Broad Fibrovascular Cores in Papillary Lesions of the Breast
Broad Fibrovascular Cores in Papillary Lesions of the Breast
Aims A prominent fibrovascular stromal core is one of the widely accepted histological features of breast papillomas, but some papillary carcinomas also show such broad fibrovascular cores, leading to confusion in diagnosis, particularly in needle biopsy specimens. We investigated the histological characteristics of papillary lesions, focusing on broad fibrovascular cores and their relationship with the architectural patterns.
Methods Among 185 cases of needle biopsies of papillomas and papillary carcinomas, the number of cases with broad fibrovascular cores in each group was compared. The broad fibrovascular core density in the subsequently resected specimens was evaluated and compared between papillary predominant pattern (papillary structures >80% of tumours) and mixed pattern (papillary, solid, cribriform and others) within the lesions.
Results Significantly more papillary carcinomas than papillomas and B3 atypical papillary lesions had broad fibrovascular cores (p=0.0091 and p=0.0164, respectively). The papillary predominant pattern was more prominent in carcinomas than in papillomas in the needle biopsies (p=0.048) and showed the same tendency in the resections (p=0.058). The broad fibrovascular core density was significantly lower in the 18 papillomas than in the 37 papillary carcinomas (p=0.0079) and was not significantly different between the papillary predominant and mixed patterns in carcinomas and papillomas.
Conclusions Broad fibrovascular cores in mammary papillary lesions are not specific for papillomas, as they are also present focally in papillary carcinomas. As the frequency of papillary carcinoma with broad fibrovascular cores is relatively high, caution in diagnosis has to be exercised, especially in needle biopsy specimens.
One of the most challenging diagnosis in assessing papillary lesions of the breast is distinguishing a papilloma from papillary carcinoma. Papillary lesions are characterised by finger-like projections or fronds composed of fibrovascular cores covered by epithelium. The papillary fronds of benign papillomas are covered by an inner myoepithelial cell layer and an outer epithelial layer. One of the important differentiations between papillomas and papillary carcinomas is that the stroma is 'prominent' with fibrosis and epithelial entrapment in papillomas but is 'delicate' in papillary carcinomas. Solid papillary carcinomas are also considered variants of papillary carcinomas as histologically circumscribed solid nodules. Discrete papillae are not apparent; the underlying papillary structure is represented by a network of blunt or broad fibrovascular cores among the solid cellular proliferation. These stromal fibrovascular cores are often embedded within the solid epithelial proliferation and are extensively hyalinized. In other papillary carcinomas, secondary changes of sclerosis may also result in broad fibrovascular cores. This may be one of the reasons for the difficulty in distinguishing between papillomas and papillary carcinomas, especially in needle biopsies. The usefulness of high-molecular weight cytokeratins (HMWCK) for distinguishing papillary carcinomas from papillomas was recently reported. However, the use of HMWCK in the 'papillary' area of papillary lesions is less dependable. Thus, in papillary lesions with mostly 'papillary' areas with superimposed proliferation of atypical epithelial cells with prominent stroma, it would be difficult to differentiate between a papilloma, papilloma with atypical ductal hyperplasia (ADH)/ductal carcinoma in situ (DCIS) and papillary DCIS, especially in needle biopsies (figure 1). Although needle biopsies are generally accurate for diagnosing papillary lesions, the management of non-malignant papillary lesions diagnosed at needle biopsies is still debated. Few studies have focused on the stroma in papillary lesions, and it is timely to review the findings in this area, particularly in cases with predominately papillary pattern and broad fibrovascular cores, where the diagnostic role of HMWCK was less dependable. Therefore, using adequate number of needle biopsy materials, we investigated the diagnostic issues related to papillary lesions with an emphasis on broad fibrovascular cores.
(Enlarge Image)
Figure 1.
Needle biopsy specimen of a papillary carcinoma. The fragment tissues show papillary predominant structures with or without sclerotic broad fibrovascular cores.
