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Case of the Month: October 2022

posted: October 31, 2022

59-year-old male with history of Hypertension who recently complained of cough and congestion. Chest X-ray and CT scan showed a 14 cm pleural based left lower lung lesion. He underwent left thoracotomy and resection of the left lesion. Pathology is shown below.

Gross Pathology
Figure 1
Figure 1
View Final Diagnosis
Final Diagnosis: Malignant Solitary Fibrous Tumor
Malignant solitary fibrous tumor (SFT) of the thorax is a rare tumor of fibroblastic/ mesenchymal origin. Most SFTs arises in the visceral pleura are usually asymptomatic and discovered incidentally but as many as 10% of them behave aggressively. Larger tumors can present with symptoms of cough and dyspnea as in this case. Histologically, most SFTs are well-circumscribed with uniform spindle cells with varying cellularity and staghorn vessels. The more aggressive ones shows increased mitotic activity, hypercellularity and couagulative necrosis. In general, risk stratification are preferred over anatomical staging for these aggressive ones. The risk stratification system is based on patient’s age, tumor size, and mitosis and tumor necrosis ( please see references below). This solitary fibrous tumor shows mainly spindle cell and focally epithelioid morphology with high mitotic rate up to (14 mitosis/10hpf) and numerous pleomorphic and large multinucleated giant cells.
  1. Demicco, E., Wagner, M., Maki, R. et al. Risk assessment in solitary fibrous tumors: validation and refinement of a risk stratification model. Mod Pathol 30, 1433–1442 (2017).
  2. England DM, Hochholzer L, McCarthy MJ. Localized benign and malignant fibrous tumors of the pleura. A clinicopathologic review of 223 cases. Am J Surg Pathol. 1989 Aug;13(8):640-58. doi: 10.1097/00000478-198908000-00003. Erratum in: Am J Surg Pathol 1991 Aug;15(8):818. PMID: 2665534.
  3. Reisenauer JS, Mneimneh W, Jenkins S, Mansfield AS, Aubry MC, Fritchie KJ, Allen MS, Blackmon SH, Cassivi SD, Nichols FC, Wigle DA, Shen KR, Boland JM. Comparison of Risk Stratification Models to Predict Recurrence and Survival in Pleuropulmonary Solitary Fibrous Tumor. J Thorac Oncol. 2018 Sep;13(9):1349-1362. doi: 10.1016/j.jtho.2018.05.040. Epub 2018 Jun 20. PMID: 29935303.

This case is contributed by Dr. Zaid Mahdi. Department of Pathology, Emory University Hospital