J Breast Cancer.  2019 Jun;22(2):336-340. 10.4048/jbc.2019.22.e17.

Human Epidermal Growth Factor Receptor 2-positive Mucinous Carcinoma with Signet Ring Cell Differentiation, Which Showed Complete Response after Neoadjuvant Chemotherapy

• Jang Y
• Cho EY
• Cho SY

• KMID: 2450126
• DOI: http://doi.org/10.4048/jbc.2019.22.e17

Abstract

Mucinous carcinoma (MC) is a rare subtype of breast cancer, which is composed of tumor cells floating in the abundant extracellular mucin. This form of cancer is usually estrogen receptor/progesterone receptor positive and human epidermal growth factor receptor 2 (HER2) negative. Here, we present a case of HER2-positive MC with an unusual signet ring cell differentiation. It is very rare that a breast tumor consists entirely of signet ring cells. The tumor showed pathologic complete response (pCR) after neoadjuvant chemotherapy with trastuzumab and pertuzumab. pCR of HER2-positive MC has rarely been described in literature. It is important to consider the biological heterogeneity of MCs for effective management.

Keyword

Breast neoplasms; Receptor, ErbB-2; Adenocarcinoma, mucinous; Neoadjuvant therapy; Carcinoma, signet ring cell

MeSH Terms

Adenocarcinoma, Mucinous
Breast Neoplasms
Carcinoma, Signet Ring Cell
Cell Differentiation*
Drug Therapy*
Epidermal Growth Factor*
Estrogens
Humans*
Mucins
Neoadjuvant Therapy
Polymerase Chain Reaction
Population Characteristics
Receptor, Epidermal Growth Factor*
Receptor, ErbB-2
Trastuzumab
Epidermal Growth Factor
Estrogens
Mucins
Receptor, Epidermal Growth Factor
Receptor, ErbB-2
Trastuzumab

Figure

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  Figure 1 Magnetic resonance imaging and microscopic findings before neoadjuvant treatment. (A) Axial T2-weighted image shows a well-enhanced mass in the right breast. (B) Core biopsy specimen shows tumor cell clusters floating in extracellular mucin pools (hematoxylin and eosin, magnification × 40) (C) Tumor showed extensive signet ring cell differentiation with high grade nuclear features, frequent mitosis, and tumor necrosis (hematoxylin and eosin, magnification × 400) (D, E, F). Tumor cells were negative for ER (D), positive for HER2 (E), and focally expressed GCDFP-15 (magnification × 200). ER = estrogen receptor; HER2 = human epidermal growth factor receptor 2; GCDFP-15 = gross cystic disease fluid protein 15.

• 

  Figure 2 Magnetic resonance imaging and microscopic findings after neoadjuvant chemotherapy with trastuzumab and pertuzumab. (A) T2-weighted imaging shows a mass showing cystic change. (B) Surgical specimen reveals only mucin pools with no viable tumor cells (hematoxylin and eosin, magnification × 200).

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