Fibromatosis-like metaplastic carcinoma of the breast: Two case reports

Abstract

Background: Fibromatosis-like metaplastic carcinoma is classified as a rare type of metaplastic carcinoma of the breast by the 2012 WHO pathological and genetic classification criteria for breast tumors, which takes hyperplastic spindle cells as the main component and is often misdiagnosed as benign stromal proliferative lesions or benign mesenchymal tumors of the breast because of its mild morphology. Here, we collected the clinical data of 2 cases of fibromatosis-like metaplastic carcinoma of the breast and performed pathomorphological observation and immunohistochemical staining of the surgically resected specimens. According to the clinical features, imaging features, immunophenotype, diagnosis and differential diagnosis of 2 cases of fibromatosis-like metaplastic carcinoma of the breast, it was further differentiated.

Case summary: Case 1: A 56-year-old postmenopausal female was admitted due to "right breast mass for over 1 year and local ulceration for over 1 mo". Physical examination showed a mass with a diameter of 4.5 cm × 5.5 cm palpable at 2.5 cm from the nipple at 1 o'clock in the right breast. The skin on the surface of the mass ruptured about 3 cm, with a small amount of exudation and bleeding, less clear boundary, hard texture, fair activity, without obvious tenderness. No obvious abnormality was palpable in the left breast. No enlarged lymph nodes were palpable in the bilateral axillae and bilateral supraclavicular region. After removing the mass tissue, it was promptly sent to the pathology department for examination. Case 2: Female, 52-years-old, premenopausal, admitted due to "right breast mass for more than 3 mo". Physical examination showed a 4.0 cm × 4.0 cm diameter mass palpable at 2.0 cm of the nipple in the lower outer 7 o'clock direction of the right breast, with less clear boundary, hard texture, fair activity, no significant tenderness, no palpable significant abnormalities in the left breast, and no palpable enlarged lymph nodes in the bilateral axillae and bilateral supraclavicular region. The mass was resected and sent for pathological examination. Postoperative pathological examination revealed fibromatosis-like metaplastic carcinoma of the breast in both patient 1 and patient 2. No systemic therapy and local radiotherapy were performed after surgery, and no tumor recurrence or metastasis was observed.

Conclusion: Fibromatosis-like metaplastic carcinoma of the breast is a rare subtype of metaplastic carcinoma that is often misdiagnosed, and the diagnosis relies on medical history collection, complete sampling, and full use of immunohistochemical assessment. The risk of lymph node and distant metastasis is low, and the current treatment is based on complete surgical resection. The efficacy of systemic radiotherapy and chemotherapy is not clear.

Keywords: Breast cancer; Fibromatosis-like metaplastic carcinoma; Metaplastic carcinoma; Pathology; Spindle cell lesion.

Figure 1

Right breast mass image of Case 1. A: A mass measuring 4.5 cm × 5.5 cm in diameter was palpable in the right breast 2.5 cm from the nipple at 1 o'clock; B: Postoperative specimen of right breast mass.

Figure 2

Puncture pathology and immunohistochemistry of right breast mass. A: HE staining showed that the tumor was composed of spindle cells with mild morphology and mild atypia of the tumor cells; B: Tumor cells were positive for CKPan by Envision assay; C: Envision test showed that tumor cells were positive for p63; D: Envision test showed tumor cells positive for CK5/6; E: Envision test showed approximately 15% Ki-67 for tumor cells. F: HE stained tumor was composed of spindle cells with mild morphology and mild atypia of tumor cells; G: Tumor cells were positive for CKPan by Envision assay; H: Tumor cells were positive for p63 by Envision assay; I: Tumor cells were partially positive for CK5/6 by Envision assay; J: Ki-67 hotspot area of tumor cells detected by Envision method was about + 25%. Original magnification: × 400; Scale bars: 100 μm.

Figure 3

Imaging data of right breast mass. A: Ultrasonography showed breast imaging reporting and data system (BI-RADS) grade V; B and C: magnetic resonance imaging (MRI) showed breast BI-RADS grade V. D: Ultrasound showed breast BI-RADS grade V; E: MRI showed breast BI-RADS grade V; F: Molybdenum target examination showed breast cancer BI-RADS grade IVb.

Figure 4

Postoperative pathology and immunohistochemistry of right breast cancer. A: HE staining showed that the tumor was composed of spindle cells with mild morphology and mild atypia of the tumor cells; B: Envision test showed tumor cells positive for CKPan; C: Envision test showed tumor cells positive for p63; D: Envision test showed tumor cells positive for CK5/6; E: Envision test showed approximately 20% Ki-67 for tumor cells. F: HE staining showed that the tumor was composed of spindle cells with mild morphology, and the tumor cells were mildly atypical; G: Tumor cells were positive for CKPan by Envision assay; H: Tumor cells were positive for p63 by Envision assay; I: Tumor cells were positive for CK5/6 by Envision assay; J: Ki-67 in tumor cells detected by Envision assay was about 20%. Original magnification: × 400; Scale bars: 100 μm.