Abstract

BACKGROUND
Alveolar soft part sarcoma (ASPS) accounts for 0.5-1% of soft tissue sarcomas, and often metastasizes to the lung. Cases of pulmonary ASPS of unknown primary site have rarely been reported in literature.
METHODS
Here, we report three cases of metastatic pulmonary ASPS and three cases of presumably primary ASPS using immunohistochemistry and clinicoradiologic findings.
RESULTS
All of the cases occurred in young females. Two of the cases had metastasized from soft tissue ASPS of the lower extremities, and one case had metastasized from one of the patient? femur bones. Immunohistochemical stains were applied to four cases that had available paraffin blocks. The tumor cells of all cases on which immunohistochemical stains were done were positive for vimentin (4/4, 100%). None of the tumors were positive for myoglobin, desmin, smooth muscle actin, progesterone receptor, estrogen receptor, thyroid transcription factor-1, S-100 protein, pancytokeratin, and HMB-45 antibodies.
CONCLUSION
The present study revealed that the rare pulmonary ASPS has nonspecific clinicoradiologic findings. In the immunohistochemical results, no differences existed between the presumably primary ASPS and the metastatic ASPS except for a higher Ki-67 labeling index in the latter (less than 0.1% vs. 30%). The higher index was not dissimilar to those of the extrapulmonary ASPS which showed a tumor with a low proliferation index, signifying a better prognosis and have a low potential to metastasize.