A case of alveolar soft part sarcoma of the larynx

Background: Alveolar soft part sarcoma is a rare tumor, accounting for less than 1% of all primary soft tissue malignant tumors. This tumor has a characteristic morphologic feature, but its histogenesis is controversial. A case of alveolar soft part sarcoma of the larynx, an unusual primary site for this rare sarcoma, is reported. Case: A 34-year-old woman was found to have a submucosal tumor in the right vocal cord. The Papanicolaouand PAS-stained imprint cytology specimen obtained by incisional biopsy showed sheet-like and minimally cohesive clusters composed of tumor cells with abundant polygonalshaped cytoplasm. The tumor cells had large and round nuclei with one to a few prominent nucleoli. Intra-nuclear cytoplasmic pseudoinclusions were noted. The cytoplasm showed a granular appearance with Papanicolaou stain and contained PAS-positive granules, however, PAS-positive needle-shaped crystalloids were not identified. Histologically, the tumor showed the characteristic feature of alveolar soft part sarcoma. Immunohistochemical analysis revealed positive staining for vimentin, desmin, muscle specific actin, and α-smooth muscle actin. Ultrastructurally, the tumor cells possessed numerous mitochondria and spicular crystal crystalloid material. Conclusion: It is thought to be possible to distinguish alveolar soft part sarcoma from granular cell tumor, paraganglioma, oncocytoma, and metastatic renal cell carcinoma cytologically by the characteristic features of the cytoplasm and nucleus found in the PAS-stained specimens in addition to Papanicolaou-stained ones.