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

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.

Bioinformatics analysis of human kallikrein 5 (KLK5) expression in metaplastic triple‐negative breast cancer

Background:Metaplastic breast carcinoma(MBC)is a rare breast cancer subtype;most cases are triple‐negative breast cancers(TNBCs)and are poorly responsive to conventional systemic therapy.Few potential diagnostic and prognostic markers for distinguishing between metaplastic TNBC and nonmetaplastic TNBC have been discovered.We performed bioinformatic analysis to explore the underlying mechanism by which metaplastic TNBC differs from nonmetaplastic TNBC and provides potential pathogenic genes of metaplastic TNBC.Methods:Differentially expressed genes(DEGs)in metaplastic tumors and nonmetaplastic tumors from TNBC patients were screened using GSE165407.The GSE76275 data set and The Cancer Genome Atlas(TCGA)database were used to screen DEGs in TNBC and non‐TNBC.Metascape and DAVID were used for the Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis and Gene Ontology(GO)analysis of DEGs.Online databases,including UALCAN,GEPIA,HPA,Breast Cancer Gene‐Expression Miner,and quantitative PCR and western blot,were used to examine KLK5 messenger RNA and protein expression in breast cancer.Analysis of KLK5‑associated genes was performed with TCGA data,and the LinkedOmics database was used to detect the genes co‐expressed with KLK5.STRING(Search Tool for the Retrieval of Interacting Genes)and Cytoscape were used to screen for hub genes.Kaplan‑Meier plotter was used for survival analysis.Results:KLK5 was identified among the DEGs in nonmetaplastic TNBC and metaplastic TNBC.The KLK5 gene was overexpressed in nonmetaplastic TNBC but downregulated in metaplastic TNBC.KEGG and GO analyses revealed that epithelial‐to‐mesenchymal transition was a pathogenic mechanism in metaplastic TNBC and an important pathway by which KLK5 and its associated genes DSG1and DSG3 influence metaplastic TNBC progression. Prognosis analysis showedthat only low expression of KLK5 in metaplastic TNBC had clinical significance.Conclusion: Our research indicated that KLK5 may be a pivotal moleculewith a key role in the mechanism of tumorigenesis in metaplastic TNBC.