Abstract and Introduction
Abstract
Aims A prominent fibrovascular stromal core is one of the widely accepted histological features of breast papillomas, but some papillary carcinomas also show such broad fibrovascular cores, leading to confusion in diagnosis, particularly in needle biopsy specimens. We investigated the histological characteristics of papillary lesions, focusing on broad fibrovascular cores and their relationship with the architectural patterns.
Methods Among 185 cases of needle biopsies of papillomas and papillary carcinomas, the number of cases with broad fibrovascular cores in each group was compared. The broad fibrovascular core density in the subsequently resected specimens was evaluated and compared between papillary predominant pattern (papillary structures >80% of tumours) and mixed pattern (papillary, solid, cribriform and others) within the lesions.
Results Significantly more papillary carcinomas than papillomas and B3 atypical papillary lesions had broad fibrovascular cores (p=0.0091 and p=0.0164, respectively). The papillary predominant pattern was more prominent in carcinomas than in papillomas in the needle biopsies (p=0.048) and showed the same tendency in the resections (p=0.058). The broad fibrovascular core density was significantly lower in the 18 papillomas than in the 37 papillary carcinomas (p=0.0079) and was not significantly different between the papillary predominant and mixed patterns in carcinomas and papillomas.
Conclusions Broad fibrovascular cores in mammary papillary lesions are not specific for papillomas, as they are also present focally in papillary carcinomas. As the frequency of papillary carcinoma with broad fibrovascular cores is relatively high, caution in diagnosis has to be exercised, especially in needle biopsy specimens.
Introduction
One of the most challenging diagnosis in assessing papillary lesions of the breast is distinguishing a papilloma from papillary carcinoma. Papillary lesions are characterised by finger-like projections or fronds composed of fibrovascular cores covered by epithelium. The papillary fronds of benign papillomas are covered by an inner myoepithelial cell layer and an outer epithelial layer. One of the important differentiations between papillomas and papillary carcinomas is that the stroma is 'prominent' with fibrosis and epithelial entrapment in papillomas but is 'delicate' in papillary carcinomas. Solid papillary carcinomas are also considered variants of papillary carcinomas as histologically circumscribed solid nodules. Discrete papillae are not apparent; the underlying papillary structure is represented by a network of blunt or broad fibrovascular cores among the solid cellular proliferation. These stromal fibrovascular cores are often embedded within the solid epithelial proliferation and are extensively hyalinized. In other papillary carcinomas, secondary changes of sclerosis may also result in broad fibrovascular cores. This may be one of the reasons for the difficulty in distinguishing between papillomas and papillary carcinomas, especially in needle biopsies. The usefulness of high-molecular weight cytokeratins (HMWCK) for distinguishing papillary carcinomas from papillomas was recently reported. However, the use of HMWCK in the 'papillary' area of papillary lesions is less dependable. Thus, in papillary lesions with mostly 'papillary' areas with superimposed proliferation of atypical epithelial cells with prominent stroma, it would be difficult to differentiate between a papilloma, papilloma with atypical ductal hyperplasia (ADH)/ductal carcinoma in situ (DCIS) and papillary DCIS, especially in needle biopsies (figure 1). Although needle biopsies are generally accurate for diagnosing papillary lesions, the management of non-malignant papillary lesions diagnosed at needle biopsies is still debated. Few studies have focused on the stroma in papillary lesions, and it is timely to review the findings in this area, particularly in cases with predominately papillary pattern and broad fibrovascular cores, where the diagnostic role of HMWCK was less dependable. Therefore, using adequate number of needle biopsy materials, we investigated the diagnostic issues related to papillary lesions with an emphasis on broad fibrovascular cores.
(Enlarge Image)
Figure 1.
Needle biopsy specimen of a papillary carcinoma. The fragment tissues show papillary predominant structures with or without sclerotic broad fibrovascular cores.
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