A case of primary neuroendocrine breast carcinoma that responded to neo-adjuvant chemotherapy

Abstract

Primary neuroendocrine breast carcinoma (NEBC) is a very rare type of breast cancer. Two characteristic biomarkers, namely, CgA and Syn, should be immunohistochemically detected to diagnose NEBC. In this study, a 43-year-old woman with a large mass of 8.3 cm × 2.9 cm in her right breast was reported. The patient was pathologically diagnosed with NEBC after specific markers, including CgA and Syn, as well as few differential markers, such as CK7, ER, PR, C-erbB-2, NSE, and E-cadherin, were immunohistochemically detected. The patient showed a remarkable response to four cycles of neo-adjuvant chemotherapy (partial response based on RECIST criteria) and sequentially underwent modified radical mastectomy. Moreover, the diagnosis and treatment of NEBC based on this case and available related literature were discussed.

Keywords

neuroendocrine carcinoma / neo-adjuvant therapy / breast

Introduction

Neuroendocrine cancer is a type of malignancy rarely detected clinically and occurs mainly in the gastrointestinal tract; this type of cancer was first reported in 1963 [ 1]. Since then, additional cases have been sporadically reported [ 2– 4]. Neuroendocrine breast carcinoma (NEBC) is a very rare tumor and accounts for 1% of the total breast malignancies. According to the WHO classification, primary NEBC is defined as a group of breast cancers morphologically similar to neuroendocrine tumors from gastrointestinal tracts or lungs; moreover, NEBC contains>50% of the cancer cells expressing neuroendocrine tumor markers [ 5, 6].

Thus far, only six retrospective NEBC cases have been reported on the basis of the 2003 WHO criteria. NEBC is associated with more aggressive behavior, higher propensity for local and distant recurrence, and poorer prognosis than ductal carcinoma. However, the optimal treatment for primary NEBC is poorly known because of limited reports. In this study, a case of primary NEBC was presented, in which a remarkable response to adjuvant chemotherapy was observed. The diagnostic and therapeutic aspects of NEBC were also discussed on the basis of currently available studies.

Methods

Hematoxylin and eosin (H&E) staining

Formalin-fixed and paraffin-embedded tissue was sectioned, deparaffinized, and rehydrated in a series of xylene and ethanol baths. The slides were placed in hematoxylin solution for 5 min, transferred to 1% alcoholic hydrochloric acid for 5 s, and immersed in eosin solution for 1 min.

Immunohistochemistry (IHC)

Formalin-fixed and paraffin-embedded tissue was sectioned with a thickness of 4 μm for IHC. In brief, the sections were deparaffinized and rehydrated using gradients with high percentage of ethanol to distilled water. Endogenous peroxidase activity was blocked with 3% hydrogen peroxide for 20 min at room temperature. Antigen was retrieved by boiling the sections in 10 mM sodium citrate buffer (pH 6.0) for 15 min in a microwave. The sections were incubated with primary antibody overnight at 4 °C. Secondary antibody was incubated for 60 min at room temperature. The sections were then stained with diaminobenzidine tetra-hydrochloride and counterstained with hematoxylin. The antibodies of anti-estrogen receptor (ER, Kit-0012-2), progesterone receptor (PR, Kit-0013-2), CD56 (MAB-0256), C-erbB-2 (MAB-0198), chromogranin A (CgA, RMA-0548), cytokeratin 7 (CK7, MAB-0166), Ki-67 (Kit-005-2), neuron-specific enolase (NSE, MAB-0584), synaptophysin (Syn, RMA-0537), and p53 (Kit-0010-2) were purchased from Fuzhou Maixin Biotech, Fuzhou, China.

ER, PR, p53, and Ki-67 were immunostained in tumor cell nuclei; CgA, NSE, and Syn were immunostained in the cytoplasm. Moreover, CD56 and E-cadherin were immunostained in the membrane; CK7 was immunostained in the cytoplasm or membrane, and C-erbB-2 was immunostained in tumor cell membrane. Immunohistochemical scoring, which was in accordance with the ASCO/CAP guideline, was listed as follows: negative, no staining; 1+, faint incomplete staining; 2+, weak or moderate circumferential complete membrane staining>10% of tumor cells or strong complete circumferential membrane staining≤30% of tumor cells; and 3+, strong complete circumferential membrane staining>30% of tumor cells.

Results

Clinical findings

A 43-year-old female patient who complained a painless mass in the right breast for six months was hospitalized. No evident abnormality was detected in the shape of both breasts by physical examination. A segmented mass with a size of 8.0 cm × 2.5 cm exhibiting hard texture, clear border, smooth surface, and mobility was palpable in the outer quadrant of the right breast. Axillary and supraclavicular lymph nodes were not palpable.

The patient did not present positive medical history and family history of breast, colon, ovarian, or other cancers. Breast ultrasound results showed an irregular hypoechoic substantial mass with scattered faculae, light spots, and abundant blood supply. The size of the mass was 8.3 cm × 2.9 cm, and a part of the border was not well defined. Multiple enlarged lymph nodes and strip blood flow were observed in the right axilla. Mammogram results showed a lobulated lump with a size of 8 cm×3 cm and high-density shadow in the central region in the outer quadrant of the right breast. The lump displayed unclear contours and few punctated calcifications. Multiple enlarged lymph nodes were also detected, and the largest node measured approximately 1.8 cm in diameter (Fig. 1A). X-ray examination results did not show any abnormity in the lungs and bones; abdominal echography results did not show any abnormal changes in the liver, biliary system, and pancreas.

