Complaint of a progressively growing nodule in the left breast, for approximately 10 months.
She denied skin changes, nipple discharge, or any other local symptoms.
There was no additional concerns.
Images (A and B) from the physical examination revealed a palpable, hardened tumor located in the left breast (white circles). Additionally, there was slight redness of the overlying skin (white arrow) (C). The tumor is partially adhered to deep planes, measuring approximately 10,0 × 8,0 cm, and presents as a significant and well-defined entity on physical palpation. The other systems assessed during the physical examination were within normal limits.
Imaging Findings
Mammograms of the left breast, in the craniocaudal (A) and mediolateral (B) views, show an irregular, indistinct hyperdense nodule (white arrows) located in the inferomedial quadrant. Mammogram with cleavage view (C) shows the previously described nodule associated with skin thickening of the left breast.
Ultrasound images (D and E) of the left breast show a nodule with peripheral flow on color and spectral Doppler study (circle). Ultrasound image (F) shows an irregular, indistinct nodule producing a strong posterior acoustic shadow (white arrowhead), located in the junctions of the medial quadrants, of the left breast
Differential Diagnoses
Breast Abscess
Fibroadenoma
Invasive Lobular Carcinom (ILC)
Inflammatory Breast Cancer
Invasive Ductal Carcinoma (IDC)
Metaplastic Carcinoma
Histological sections prepared with hematoxylin-eosin showing breast tissue with small fragments of cartilaginous and neoplastic bone tissue (black outlines and black circle), with optical microscopy (O.M.) at 10X magnification (A and B) and an O.M. at 40× magnification (C, D, and E).
Histological section (F) with CK-7 immunohistochemical preparation showing the differentiation of breast tissue into bone tissue (black arrow), with an O.M. of 10× magnification.
Histological section (G) with Ki-67 immunohistochemical staining, with an O.M. of 40× magnification, classified as having low Ki-67 expression (black arrow).
Metaplastic Breast Carcinoma Demonstrating Heterologous Differentiation into Osseous and Cartilaginous Tissues
Narriman Patú Hazime | Santa Casa de Misericórdia de São Paulo
Additional imaging studies were requested for better disease staging:
Axial (A) and sagittal (B) images of a computed tomography (CT) scan, with contrast agent, show a large solid expansive formation, irregularly contoured and partially calcified (white arrows), located in the left breast.
Coronal CT video (C) and image (D) with contrast agent showing a nodule with diffuse, predominantly peripheral calcification (white arrowheads).
Magnetic Resonance Imaging (MRI) Findings
Axial (A) T2-weighted FSE image showing a nodule with a low signal relative to fibroglandular tissues in the left breast. Axial (B) and Sagittal (C) 3D MIP reconstruction postcontrast image showing a nodule with rapid initial heterogeneous enhancement, and adjacent hypervascularization in the left breast. Axial (D, E, F, G) T1 images showing a nodule with early enhancement, and washout in the late phases in the left breast à ACR BI-RADS® 6.
After the histopathological diagnosis was obtained through core biopsy, and disease staging through imaging examinations, the patient underwent neoadjuvant chemotherapy.
Four cycles of doxorubicin and cyclophosphamide were administered, followed by four cycles of taxane-based chemotherapy.
Image (A) of the physical examination of the patient after completing neoadjuvant chemotherapy reveals a persistent palpable nodule in the left breast.
Mammograms of the left breast, in the craniocaudal (A) and mediolateral (B) views, showing an irregular, indistinct hyperdense nodule (white arrows) located in the medial lower quadrant. After systemic treatment, there was a slight reduction in the total volume of the nodule à ACR BI-RADS® 6.
Surgical Treatment
A medial sectorectomy was performed.
The excised tissue was sent for intraoperative freezing, and free margins were visible upon analysis.
Lymph nodes stained with patent blue were sampled, none of which showed signs of compromise.
A dermomuscular flap was constructed and positioned centrally in the left breast.
