Diagnostic pitfalls of infarcted Warthin tumor in frozen section evaluation

• FNA may lead to ischemic injury resulting in the infarction of WT.
• Infarcted WT may demonstrate variable gross and histologic alterations that may render the diagnosis challenging at the time of frozen section evaluation.
• The histologic findings of infarcted WT include necrosis, ghosts of papillae, squamous metaplasia, cholesterol clefts, foamy macrophages, multinucleated giant cell reaction, necrotizing granulomas, and fibrosis.
• Potential pitfalls in the diagnostic consideration of infarcted WT include squamous cell carcinoma, mucoepidermoid carcinoma, lymphoepithelial cysts, and chronic sialadenitis.

Warthin tumor (WT) is the second most common benign salivary gland neoplasm and has characteristic cytologic and histologic findings. Fine-needle aspiration is a common and useful preoperative diagnostic technique, which sometimes leads to ischemic injury resulting in the infarction of these lesions. Infarcted WT may demonstrate variable gross and histologic alterations that may render the diagnosis challenging, particularly during intraoperative frozen section evaluation.In this study, we collected 11 resection specimens from 9 patients with infarcted WT. Seven patients were men and 2 were women, ranging from 49 to 85 years (mean, 69). All the patients had fine-needle aspiration before the resection. Macroscopically, the tumors were tan-white and contained soft, yellow, exudative material. The histologic findings were variable and included necrosis, ghosts of papillae, squamous metaplasia, cholesterol clefts, foamy macrophages, multinucleated giant cell reaction, necrotizing granulomas, and fibrosis. Each case predominantly demonstrated 1 or 2 of these histomorphologic features. In the permanent sections, additional sampling revealed foci of residual viable WT in 8 cases. Three cases were completely infarcted; however, they all had ghost-like papillae in which the architecture of WT was evident.Infarcted WT may present a diagnostic challenge during intraoperative frozen section evaluation. Associated morphologic alterations may preclude a definitive diagnosis of WT and may mimic malignancy. Awareness of the gross and microscopic features associated with infarcted WT is important, particularly for accurate frozen section evaluation of these salivary gland tumors.