Features

Architecture

• Variably cellular
• Parallel and interlacing bundles of spindle smooth muscle cells
• Single cells typically not present

Cellular features

• Typically uniform cells
• May have large pleomorphic multinucleated cells in atypical leiomyomas
• Abundant dense fibrillar cytoplasm
• May have cytoplasmic vacuoles

Nuclear features

• Elongated cigar shaped nuclei
• Paranucleolar cytoplasmic vacuoles indenting nuclear outline
• Fine granular chromatin
• Conspicuous nucleoli

Background

• May have myxoid/hyaline change
• May have cystic degeneration or calcification
• Mitosis/Necrosis not present

Ancillary studies

• Express SMA, actin, Desmin, vimentin; typically negative for cytokeratin, CD34, CD117, DOG1, S100

Reference

Barbazza R et al. Diagn Cytopathol. 1997 Apr;16(4):326-30.