Fukada Reona, Murakami Ayumi, Wada Tomoko, Inari Hitoshi, Yoshida Tatsuya
Breast Oncology, Saiseikai Yokohamashi Nanbu Hospital, Yokohama, Japan.
Pathology, Saiseikai Yokohamashi Nanbu Hospital, Yokohama, Japan.
Case Rep Oncol. 2025 Mar 26;18(1):531-538. doi: 10.1159/000545496. eCollection 2025 Jan-Dec.
Malignant peripheral nerve sheath tumors (MPNSTs) are common in the peripheral nerves of the head, neck, and limbs, with few reports of their occurrence in the breasts, and the epithelioid type is rare. Here, we aimed to report a case of an epithelioid MPNST of the breast.
A 76-year-old woman presented with bilateral breast masses. Pathological findings showed a 60-mm invasive ductal carcinoma (T3N0M0 stage IIB) on the right breast and an epithelioid MPNST on the left breast. After surgical resection, the patient was treated with endocrine therapy alone for right breast cancer, and no recurrence was observed 4 years after surgery.
Reports of MPNSTs in the breasts are rare. The pathological analysis showed atypia of spindle cells, positive staining for vimentin, S100, SOX10, and epithelial-like cells, and positive staining for cytokeratin AE1/AE3. H3K27me3 is reportedly absent in typical MPNSTs; however, it is expressed in epithelioid types. It sometimes occurs in patients with a germline mutation in , where INI1 is absent in tumor cells. In this case, the tumor cells expressed H3K27me3 and also maintained INI1.
恶性外周神经鞘瘤（MPNSTs）常见于头、颈和四肢的周围神经，发生于乳腺的报道较少，上皮样型罕见。在此，我们旨在报告一例乳腺上皮样MPNST病例。
一名76岁女性出现双侧乳腺肿块。病理结果显示右乳为60毫米浸润性导管癌（T3N0M0 IIB期），左乳为上皮样MPNST。手术切除后，患者仅接受了右乳癌内分泌治疗，术后4年未观察到复发。
乳腺MPNSTs的报道罕见。病理分析显示梭形细胞异型性，波形蛋白、S100、SOX10和上皮样细胞染色阳性，细胞角蛋白AE1/AE3染色阳性。据报道，典型MPNSTs中不存在H3K27me3；然而，它在上皮样型中表达。它有时发生在存在种系突变的患者中，肿瘤细胞中不存在INI1。在本病例中，肿瘤细胞表达H3K27me3且保留INI1。
