Fine-needle aspiration of spindle cell and mesenchymal lesions of the salivary glands.

Fine-needle aspiration (FNA) biopsy can accurately diagnose epithelial lesions of the salivary gland. Its role in the evaluation of salivary gland lesions containing a significant spindle cell component is less clear. We describe the cytologic features of 25 spindle cell lesions of the salivary gland and discuss the differential diagnosis and potential diagnostic pitfalls. Twenty-five aspiration smears (3.0%) containing a significant spindle cell or mesenchymal component were identified out of 844 salivary gland FNAs performed over a 5-year period. These aspiration smears were from 25 patients. The smears were classified into three categories: 1) reactive or inflammatory conditions, including one granulation tissue and four granulomatous sialoadenitis; 2) benign neoplasms, including one schwannoma, one fibromatosis, four lipomas, and nine pleomorphic adenomas; 3) malignant neoplasms, including one recurrent malignant fibrous histiocytoma (MFH), two metastatic melanomas, and two metastatic osteosarcomas. There was one false-negative biopsy. The metastatic desmoplastic malignant melanoma was initially interpreted as a reactive lymph node with fibrosis. A specific diagnosis was rendered in 21 (84%) cases. The schwannoma was diagnosed cytologically as benign spindle cell lesion, not otherwise specified (NOS), fibromatosis as an atypical cellular proliferation, and MFH as poorly differentiated malignant neoplasm. Salivary gland lesions with a significant spindle cell component are rarely encountered on FNA and constitute a heterogeneous group. A specific diagnosis can be rendered in the majority of cases by correlating clinical and cytologic findings.