Table 1A: Case series.

HeadingS: NA = Not available data; Clin Pres = Clinical presentation; US = breast Ultrasound; MX = mammography; Bio = biopsy; Cit = citology; Ad treat = adjuvant treatment (chemotherapy and/or hormone therapy); Adj RT = adjuvant radiotherapy; Tum size = tumor size (centimeters); LNs = lymph nodes removed; CrA = Chromogranin A; Syn = Synaptophisin; ER = Estrogen receptor; PR = Progesterone receptor; Her2 = her2-neu receptor; FUP = follow-up (months).

Clinical and radiological findings: Pos = positive for malignancy; Neg = negative for malignancy; BM = Breast Mass; CM = carcinomatous mastitis; N+ = axillary adenopathy, PBM = Painful breast mass; BL = breast lump; SR = Skin retraction, NR = nipple retraction, PLM = Paget-like Mass; BND = Bloody nipple discharge; UBM = Ulcerated Breast Mass; MBM = Multilobulated breast mass; HyBM = Hypoechoic (US) / Hypodense (MX) breast mass; Hyp = Hyperechoic (US) / Hyperdense breast mass = HeBM = Heterogeneous breast mass, SBM = Spiculated breast mass, Mic = microcalcifications, BoMet = Bone Metastases; LMet = Lung metastasis; PAMet = Perianal metastases, PiMet = Pituitary metastases; PaMet = Pancreatic metastases; PE = Pleural effusion; MMet = Multiple metastases; IBM = Isoechoic breast mass
Neg = Negative; Sus = suspicious; LMet = lung metastasis.
Mast = Mastectomy; BCS = Breast Conservative Surgery; SLNB = Sentinel Lymph Node Biopsy; ALND = Axillary Lymph Node Dissection.

Chemotherapy: ChT = chemotherapy (not defined); HoT = hormone therapy (not defined); CDDP = Cisplatin, CBL = Carboplatin, VP-16 = Etoposide, CPT-11 = Irinotecan, 5-FU = Fluorouracil, EPI = Epirubicin, CAP = Capecitabine, DTX = Docetaxel, 5’-DFUR = 50 deoxy-5-fluorouridine, Tor = Toremifene, CPA = Cyclophosphamide, EPI = Epirubicin, Tam = Tamoxifen, Tor = Torenifene, Let = Letrozole, S = Streptozotocin, MTX = Methotrexate, Ana = Anastrazole, AI = Aromatase inhibitor, LHRH = Leutinising hormone releasing hormone analogue, UFT = Uracil & Tegafur, PTX = Paclitaxel, ADR = Adriamycin (Doxorubicin), Sando = Sandostatin, Som = Somatostatin; Ever = Everolimus, Bev = Bevacizumab, Erl = Erlotinib; Palb = Palbociclib; Oct = Octreotide.

Histology: SCNC = Small Cell Neuroendocrine Carcinoma, ICNE = Invasive carcinoma with neuroendocrine differentiation; NET = well-differentiated neuroendocrine tumor; NEC = poorly differentiated neuroendocrine carcinoma.

Follow-up: NED = No evidence of disease; AWD = Alive with disease; DOD = Died of disease; DUC = Died of Uncertain cause †Median follow-up.