Abstract
BackgroundFibromatosis-like metaplastic carcinoma (FLMCa), classified as a metaplastic carcinoma of the breast, is a very rare type of metaplastic carcinoma. We report a case of FLMCa that was difficult to diagnose.Case presentationThe patient was a 56-year-old postmenopausal woman who presented with a left-sided breast mass. A 1.3-cm irregular mass was found in the lower outer quadrant of the left breast on breast ultrasonography. She underwent core needle biopsy and vacuum-assisted biopsy, but the pathological findings only revealed inflammatory cell infiltration and a high level of fibrosis, with no malignant findings. At 3 months follow-up, she underwent a repeat breast ultrasonography, which revealed an increase in the size of the mass to 1.8 cm, and a repeat core needle biopsy, which showed a few spindle cells and squamous cells positive for cytokeratin (CK)5/6 and AE1/AE3, leading to the suspicion of FLMCa. Since the amount of tissue was insufficient to establish a definitive diagnosis, she underwent a lumpectomy. We found low-grade and slightly atypical spindle cells and partly atypical spindle cell carcinoma and squamous cell carcinoma. CK5/6 and α-SMA were positive, thus confirming FLMCa. Because the margins on the edge of the nipple side and anterior side were “ink on tumor”, she underwent a mastectomy and sentinel lymph node biopsy. After the surgery, she received adjuvant chemotherapy. At 3 years and 8 months of follow-up, no recurrent or metastatic lesions were identified in her body.ConclusionsFLMCa should be considered in the differential diagnosis when collagenous fibers are proliferating and malignancy is clinically suspected. Immunohistochemical analysis may be helpful in confirming this diagnosis.
Highlights
Fibromatosis-like metaplastic carcinoma (FLMCa), classified as a metaplastic carcinoma of the breast, is a very rare type of metaplastic carcinoma
FLMCa should be considered in the differential diagnosis when collagenous fibers are proliferating and malignancy is clinically suspected
We report a case of FLMCa that was difficult to diagnose based on tissue biopsy
Summary
Gobbi et al selected 241 cases of metaplastic features in breast tumors and investigated 30 cases in which lowgrade spindle cells accounted for more than 95% of the total area of the tumor and less than 5% were epithelial cells or low-grade carcinoma [1]. Sneige et al investigated 24 cases with the same definition, but found local recurrence in 2 cases and lung metastasis in 2 cases [3] They used the terminology “low-grade (fibromatosis-like) spindle cell carcinoma”. The reports by Gobbi et al and Sneige In this case, we were initially unable to diagnose the patient with FLMCa because the first and second biopsies revealed few tumor cells that were slightly atypical and were negative for AE1/AE3. We were initially unable to diagnose the patient with FLMCa because the first and second biopsies revealed few tumor cells that were slightly atypical and were negative for AE1/AE3 This caused us to followup on her.
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