Ewing's sarcoma (ES)/PNET is common in both axial and appendicular skeletons, but is extremely rare in the talus. Here, we report a case of ES/PNET of the left talus in a 29-year-old male patient diagnosed by fine needle aspiration cytology, and review the literature on similar cases. The cytological smears were composed of individually dispersed small round cells and occasional clusters of loosely cohesive cells. The tumor cells were fragile, frequently exhibiting naked nuclei. Two distinct types of cells were observed. The light (chief) cells displayed round or slightly oval nuclei with frequent indentations, generally inconspicuous nucleoli, and a thin rim of cytoplasm, which sometimes harbored small vacuoles. The dark cells were smaller, displaying scanty cytoplasm with dense hyperchromatic nuclei, intermixed with chief cells, and often manifesting as small molded groups. However, no significant nuclear pleomorphisms or mitoses were noted. Tumor cells in the cell block revealed positive cytoplasmic glycogen, as determined by a PAS stain with diastase control, and also exhibited positive immunoreactivity for CD99.
Adult ; Amylases ; Biopsy, Fine-Needle ; Cytoplasm ; Fungi ; Glycogen ; Humans ; Male ; Mitosis ; Sarcoma, Ewing ; Skeleton ; Talus* ; Vacuoles

Neuromuscular choristoma is a rare benign tumor of the peripheral nerves. To the best of our knowledge, 21 cases have been reported to date. We describe here a 20-day-old female infant who presented with a buttock mass (4.5 x 4.1 x 3.2 cm on MRI) arising from the left sciatic nerve. Microscopically, it was characterized by an intimately disorganized mixture of nerve fibers and striated muscle fibers that were occasionally surrounded by the perineurium and separated by fibrous bands of varying thickness. In some areas, there appeared to be some cells in transitional forms between nerve fibers and muscle fibers, revealing variously positive expressions for S-100 protein in the muscular components. These findings are consistent with the hypothesis that neuroectodermal-derived Schwann cells can give rise to mature skeletal muscle. It appears that the fibrosis may be related to the degeneration of the neural components. The size of the mass on MRI has been unchanged during the 3-year follow-up period.
Buttocks ; Choristoma* ; Female ; Fibrosis ; Follow-Up Studies ; Humans ; Infant ; Magnetic Resonance Imaging ; Muscle, Skeletal ; Muscle, Striated ; Nerve Fibers ; Peripheral Nerves ; S100 Proteins ; Schwann Cells ; Sciatic Nerve*

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.
Adult ; Biopsy, Fine-Needle* ; Cytoplasm ; Eosinophils ; Granular Cell Tumor* ; Humans ; Korea ; Leg* ; Male ; Mitosis