Inaishi Takahiro, Sakuma Takahiko, Fukuoka Tomoki, Ichihara Shu
Department of Breast and Endocrine Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, Japan.
Department of Diagnostic Pathology, Toyohashi Medical Centre, 50 Hamamichi-Gami, Imure, Toyohashi, Aichi, Japan.
Int J Surg Case Rep. 2022 Jul;96:107382. doi: 10.1016/j.ijscr.2022.107382. Epub 2022 Jul 2.
Mammary myofibroblastoma (MFB) is a rare tumour. Its clinical and pathologic characteristics have been only sporadically described. A case of epithelioid variant of MFB is reported with the diagnostic tips, the differential diagnoses, and a discussion on the possible pathogenesis.
A 74 year-old woman presented with a painless nodule in the left breast. Core needle biopsy (CNB) revealed a tumour primarily composed of epithelioid cells. Despite epithelioid appearance of the tumour cells, ductal/lobular components were absent within the tumour. As cell lineage of the epithelioid cells could not be determined with CNB, lumpectomy was performed to obtain definitive diagnosis and, at the same time, to remove the lesion. Histologically, the tumour consisted of multiple epithelioid cell nests that were spread over fibrous stroma infiltrated with adipose tissue. Spindle cells were also present, but they were fewer than epithelioid cell clusters. Occasionally, the tumour cells showed nuclear atypia. It was difficult to determine whether this tumour was benign or malignant solely with Hematoxylin-eosin stain. However, with the aid of immunohistochemical analyses, we could make a histodiagnosis of epithelioid subtype of myofibroblastoma.
The differential diagnoses of epithelioid MFB include ductal, lobular, metaplastic carcinomas and mesenchymal tumours. Comprehensive knowledge of classic and variant MFB is necessary for the correct diagnosis.
Pathologic diagnosis of epithelioid variant of MFB requires careful evaluation of histology and the use of a panel of immunohistochemistry. Female phenotype of breast stroma may play a role in the pathogenesis of MFB.
乳腺肌纤维母细胞瘤（MFB）是一种罕见肿瘤。其临床和病理特征仅有零星报道。本文报告1例MFB上皮样变型病例，并给出诊断要点、鉴别诊断及对可能发病机制的讨论。
一名74岁女性，左乳出现无痛性结节。粗针活检（CNB）显示肿瘤主要由上皮样细胞组成。尽管肿瘤细胞呈上皮样外观，但肿瘤内无导管/小叶成分。由于CNB无法确定上皮样细胞的细胞谱系，遂行肿块切除术以明确诊断并同时切除病变。组织学检查显示，肿瘤由多个上皮样细胞巢组成，散布于浸润脂肪组织的纤维性间质中。也存在梭形细胞，但比上皮样细胞簇少。肿瘤细胞偶尔显示核异型性。仅通过苏木精-伊红染色很难确定该肿瘤是良性还是恶性。然而，借助免疫组化分析，我们得以做出肌纤维母细胞瘤上皮样亚型的组织学诊断。
上皮样MFB的鉴别诊断包括导管癌、小叶癌、化生性癌和间叶性肿瘤。正确诊断需要全面了解经典型和变型MFB。
MFB上皮样变型的病理诊断需要仔细评估组织学并使用一组免疫组化方法。乳腺间质的女性表型可能在MFB的发病机制中起作用。
