假肌源性血管内皮瘤(PMHE),一种罕见的血管肿瘤,于1992年首次被描述为纤维瘤样上皮样肉瘤,十年后,由于其与上皮样肉瘤和弥漫性细胞角蛋白表达的显着组织学重叠,将其称为上皮样肉瘤样血管内皮瘤。PHME目前被定义为一个独特的,潜在的中度恶性,很少有血管/内皮分化的转移性肿瘤。它的特点是年龄年轻(通常小于40岁),四肢位置(约80%),和t(7:19)SERPINE1::FOSB融合是最常见的分子改变。在这里,我们报道了一例59岁男性多灶性病变,包括右颞肌,右额顶颅骨,右侧翼状肌,右下颌髁突.右侧颞部病变的组织学检查显示,多结节双相病变由细长纺锤体和上皮样细胞浸润到相邻骨骼肌的片和束组成。注意到混合的大量嗜中性粒细胞浸润;然而,坏死区域,有丝分裂增加,核非典型性,或横纹肌母细胞样细胞缺失。免疫组化(IHC)染色显示肿瘤细胞弥漫性和FOSB强阳性,泛细胞角蛋白(AE1/AE3),CD31和ERG。分子测试表明t(9:19)EGFL7::FOSB融合mRNA。这个形态星座,IHC和分子检查结果与PMHE的诊断一致。这是第一例报道的多灶性PMHE与EGFL7::FOSB融合在50岁以上的患者的头颈部区域。由于PMHE的鉴别诊断包括具有侵袭性临床行为的高级别恶性肿瘤,再加上头颈部罕见的PMHE报告,对头颈部肿瘤的认识将避免对该实体的误诊和过度治疗。
Pseudomyogenic hemangioendothelioma (PMHE), a rare vascular neoplasm, was first described in 1992 asa fibroma-like variant of epithelioid sarcoma, and would be termed as epithelioid sarcoma-like hemangioendothelioma a decade later due to its significant histologic overlap with epithelioid sarcoma and diffuse cytokeratin expression. PHME is currently defined as a distinct, potentially intermediate malignant, rarely metastasizing neoplasm with vascular/endothelial differentiation. It is characterized by young age (typically less than 40 years old), extremity location (approximately ~80%), and t(7:19) SERPINE1::FOSB fusion as the most common molecular alteration. Herein, we report a case of a 59-year-old male presenting with multifocal lesions, including in the right temporalis muscle, right frontoparietal calvarium, right pterygoid muscles, and right mandibular condyle. Histologic examination of the right temporal lesion revealed a multinodular biphasic lesion composed of sheets and fascicles of elongated spindle and epithelioid cells infiltrating into the adjacent skeletal muscle. Admixed abundant neutrophilic infiltration is noted; however, areas of necrosis, increased mitosis, nuclear atypia, or rhabdomyoblast-like cells are absent. Immunohistochemical (IHC) staining showed that the tumor cells were diffusely and strongly positive for FOSB, pan-cytokeratin (AE1/AE3), CD31, and ERG. Molecular testing demonstrated a t(9:19) EGFL7::FOSB fusion mRNA. This constellation of morphological, IHC and molecular findings was consistent with a diagnosis of PMHE. This is the first reported case of multifocal PMHE with EGFL7::FOSB fusion in the head and neck area of a patient aged more than 50 years old. Since the differential diagnoses for PMHE includes high-grade malignancies with aggressive clinical behavior, coupled with the rare reports of PMHE in the head and neck region, awareness of this tumor in the head and neck region will avoid the misdiagnosis and overtreatment of this entity.