Primary squamous cell carcinoma of the breast in association with Zuska’s disease

Primary squamous cell carcinoma of the breast: a case report

INTRODUCTION

Squamous cell carcinoma (SCC) of the breast is a rare variant of invasive breast cancer that has been classified as metaplastic carcinoma. When a tumor is composed of spindle cells, diagnosis is challenging.

CASE REPORT

A 42-year-old woman with a large mass in the right breast underwent modified radical mastectomy. A pathological examination revealed a tumor with central necrosis in it. The tumor had a sarcomatoid growth pattern and the cells were spindle-shaped with severe atypicality. Immunohistochemical staining showed that P63, P53, vimentin, and CKpan were positive, whereas estrogen receptor and C-erbB-2 were negative. Ki-67 proliferation index was as high as 90%. Therefore, a diagnosis of SCC of the right breast was made. The patient received eight cycles of postoperative chemotherapy with paclitaxel and carboplatin, followed by seven cycles of radiotherapy. During follow-up, the patient also had a left thyroid tumor, and postoperative pathology suggested microinvasive follicular carcinoma. Since breast surgery, the patient has remained disease-free for more than four years.

CONCLUSION

SCC of the breast with spindle cell and sarcomatoid features is rare. The diagnosis of such tumors requires exclusion of tumors with similar histological morphologies.

Zuska's breast disease: Breast imaging findings and histopathologic overview

Zuska's disease describes the clinical condition of recurrent central or periareolar nonpuerperal abscesses associated with lactiferous fistulas. Pathogenesis involves the occlusion of an abnormal duct through an epithelial desquamation process that causes ductal dilatation, stasis of secretions, and periductal inflammation. Patients with Zuska's disease may develop chronic draining sinuses near the areola from lactiferous ducts fistula; therefore, the underlying abnormal duct system must be located and excised for proper treatment. Zuska's disease is often misdiagnosed and mistreated and is associated with significant morbidity, including the recurrence of abscess and cutaneous fistula formation. This case series aimed to help clinicians investigate and manage this disorder. The clinical and imaging findings, histopathologic correlation, and treatment of Zuska's disease are discussed.

Metaplastic Breast Carcinoma: Update on Histopathology and Molecular Alterations

CONTEXT—

Metaplastic carcinoma is a rare, triple-negative carcinoma of the breast that exhibits transformation of part or all of its glandular carcinomatous component into a nonglandular, or metaplastic, component. The World Health Organization currently recognizes 5 variants of metaplastic carcinoma based on their histologic appearance.

OBJECTIVE—

To review the histologic classifications, differential diagnosis, prognosis, and recent laboratory studies of metaplastic breast carcinoma.

DATA SOURCES.—

We reviewed recently published studies that collectively examine metaplastic carcinomas, including results from our own research.

CONCLUSIONS.—

Metaplastic breast carcinoma has a broad spectrum of histologic patterns, often leading to a broad differential diagnosis. Diagnosis can typically be rendered by a combination of morphology and immunohistochemical staining for high-molecular-weight cytokeratins and p63. Recent studies elucidate new genes and pathways involved in the pathogenesis of metaplastic carcinoma, including the downregulation of CCN6 and WNT pathway gene mutations, and provide a novel MMTV-Cre;Ccn6^fl/fl knockout disease-relevant mouse model to test new therapies.

Understanding the histogenesis of a HRAS-PIK3R1 co-driven metastatic metaplastic breast carcinoma associated with squamous metaplasia of lactiferous ducts

Metaplastic breast carcinoma (MBC) represents a heterogeneous group of aggressive primary breast cancers that can show differentiation into carcinomatous and sarcomatous elements. Due to its rapid growth, this malignancy can replace precursor lesions, which remain unknown in most cases. Herein, we describe a MBC presenting as a deceptive post-biopsy hematoma. Histopathological and immunohistochemical evaluation of the primary tumor revealed a squamous cell carcinoma arising in a background of squamous metaplasia of lactiferous ducts (SMOLD). In the absence of ductal carcinoma in situ, we consider SMOLD as a nonobligatory precursor of MBC. The tumor showed 'dedifferentiation' into spindle, mucin-producing, osteoclast-like giant cell and fibromatosis-like carcinoma. Next-generation sequencing revealed the driver mutations HRAS^Q61R and PIK3R1^{c.1738_1745+2del} in addition to MYH11^S638L and amplification of ERCC5 and FGF14, which were potential contributors to tumor phenotype. Tumor dedifferentiation was probably facilitated by epithelial-to-mesenchymal transition (EMT) with aberrant expression of platelet and endothelial adhesion molecule-1, leading to early metastasis via hematogenous route rather than lymphatic. The co-occurrence of phosphoinositide 3-kinase and mitogen-activated protein kinase pathway abnormalities along with EMT could mediate divergent growth in breast cancer.