Case 13

A 40-year-old female was found to have distortion on imaging of left breast, and a biopsy was obtained.

1. What's your interpretation:

   A: UDH with apocrine metaplasia

   B: Atypical apocrine adenosis

   C: Flat epithelial atypia

   D: Columnar cell change

   E: Classic DCIS, nuclear grade 1

   F: Micropapillary DCIS, nuclear grade 3

   G: Gynaecomastoid-type UDH

Answer

The correct answer is F, However, recognizing the presence of atypia is very important so B, C, E also get credits! In micropapillary DCIS, papillary fronds and tufts lacking fibrovascular cores projecting into duct lumen and always showed a thin base with big tips however, in gynaecomastoid-type UDH, it showed extensive epithelial hyperplasia with tapering tufts (pyramid-shaped micropapillae). UDH of the gynaecomastoid type lacks the nuclear uniformity of low-grade DCIS, and the nuclei are aligned along the micropapilla's periphery. FEA lacks advanced structure like micropapillae, papillae or bridging. Apocrine adenosis is a lobulocentric proliferation of benign glandular structures with abundant granular cytoplasm distorted by fibrosis like sclerosing adenosis with pink cytoplasm. Significant cytologic atypia (>3:1 size variation, mitotic activity) may lead us consider atypical apocrine adenosis.

Finally, the nuclei grading here is grade 3.

Nuclear grade:

• Low grade:

  • Monotonous, round nuclei with smooth contours, small size nuclei (size of normal ductal epithelial cell or 1 - 1.5 diameter of normal red blood cell)

  • Diffuse fine chromatin, absent or indistinct nucleoli, no or rare mitotic figures, necrosis is uncommon but does not preclude the diagnosis of low grade DCIS

• Intermediate grade:

  • Moderate pleomorphism, mild to moderate variability in nuclear size

  • Variably coarse chromatin, occasional nucleoli, infrequent mitoses, features in between low and high grade DCIS

  • Loss of monotony can mimic usual ductal hyperplasia

• High grade:

  • Prominent pleomorphism, large size nuclei (> 2.5 size of normal ductal epithelial cell)

  • Vesicular chromatin with irregular distribution, prominent nucleoli, frequent mitoses, comedo necrosis frequent but not required

References:

https://www.pathologyoutlines.com/topic/breastmalignantdcis.html

https://tumourclassification.iarc.who.int/chaptercontent/32/126

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD