Abstract

Granular cell tumor is characterized by large eosinophilic cells with granular appearances. These are mostly benign. Approximately 1~2% are malignant, and establishment of reliable criteria for diagnosing malignant granular cell tumor has been difficult to establish because of the rarity. Reports on the cytologic features of this neoplasm are hardly found in Korea. We report a case of rarely-occurring granular cell tumor in the lower leg of a 40-year-old male, diagnosed on fine needle aspiration cytology, together with a review of the literature regarding significant adverse histology and prognostic factors. The aspirates revealed cellular smears of isolated cells, syncytial clusters, and occasionally stripped nuclei in a fine, bluish-purple, granular background. Tumor cells were polygonal, rounded, or slightly spindled, and showed ill-defined granular cytoplasm. Nuclei were small and round or oval, with inconspicuous or small, prominent nucleoli. The nuclei showed rare intranuclear cytoplasmic invagination. Occasionally, there were mild to moderate nuclear pleomorphisms with vesicular nuclei, with large, prominent nucleoi, but no mitosis. The immunocytochemical stain for S-100 was strongly positive in the cytoplasm of tumor cells with occasional nuclei.

• Keywords: Granular cell tumor;Fine needle aspiration;Lower leg;Malignant granular cell tumor