Localized Thoracic Swelling in a School-Aged Child: Suspected Trauma or Something More Serious? A Case Report.

Introduction: Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue neoplasm, typically located at the deep tissues of the trunk and extremities, that occurs mostly in the young adult age. Very few cases of children affected are reported in the literature, that interestingly tend to present with superficially sited tumors. Though benign in appearance, LGFMS can potentially behave as a malignant tumor with local recurrence or even distal metastases. Case description: We report a case of a six-year-old boy with a rare presentation of an asymptomatic superficial thoracic mass, that raised our suspicion due to its progressively enlarging size and when surgically excised it proved to be a LGFMS. Conclusion: This case raises awareness for atypical presentations of LGFMS in children with superficial growing lesions, which can be misdiagnosed and therefore maltreated. Complete excision and long-term surveillance are the main treatment components for the patients' safety, since the potential of malignancy cannot be ruled out in this type of tumor.