Zawawi M S F, Wan Ismail W F N, Mustapar N, Mohamad N, Nasir A, Tuan Sharif S E
Universiti Sains Malaysia, School of Medical Sciences, Department of Pathology, Health Campus, Malaysia.
Universiti Sains Malaysia, School of Medical Sciences, Department of Orthopaedics, Health Campus, Malaysia.
Malays J Pathol. 2022 Apr;44(1):115-120.
Malignant peripheral nerve sheath tumour (MPNST) is an uncommon malignant neoplasm of childhood with unfavourable prognosis. Only a limited number of cases have been reported in children less than 12 years of age, and approximately one-half arise from a benign peripheral nerve sheath tumour, especially in the background of neurofibromatosis type 1 (NF1). Primary MPNST in children is even rarer.
A 3-year-old Malay girl presented with painful right axillary swelling for six months, initially treated as axillary lymphadenitis and she defaulted follow up. She came back four months later with enlargement of the swelling. The previous biopsy was reported as Schwannoma, which correlates with a benign peripheral nerve sheath tumour's MRI findings. The final diagnosis after debulking surgery was consistent with MPNST. She succumbed to death 20 months after her initial diagnosis of advanced MPNST and lung metastasis.
Grossly, a huge partly circumscribed soft tissue mass was noted arising from a nerve with a solid greyish yellowish myxoid cut surface. Spindle-shaped cells arranged in a herringbone pattern alternated with areas of myxoid hypocellular areas exhibited marked pleomorphism, brisk mitosis, and extensive necrosis are seen microscopically. Immunohistochemistry shows patchy S100 protein staining with loss of expression of H3K27me3.
Although MPNST is rare in the paediatric age group, the diagnosis should be considered in children without NF1 with a rapidly evolving and painful mass in the peripheral nerve distribution. In this case, the diagnosis was delayed and made after surgery. Due to its morphologic heterogeneity and lack of specific immunohistochemical markers, MPNST remains a diagnostic challenge.
恶性外周神经鞘瘤（MPNST）是一种儿童期罕见的恶性肿瘤，预后不良。12岁以下儿童中仅报道了有限数量的病例，约一半起源于良性外周神经鞘瘤，尤其是在1型神经纤维瘤病（NF1）背景下。儿童原发性MPNST更为罕见。
一名3岁马来女孩因右腋窝疼痛性肿胀6个月就诊，最初被当作腋窝淋巴结炎治疗，随后失访。4个月后她因肿胀增大再次前来。之前的活检报告为施万细胞瘤，这与良性外周神经鞘瘤的MRI表现相符。肿瘤减容手术后的最终诊断为MPNST。她在初诊为晚期MPNST并伴有肺转移20个月后死亡。
大体上，可见一个巨大的、部分边界清楚的软组织肿块起源于一条神经，切面为实性灰黄色黏液样。显微镜下可见梭形细胞呈人字形排列，与黏液样细胞稀少区域交替出现，表现出明显的多形性、活跃的有丝分裂和广泛坏死。免疫组化显示S100蛋白呈局灶性染色，H3K27me3表达缺失。
尽管MPNST在儿童年龄组中罕见，但对于无NF1的儿童，若在外周神经分布区域出现迅速发展且疼痛的肿块，应考虑该病的诊断。在本病例中，诊断被延迟且在手术后才做出。由于其形态学异质性以及缺乏特异性免疫组化标志物，MPNST仍然是一个诊断难题。
