A case of alveolar soft part sarcoma of the pleura

Abstract

Alveolar soft part sarcoma (ASPS) is a rare malignant soft-tissue neoplasm of unknown histogenesis. The two main sites of occurrence are the lower extremities in adults and the head and neck in children. We report the first case of pleural ASPS occurring in a 58-yr-old man who presented with progressive dyspnea. A computed tomographic scan of the thorax revealed a large enhancing pleural mass with pleural effusion in the left hemithorax. Wide excision of the pleural mass was performed. Histologically, the tumor consisted of organoid nests of large polygonal cells, the cytoplasm of which had eosinophilic and D-PAS positive granules. Immunohistochemical staining showed that the tumor cell nuclei were positive for transcription factor 3 (TFE3). The pleural ASPS with multiple bone metastases recurred 1 yr after surgery and the patient died of acute pulmonary embolism 1.5 yr after diagnosis.

Keywords: Alveolar Soft Part Sarcoma; Pleura.

Fig. 1

Chest X-ray and chest computed tomography (CT) at admission. (A) Chest X-ray showing a large pleural effusion in the left hemithorax. (B-D) Chest CT, showing a huge pleural mass with pleural effusion in the left hemithorax (B), a pulmonary nodule in the left upper lobe (C, arrow), and a right pleural nodule (D, arrow).

Fig. 2

Positron emission tomography-computed tomography (PET-CT) scans. (A) A focal hypermetabolic nodular lesion is seen in the left upper lobe. (B) A large pleural effusion with heterogeneous minimal-to-mild hypermetabolic activity is seen in the left lower lobe. (C) Minimal hypermetabolic nodular lesion is seen in right lower pleural surface (arrow). No other hyperrmetabolic lesions suggesting a primary tumor are seen in this PET-CT image.

Fig. 3

Light microscopy features of the resected pleural and renal tumors. The renal tumor was resected in another hospital 20 yr previously and diagnosed as a low-grade clear cell renal cell carcinoma. (A) The pleural tumor shows an organoid or nesting arrangement of cells with a pseudoalveolar pattern. The tumor cells are separated by fibrovascular septa and delicate capillary-sized vascular channels (H&E, × 200). (B) The cytoplasms of the tumor cells are D-PAS positive (D-PAS, × 200). (C) Immunohistochemistry of the pleural tumor. The nuclei are positive for TFE3 (TFE3, × 400). (D) The tumor cells of right renal mass have clear cytoplasms, distinct cell borders, and small nuclei. The cells are arranged in small solid nests (H&E, × 200).

Fig. 4

Electron micrograph, showing cells containing numerous mitochondria, prominent rough endoplasmic reticulum, well-developed Golgi complexes, and many membrane-bound electron-dense granules.