The patient diagnosed histologically with invasive carcinoma was subjected to core needle biopsy. The IHC results demonstrated 70% positivity for ER, 10% positivity for PR, negative for C-erbB-2, and 40% positivity for Ki-67.

Treatment and clinical outcome

The patient was diagnosed with cT3N1M0 IIIA and received four cycles of neo-adjuvant chemotherapy with TEC regime (75 mg/m² docetaxel, 80 mg/m² epirubicin, 500 mg/m² cyclophosphamide, once a day for three weeks). The maximum diameter of the tumor decreased from 8.3 cm to 3 cm; the Ki-67 proliferation index decreased from 40% to 10%. Mammography results showed that the tumor mass became smaller with a size of 2 cm × 1.5 cm and with more punctated calcifications; moreover, the lymph nodes became smaller also (Fig. 1B). The therapeutic response was evaluated as partial response with a 63.8% reduction in tumor size according to the RECIST criteria [ 7] (Fig. 1). Modified radical mastectomy was performed after four cycles of neo-adjuvant chemotherapy. The gross pathology of the resected specimen showed a soft gray-white mass with a size of 3 cm × 2 cm in the upper-outer quadrant of the right breast. No hemorrhage and necrosis was observed in the specimen. Moreover, three enlarged axillary lymph nodes of approximately 1 cm in diameter were found. The pathological staging based on AJCC was ypT2N1M0 IIB.

Microscopic findings

The tumor cells were arranged in solid nests and groups in an H&E-stained section. Slender fibrovascular stroma was evident in the areas surrounding the nests. The tumor cells were characterized by medium size, oval shape, abundant cytoplasm, slightly eosinophilic, and fine granules. Some tumor cells lacked the cytoplasm. Cell boundaries were not well defined. Mitotic rate was lower than 5/10 high-power fields. Histological grade was indexed as grade II (Fig. 2).

IHC

Post-operative specimens were immunohistochemically stained using routine diagnostic methods in the department of pathology. The immunohistochemical results were listed as follows (Fig. 3): positive ER (80%); negative PR; 2+ for C-erbB-2; positive Ki-67 (10%); positive E-cadherin (>70%); positive NSE (>50%); positive CgA (>50%); positive Syn (>50%); partially positive CK7; negative CD56; and positive P53 (15%).

Discussion

Primary NEBC usually does not show any specific finding on the mammogram of the breast compared with primary ductal-type breast cancer [ 8, 9]. The accurate diagnosis of NEBC relies on the results of pathology and immunohistochemical methodology.

Morphological characteristics, such as cellular monotony, nuclear palisading, and pseudorosette formation, can be used for diagnosis. If these characteristics are microscopically observed in breast cancer, immunohistochemical staining of neuroendocrine markers should be performed to differentiate invasive cancers from neuroendocrine carcinoma.

CgA and Syn have been recognized as diagnostic markers of NEBC; however, immunohistochemical methods have shown that sensitivity varies in both markers (CgA and Syn) in different cases [ 10]. Moreover, some researchers used monoclonal NSE antibody to detect an NSE protein, which is one of the diagnostic markers; nevertheless, the mRNA of NSE can also be detected in non-neurogenic cells and tumors [ 11]. In the present study, the immunohistochemically stained post-operative specimen of the patient showed that >50% of the cancer cells expressed the three proteins (NSE, CgA, and Syn). This finding supported the diagnosis of neuroendocrine carcinoma. Therefore, we proposed that the three markers (NSE, CgA, and Syn) should be used in combination to provide accurate diagnosis. Moreover, immunohistochemical staining results indicated that ER and CK7 were positively expressed, suggesting that NEBC may originate from the breast. NEBC is possibly induced by the neuroendocrine hormones produced heterogeneously by breast cancer cells because no cells similar to gastrointestinal neuroendocrine cells are found in normal breast tissue [ 12, 13].

NEBC is rare, and randomized control trials have not yet been performed; as such, no standard treatment protocol has been developed. Nevertheless, various chemotherapy protocols have been used to treat this disease. Systemic therapy proposals from small retrospective studies and neo-adjuvant therapy have not been elucidated. Sanguinetti et al. reported that a solid NEBC can be treated using neo-adjuvant chemotherapy with VP16+ cisplatin; the treatment showed that the tumor could be a stable disease [14]. In the present study, the 43-year-old patient was diagnosed with solid cohesive neuroendocrine carcinoma and received four cycles of TEC chemotherapy. The patient remarkably responded to chemotherapy with partial response based on RECIST criteria and Ki-67 staining significantly decreased from 40% to 10%. Thus, TEC protocol is a possible appropriate treatment for NEBC. We also proposed the use of regime containing anthracycline and taxanes. However, we cannot provide any conclusive recommendation because only one case with a short follow-up period was reported in this study.

In summary, primary NEBC is a very rare tumor. The diagnosis of NEBC depends mostly on its histological characteristics and positive immunohistochemical staining for neuroendocrine markers because specific clinical or imaging characteristics are usually absent. A standard chemotherapy for invasive NEBC could be used for adjuvant/neo-adjuvant chemotherapy.

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