1. ¹Department of Pathology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
2. ²Department of Pathology, Hospital General, Alicante, Spain
3. ³Department of Oncology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
4. ⁴Department of Radiology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain

Correspondence: Enrique Lerma, Department of Pathology, Hospital Santa Creu i Sant Pau, Avda. Sant Antonio Ma Claret, 167, Barcelona 08025, Spain. E-mail: elerma@santpau.es

Received 3 April 2007; Revised 10 August 2007; Accepted 10 August 2007; Published online 21 September 2007.

Abstract

Basal breast carcinomas triple negative for estrogen receptors, progesterone receptors and Her2/neu breast carcinomas are more aggressive than conventional neoplasms. We studied 64 cases with immunohistochemistry, using 23 antibodies, to characterize diverse pathological pathways. A basal cytokeratin was identified in 81% of tumors and vimentin was identified in 55%. The mean Ki67 index was 46% (range, 10–90%). Coincident expression of p50 and p65, which suggests an active nuclear factor-B factor, was present in 13% of neoplasms. Epithelial growth factor receptor (EGFR), insulin-like growth factor-I receptor (IGF-IR) or c-kit (CD117) was identified in 77% of tumors. Loss of protein tyrosine phosphatase was found in 14%, whereas Akt activation was present in 28%. Several differences were identified between two subtypes of basal breast carcinomas: the pure variant (negative S-100 and actin) was more frequently associated with 'in situ carcinoma' (P=0.019) and pBad overexpression (P=0.098), whereas the myoepithelial variant (positive S-100 or actin) showed more frequent tumor necrosis (P=0.048), vimentin expression (P=0.0001), CD117 expression (P=0.001) and activated caspase-3 (P=0.089). IGF-IR could be as important as EGFR for the growth of these neoplasms. Basal cell carcinoma has at least two subtypes with distinct microscopic and immunohistochemical features.