Synovial sarcoma metastatic to the parotid gland: A possible pitfall in salivary gland fine needle aspiration cytology. Report of a case with immunocytochemical and fluorescence in situ hybridization findings

Synovial sarcoma: cytopathology of 51 cases highlighting the application of ancillary molecular testing

INTRODUCTION

Among sarcomas, synovial sarcoma (SS) is defined by its unique SS18 cytogenetic translocation. Fine needle aspiration (FNA) biopsy is in a key position to exploit this uniqueness for diagnostic purposes.

MATERIALS AND METHODS

Our cytopathology files were searched for examples of SS with histopathologic verification. FNA biopsy, imprint smears, and core needle biopsy (CNB) were performed using standard techniques.

RESULTS

Fifty-one cases from 49 patients (male/female ratio, 1:1; age range, 12-79 years; mean age, 40 years) met the inclusion criteria. Of the 51 cases, 44 (86%) were FNAs, 6 were cytology imprints, and 1 was pleural fluid. Eleven aspirates had concurrent CNB. All cases had tissue confirmation. The biopsy sites included extremities (n = 24; 47%), trunk (n = 12; 24%), lung (n = 8; 16%), head or neck (n = 6; 12%), and pleural fluid (n = 1; 2%). The aspirates were from primary (n = 36; 71%), metastatic (n = 12; 24%), and recurrent (n = 3; 5%) neoplasms. The cytologic diagnoses were SS (69%), suspicious for SS (12%), malignancy (10%), spindle cell neoplasm (4%), and malignancy other than SS (6%). In general, smears and imprints contained dense cell aggregates and single cells composed of a monotonous population having fusiform, rounded, or ovoid banal nuclei and scant cytoplasm. Poorly differentiated SS showed both large epithelioid cell and small cell cytomorphology. When performed, SS18 immunohistochemical and genetic testing was positive in all 19 FNA and 3 CNB cases.

CONCLUSIONS

When coupled with appropriate ancillary testing, FNA biopsy allows for a specific, accurate diagnosis of SS in most cases.

Mesenchymal neoplasms of the parotid gland and parapharyngeal space: an FNA cytologic study of 22 nonlipomatous tumors

BACKGROUND

Mesenchymal neoplasms of the parotid gland (PG) and para-pharyngeal (PP) space are distinctly uncommon. Fine-needle aspiration (FNA) biopsy experience with nonlipomatous neoplasms from this site is reviewed.

METHODS

Cytopathology and surgical pathology files were examined for mesenchymal PG and PP space neoplasms. FNA biopsy was performed using standard technique.

RESULTS

Twenty-two PG and/or PP aspirates from 20 adults (male:female = 1.1:1; age range, 19-84 years, mean age, 50 years) and a 10-week-old infant met inclusion criteria. Biopsy sites included PG (17, 77%) or PP space (5, 23%). Five of 6 malignant neoplasms (83%) were called malignant cytologically. Only 7 of 11 (63%) benign neoplasms were recognized as a benign neoplasm. None of 5 solitary fibrous tumor (SFT) cases were correctly recognized. Conversion to the Milan classification showed 8 (36%) FNA cases diagnosed as benign neoplasm, 6 (27%) malignant neoplasm, 4 (18%) neoplasm of uncertain malignant potential, 2 (9%) nondiagnostic, and single cases of suspicious for malignancy and nonneoplastic. There was 1 false-positive and no false-negative FNA diagnoses. Ancillary testing in 10 (45%) aspirates helped substantiate a correct specific diagnosis in 3 malignant and 3 benign cases.

CONCLUSIONS

FNA biopsy of nonlipomatous mesenchymal SG neoplasms is particularly challenging. Less than half (9 of 11, 41%) had specific FNA diagnoses that correctly matched the tissue diagnoses or clinical outcome. Accurate Milan categorization was superior for malignant neoplasms (5 of 6, 83%) in contrast to benign neoplasms (7 of 11, 63%), or neoplasms of uncertain malignant potential (SFT) (2 of 5, 40%).