FINE-NEEDLE ASPIRATION BIOPSY DIAGNOSIS OF A GASTROINTESTINAL STROMALTUMOR UTILIZING TRANSMISSION ELECTRON-MICROSCOPY

BACKGROUND: Gastrointestinal stromal tumors are spindle cell tumors wi th no specific cell lineage occurring in the gastrointestinal tract an d cytologically resemble other benign and malignant spindle cell rumor s. Distinctive ultrastructural features in some of these tumors have n ot been previously emphasized. CASE: A 76-year-old, white female prese nted with multiple tumor masses distributed in the large bowel. Fine n eedle aspiration biopsy demonstrated a cellular aspirate composed of s pindle cells, some of which were loosely arrayed and some of which wer e in cohesive clusters. Many of the cells contained long cytoplasmic p rocesses. Ultrastructurally the cells demonstrated long cytoplasmic pr ocesses upon which multiple shorter, fingerlike projections arose. Sub sequent surgical resection confirmed the cytologic and ultrastructural findings. CONCLUSION: Electron microscopy has a role to play in the d iagnosis of gastrointestinal stromal tumors.