Fine-needle aspiration cytologic features of pseudovascular adenoid squamous-cell carcinoma of the lung.

Pseudovascular adenoid squamous-cell carcinoma (PASCC) is an epithelial malignancy with spindle-cell features that can mimic vascular neoplasms, particularly angiosarcoma, in its morphologic characteristics. There have been only a few surgical pathology reports of PASCC arising in the lung, skin, and breast. We describe the fine-needle aspiration (FNA) cytologic and histologic features of a pulmonary PASCC in a 66-yr-old man. The aspiration yielded individually scattered and syncytial fragments of malignant epithelioid-appearing cells with oval to spindle shapes, prominent nucleoli, and a finely vacuolated amphophilic cytoplasm. The core needle biopsy specimen displayed these same cells lining pseudoluminal spaces, with intervening bundles of fibroconnective tissue simulating a vascular neoplasm. The neoplastic cells stained positively with cytokeratin (AE-1/3), epithelial membrane antigen, and vimentin and were nonreactive with S-100, muscle-specific actin, CD31, CD34, and carcinoembryonic antigen. These cytologic, histologic, and immunocytochemical features supported a diagnosis of PASCC. To the best of our knowledge, this is the first report of the FNA cytologic features of this pseudovascular variant of adenoid squamous-cell carcinoma. This FNA case illustrates that the cytologic impression was more accurate and, in fact, that the histologic features of PASCC can be misleading. The correct identification of PASCC and its distinction from angiosarcoma has important clinical ramifications for treatment and prognosis. FNA cytologic examination with ancillary studies is a minimally invasive procedure that can distinguish PASCC from sarcomatous lesions. Diagn. Cytopathol. 1999;21:265-270.