Macroscopic examination of the surgical specimen revealed a nodular lesion covered by skin with surgical sutures along its lateral aspect, measuring approximately 9,0 × 7,0 cm.
Macroscopic cross-section of the surgical specimen (B) revealed a heterogeneous nodular lesion, as demonstrated by imaging studies, with apparent tumoral necrosis.
Patient Follow Up
During the postoperative period, the patient developed pulmonary thromboembolism.
Ultimately, she passed away due to its complications.
Definitive Anatomopathological Diagnosis:Metaplastic Carcinoma Demonstrating Heterologous Differentiation into Osseous and Cartilaginous Tissues.
Histological section (A) prepared with hematoxylin-eosin showing distinctive features of heterologous differentiation, characterized by the presence of areas showing osseous and cartilaginous differentiation within the tumor mass (black outline), with an O.M. of 20×.
Histological section (B) prepared with hematoxylin-eosin showing that osteoclastic-like giant cells are within the osseous component of the tumor (black outline), further indicating its metaplastic nature and osteogenic differentiation, with an O.M. of 20×.
Histological section (C) prepared with hematoxylin-eosin showing cartilaginous differentiation within the tumor mass (black outline), with an O.M. of 10×.
Rad-Path Correlation
The correlation between imaging methods (A, B, C, D, E) and anatomopathological samples (F and G) shows outstanding representativeness of the lesion in the diagnostic methods employed.
Metaplastic Breast Carcinoma
Metaplastic breast carcinoma (MBC) is a rare variant of triple-negative breast cancer (TNBC), that accounts for less than 1% of all invasive breast cancers.
There are limited data and consensus, but it appears as a fast-growing mass in women over 50 years of age, with no breast side preference. It metastasizes via the bloodstream and rarely involves lymph nodes, commonly affecting the lungs and bones.
MBC is more aggressive, has greater metastatic potential and local recurrence rates, and a poorer prognosis.
Most MBC cases are triple-negative, leading to resistance to chemotherapy, hormonal therapy, and targeted therapies, making management challenging.
Imaging Findings Of MBC With Heterologous Mesenchymal DifferentiationMammography:
Margins: May appear circumscribed, obscured, or indistinct (yes).
Density: Typically high (yes).
Calcifications: Less common but may be present, especially in matrix-producing subtypes.
Ultrasound:
Echo Structure: Often shows a complex structure with cystic components due to necrosis, although it can also be solid.
Margins: May be circumscribed, microlobulated, or indistinct (yes).
Posterior Features: Can demonstrate posterior acoustic shadowing (yes).
Case Images
Mammogram (A) in the mediolateral view, showing an irregular, indistinct hyperdense nodule.
Ultrasound (B) revealed an irregular, indistinct nodule producing a strong posterior acoustic shadow.
MRI:
Signal Intensity:
– T2-weighted images: Isointense or hypointense signal compared to fat and normal fibroglandular tissue (yes), associated with interspersed heterogeneous high signal (yes), often indicating necrotic components.
Enhancement Patterns:
– Ring-like enhancement is common, with nonenhancing solid portions often at the periphery (yes).
A) Axial T2-weighted FSE image showing a nodule with a low signal relative to fat and fibroglandular tissues and interspersed heterogeneous high signal intensity.
(B) Sagittal 3D MIP reconstruction postcontrast image showing a nodule with heterogeneous enhancement.
Importance of Imaging Exams:
Narrowing the differential diagnosis.
Guided interventions (biopsy and surgical).
Follow-up monitoring of treatment progress.
A definitive diagnosis requires histopathological evaluation, including immunohistochemistry analysis.
The mammogram (A) reveals an irregular, indistinct, hyperdense nodule. These findings correlate with those of the surgical specimen (B), and its histological section (C), which were prepared with hematoxylin-eosin stain, which revealed that the breast tissue contained small fragments of cartilaginous and neoplastic bone tissue at a magnification of 10×.
REFERENCES
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