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Case Report Volume 17 Issue 3
Heterogeneity of extensive invasive lobular carcinoma. part II: combination of the classic extralobular diffuse subtype with intralobular colonies of invasive lobular carcinoma
László Tabár, Peter B Dean, Miklós Tarján, Wendy Yi- Ying Wu, Hsiu-Hsi Chen, Amy Ming- Fang Yen
Department of Mammography, Falun Central Hospital, Sweden
Department of Diagnostic Radiology, Faculty of Medicine, University of Turku, Finland
Department of Clinical Pathology and Cytology, Falun Central Hospital, Sweden
Department of Radiation Sciences, Oncology, Umeå University, Sweden
National Taiwan University, Taipei, Taiwan
School of Oral Hygiene, College of Oral Medicine, Taipei Medical University, Taiwan
Received: April 23, 2026 | Published: May 18, 2026
Citation: Tabár L, Dean PB, Tarján M, et al. Heterogeneity of extensive invasive lobular carcinoma. part II: combination of the classic extralobular diffuse subtype with intralobular colonies of invasive lobular carcinoma. J Cancer Prev Curr Res. 2026;17(3):66‒70. DOI: 10.15406/jcpcr.2026.17.00609
Abstract
Background: The classic, diffuse invasive lobular carcinoma (ILC) consists of malignant cells arranged in single files spreading throughout much of the extralobular breast mesenchyme and separated by layers of newly formed fibrous connective tissue. An unappreciated variant of ILC consists of a similar microscopic appearance but with the malignant cells mostly restricted to the intralobular mesenchyme, surrounding the terminal ducts and acini, which have histopathologically normal breast lobular epithelia. These intralobular ILC foci form colonies reaching sizes of one or more centimetres. We report here an extensive (75x43 mm) tumour diagnosed as ILC and consisting predominantly of these malignant intralobular colonies, and compare the long-term follow-up of 312 consecutive intralobular and extralobular cases sized ≥20 mm. Case presentation: A 72-year-old woman presented with a self-detected extensive thickening in the retroareolar and central portion of her right breast, associated with nipple-areola retraction. Three consecutive mammographic examinations are presented; the first at age 69, 30 months before diagnosis (normal), the second 23 months later, and the third seven months later, at age 72, when she presented with clinical symptoms. The histopathologic diagnosis was a 75x43 mm-sized ILC tumour consisting of many colonies with the above-described concentric arrangement of malignant cells situated within the intralobular mesenchyme. There have been no signs of recurrence at her annual follow-up examinations, the most recent being eleven years and two months after her mastectomy. Results: The 15-year survival of the intralobular cases was 92 % versus a significantly poorer 69% survival of the extralobular cases. Conclusions: There are two distinct subtypes of classic ILC, one of which is the extensive, classic, diffusely invasive lobular carcinoma and another, which is the hitherto unappreciated ILC variant, where the malignancy is mostly confined to the intralobular mesenchyme of the terminal ductal lobular units (TDLUs). The overall extent of these intralobular colonies is commonly restricted to 1-19 mm. The malignant cells within each affected TDLU surround the terminal ducts and acini containing normal luminal epithelial cells. These two breast malignancy subtypes have vastly different long-term outcomes and divergent clinical, imaging, histopathologic, and long-term outcome characteristics. This case report describes an extensive malignancy in which the classic, extralobular, diffuse subtype combines with colonies of invasive lobular carcinoma, and has a predominance of the intralobular subtype.
Keywords: Breast cancer, invasive lobular carcinoma, imaging biomarkers, breast cancer of mesenchymal origin
©2026 Tabár, et al. This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and build upon your work non-commercially.