Q & A
Q. The reference diagnosis from an aspiration biopsy of the lung is squamous cell carcinoma. Shouldn’t this smear be classified as unsatisfactory due to obscuring inflammation? We did not see malignant cells.
A. The slide in question is from a cavitary lung lesion in a 55-year-old man. There is a heavy inflammatory background with necrotic debris as well as fungal hyphae. If you stop at this point and assume that you have found the cause of the lung cavity, you will have fallen into a classical cytology trap. Indeed, the cause of the cavity is a squamous cell carcinoma, which can be recognized by careful review. The error can be avoided by systematically evaluating each slide for adequacy, organisms, and cellular abnormalities. No specimen can be categorized as "unsatisfactory" if there are tumor cells, regardless of number.
1. Neal MH, Kline TS. Distraction index: Part I—the elusive trich. Diagn Cytopathol. 1999;21:367-369.
2. Schulte, MA. Distraction index: Part II: inflammation in nongynecologic cytology. Diagn Cytopathol. 2000;23: 149-150.
Mike Schulte, MD
Department of Pathology
St. Michael Hospital