Ultrasound-guided fine needle aspiration cytology of angiosarcoma of head and neck: a review of cytomorphologic features and discussion of diagnostic pitfall of aspiration cytology of vascular lesions.

Angiosarcoma is a rare malignant tumor of vascular origin (<2% of sarcomas). It represents <1% of all head-neck malignancies. A cytological diagnosis on fine needle aspiration (FNA) is extremely difficult. Most tumors yield a predominantly hemorrhagic aspirate with only rare neoplastic cells, a diagnostic pitfall of aspiration cytology of vascular lesions. An 81-year-old male, 2 years status post resection of a nasal tip angiosarcoma and adjuvant radiation therapy, presented to another institution with an enlarging left neck mass of 2 months duration. Outside FNA diagnosis of cyst was made. Patient was referred to our institution for a pathologist-performed ultrasound-guided FNA. Ultrasound examination revealed a hypoechoic cystic left neck mass. Direct smears showed blood with occassional single malignant spindled to epithelioid cells, with some cells showing "spider-leg" like cytoplasmic processes/projections and "tadpole/fiber" like morphology. Immunohistochemistry performed on cell block sections revealed the tumor cells to be positive for D2-40, CD31 and CD34, supported a diagnosis of regional recurrent angiosarcoma. Left neck dissection showed recurrent high-grade angiosarcoma infiltrating periparotid soft tissues and metastatic angiosarcoma involving multiple lymph nodes. A diagnosis of angiosarcoma on FNA samples can be challenging, as the aspirate may contain only rare tumor cells hidden in a background of abundant blood. Such cases require careful screening to avoid an incorrect diagnosis of inadequate or cyst contents. This short review highlights key cytomorphologic features of angiosarcoma, includes novel cytologic features of angiosarcoma which has not been described previously and also discusses challenges and diagnostic pitfalls of FNA of vascular lesions.