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Chapter 11

Subclassification of DCIS to distinguish between com- edo and noncomedo variants may be suggested by FNA cytology. 258–260 The aspirate from “comedo”-type, that is, solid-type DCIS with high nuclear grade, typically consists of pleomorphic, loosely cohesive cells with poorly differen- tiated nuclei and prominent nucleoli, sometimes accompa- nied by mitotic figures. Necrotic debris that may contain calcifications is usually present. Specimens from noncom- edo DCIS tend to contain more cohesive three-dimensional cell clusters with a papillary or cribriform configuration, as well as dispersed cells distributed singly or in small groups (Fig. 11.64). Nuclei are intermediate to low grade cytologi- cally, and they usually lack prominent nucleoli. Necrosis and an inflammatory cell background are found much less often in aspirates from noncomedo DCIS. Although the foregoing cytologic features may be reliable for distinguishing between classic examples of lesions such as solid-type DCIS with high nuclear grade and orderly crib- riform DCIS, there are circumstances in which the findings are not clear. This can occur when the intraductal carcinoma has nuclei of variable grade nuclei.

Extent of DCIS The extent of DCIS ranges from one duct or 0.1 cm to widespread involvement of multiple quadrants of the breast. 261 Although exact determination of the extent of DCIS may be “a wild goose chase,” 262 estimation of its di- mension is significant for management purposes. The size of DCIS can be accurately assessed by measuring micro- scopic extent only when it is present on a single slide. 263 Estimating the size of DCIS from the radiologic extent of cal- cification or by recording the number blocks can result in ei- ther overestimation or underestimation, particularly in cases where the sections are not taken consecutively. It has been suggested that assessment of DCIS using the block method underestimates size with a mean reduction of 33%. In a study of 33 patients with a histologically proven DCIS by needle biopsy, the mean lesion size was 25.6 his- tologically, 28.1 mm by MRI, and 27.2 mm on mammog- raphy. The correlation coefficient between histopathologic measurement and MRI was 0.831 versus 0.674 between his- topathology and mammography. The correlation coefficient

C

D

FIG. 11.64.  DCIS, cribriform, cytology. A: Irregular flat sheet of cells with a microlumen in an FNA smear. B: Three adjacent microlumens are apparent in the epithelium with low-grade nuclear ­cytology. C,D: Epithelial clusters with low-grade nuclei on ThinPrep (C) and on Diff-Quik stain (D) .