Diagnostically Challenging Subtypes of Invasive Lobular Carcinomas: How to Avoid Potential Diagnostic Pitfalls
Nektarios Koufopoulos,
Ioannis S. Pateras,
Alina Roxana Gouloumis,
Argyro Ioanna Ieronimaki,
Andriani Zacharatou,
Aris Spathis,
Danai Leventakou,
Panagiota Economopoulou,
Amanda Psyrri,
Nikolaos Arkadopoulos,
Ioannis G. Panayiotides
Affiliations
Nektarios Koufopoulos
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Ioannis S. Pateras
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Alina Roxana Gouloumis
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Argyro Ioanna Ieronimaki
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Andriani Zacharatou
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Aris Spathis
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Danai Leventakou
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Panagiota Economopoulou
Medical Oncology Unit, 2nd Department of Internal Medicine-Propaedeutic, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Amanda Psyrri
Medical Oncology Unit, 2nd Department of Internal Medicine-Propaedeutic, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Nikolaos Arkadopoulos
4th Department of Surgery, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Ioannis G. Panayiotides
Second Department of Pathology, Medical School, Attikon University Hospital, National and Kapodistrian University of Athens, Chaidari, 12462 Athens, Greece
Invasive lobular carcinoma is the most common special breast carcinoma subtype, with unique morphological (discohesive cells, single-cell files, targetoid pattern) and immunohistochemical (loss of E-cadherin and β-catenin staining) features. Moreover, ILC displays a poor response to neoadjuvant therapy, a different metastatic pattern compared to invasive breast carcinoma of no special type, as well as unique molecular characteristics. In addition to the classic variant of invasive lobular carcinoma, several other well-recognized variants exist, including classic, alveolar, tubulolobular, solid, pleomorphic, signet-ring, and mixed. Furthermore, three novel variants of invasive lobular carcinoma, i.e., with extracellular mucin production, papillary features, and tubular elements, have been described during the last decade. We herewith focus on the unique morphological and immunohistochemical characteristics of these novel varieties of invasive lobular carcinoma, as well as differential diagnostic considerations and potential diagnostic pitfalls, especially when dealing with biopsy specimens.
