The cytopathology of soft tissue mxyomas - Ganglia, juxta-articular myxoid lesions, and intramuscular myxoma

We studied the practicality of issuing a cytologic diagnosis of myxoma/juxta-articular myxoid lesion/ganglion (MJG) by reviewing all fine-needle aspiration (FNA) biopsy specimens of soft tissue masses in our files with diagnoses of myxoma, myxoid cyst, myxoid lesion, ganglion, or ganglion cyst. The control group was soft tissue aspirates with abundant myxoid stroma. Of 39 cases with a cytologic diagnosis of soft tissue MJG, 15 had subsequent tissue biopsy or complete resection of the mass; 24 had clinicoradiologic follow-up. All cases except 1 (fat necrosis) were diagnosed correctly as benign myxoid lesions. We grouped MJG aspirates into 3 subtypes based on clinicoradiologic features: soft tissue ganglion/ganglion cyst (12 cases), juxta-articular myxoid lesion (16 cases), and intramuscular myxoma (11 cases). MJG aspirates showed few, subtle cytopathologic differences among subtypes. They characteristically had a viscous, gelatinous quality when expressed from the needle onto the glass slide. The typical smear contained a film of paucicellular often finely granular, myxoid stroma that contained few cells, usually macrophages or bland spindle cells. Control group aspirates always contained cellular components that allowed distinction from MJGs. The cytopathologic diagnosis of MJG lesions is accurate; FNA biopsy can be used to subtype MJGs into 3 categories when clinicoradiologic features are known.