Pathological findings of rare pediatric soft tissue tumors

Abstract

Soft tissue tumors are rare and distinct entities, accounting for only 15.4% of pediatric solid tumors. Accurate pathological diagnoses must align with clinical treatment strategies, and tumors for which established treatment regimens or targeted therapies based on specific genetic mutations are available must be identified. Although highly sensitive diagnostic markers have been reported for certain tumors, such as rhabdomyosarcoma, Ewing sarcoma, and malignant rhabdoid tumor, preparing the necessary immunohistochemical antibodies is often extremely difficult in general hospitals. Furthermore, confirming gene translocation is important; however, few facilities are equipped to perform such analyses.

Disease classification based on genetic alterations may expand in the field of pediatric soft-tissue tumors. For example, NTRK-rearranged spindle cell neoplasms exhibit gene fusions, such as ETV6::NTRK3 and LMNA::NTRK1 (an intrachromosomal rearrangement). However, as NTRK fusions have been identified across various tumor types, including soft tissue, brain, and breast cancers, genetic abnormalities should be interpreted in conjunction with histological morphology.

Although the importance of accurate diagnosis in pediatric soft tissue tumor treatment is evident, clinicians and pathologists must understand the diagnostic capabilities available within their respective institutions. In difficult or ambiguous cases, proactive consideration should be provided to submitting samples for comprehensive genomic panel testing.