Cytologic diagnosis and ultrastructure of fine-needle aspirates of ganglion cysts.

This report describes 28 ganglion cysts in 21 patients. The presence of a colorless to pale-yellow gelatinous material in the aspirate is pathognomonic of ganglion cyst. The smears are fairly monotonous, and show abundant mucoid material, single cells resembling histiocytes, a few tight clusters of cells, some collagen fibers, and some red blood cells with altered shapes. Ultrastructural studies performed on five specimens reveal the fibroblastic and/or histiocytic nature of the cells in the aspirates.