Desmoid tumors of the pleura: a clinicopathologic mimic of localized fibrous tumor.

Intrathoracic desmoid tumors of the pleura are unusual tumors that are often clinically and histologically confused with localized fibrous tumor of the pleura or benign neurogenic tumors. We studied four cases of intrathoracic desmoid tumor of the pleura and reviewed the clinical, histopathologic, and immunohistochemical features of the four patients. Two men and two women, ranging in age from 16 to 66 years (mean, 44 yr) comprised the study group. Three patients presented with chest pain and one with shortness of breath. Two patients had a history of associated trauma in the area of the tumor. Three of the lesions were based in the parietal pleura and one in the visceral pleura. Treatment included complete resection (two cases), subtotal resection (one case), and subtotal resection followed by radiation therapy and complete resection (one case). The mean tumor size was 12.5 cm, and all of the tumors exhibited a bosselated, firm, white, cut surface. The histologic features of intrathoracic desmoid tumors were similar to those of desmoid tumors at more conventional sites. Infiltration of the adjacent fat and skeletal muscle was invariably present. The tumor cells were immunoreactive for vimentin, desmin, smooth muscle actin, and muscle-specific actin in three of the four cases and were negative for S-100 protein. Follow-up to date shows stable residual disease at 12 months (one case) and two patients with no evidence of disease at 12 and 96 months, respectively. Intrathoracic desmoid tumors often exhibit clinical and radiographic features similar to localized fibrous tumor of the pleura. They generally have histologic and behavioral characteristics identical to those of desmoid tumors at conventional sites. Like desmoid tumors elsewhere, complete resection with negative margins is vital to prevent local recurrence. Desmoid tumor should be considered in the differential of localized fibrous tumor of the pleura.