Metastatic Malignant Granular Cell Tumor in the Lymph Node: A Cytological Report With Immunocytochemical Analysis

Granular cell tumors (GCTs) are relatively rare, whereas malignant GCTs are extremely rare. This brief report describes a cytological case of metastatic malignant GCT in the lymph node with immunocytochemical analysis. A 77 years old Japanese female with a history of surgical resection for malignant GCT in the back 8 years earlier presented with swelling of the right neck. Intraoperative touch smear of the biopsy specimen of the neck lymph node showed the presence of clusters of polygonal neoplastic cells as well as single neoplastic cells containing rich granular cytoplasm and eccentrically located large round to oval nuclei in a background of granular material. Immunocytochemical analysis demonstrated that these neoplastic cells showed positivity for S-100 protein and SOX10, and negativity for Melan-A and HMB45. According to these findings, a cytodiagnosis of metastatic malignant GCT was made with consideration of her history. Histopathological analysis confirmed a metastatic malignant GCT. The present study indicates that immunocytochemical staining for S-100 protein and SOX10 combined with cytomorphological features might be useful for the cytodiagnosis of malignant GCT.