An ultra-late maxillofacial cavity following multimodal treatment for adult head and neck rhabdomyosarcoma: a case report with a 16-year follow-up.

OBJECTIVE

To report a rare case of a patient with adult rhabdomyosarcoma (RMS) in the craniofacial region who developed a very late-stage left maxillofacial cavity after 16 years of multimodal treatment, and to systematically investigate the potential causal relationship between this complication and previous radiotherapy.

METHODS

A detailed report is presented on the diagnosis and treatment process of a 46-year-old female patient. A comprehensive evaluation framework was employed to analyze causality, encompassing temporal correlation, spatial alignment with the original radiation field, exclusion of alternative etiologies, and biological plausibility.

RESULTS

Approximately 16 years after the initial radiotherapy, the patient developed soft tissue defects and cavity formation in the core area of the original high-dose irradiation field. Although tissue biopsy was not performed due to post-radiotherapy site bleeding and patient constitution risks, imaging studies showed a high degree of consistency between the lesion and the previous radiotherapy area, with no evident evidence of tumor recurrence or primary infection, consistent with the pathophysiological process of radiation-induced tissue necrosis.

CONCLUSION

Despite the exceedingly long latency period, based on the conclusive spatial correlation, reasonable exclusion of other etiologies, and well-established radiobiological mechanisms, there is a "highly probable" causal relationship between the maxillofacial cavity and previous radiotherapy. This case serves as a warning that for long-term surviving RMS patients, extremely late radiation injury represents a serious complication risk that cannot be ignored.