture, prominent staghorn vasculature, and low mitotic activity. Tumor necrosis was present, but surgical margins were negative.
Conclusion: This case illustrates the indolent yet unpredictable behavior of pleural SFT, characterized by prolonged clinical stability followed by significant interval growth and symptomatic progression. The unusual apparent change in tumor location highlights the possibility of a mobile, pedunculated pleural mass, which may complicate radiologic assessment. SFT should be considered in the differential diagnosis of slowly enlarging pleural-based lesions. Histopathologic confirmation, multidisciplinary evaluation, and complete surgical resection are essential. Given the potential for very late recurrence, prolonged and potentially lifelong surveillance is warranted.
