Local dissemination of osteosarcoma observed after massage therapy: a case report.

BACKGROUND: Limited evidence is available regarding the dissemination of tumor tissues due to compression during massage therapy, a routine procedure in patients with various symptoms in Asian countries. CASE PRESENTATION: A 12-year-old male presented at a massage clinic with pain and swelling of his left knee, which worsened the same night. Consistent with conventional osteosarcoma, radiography revealed cortical bone destruction, osteoblastic changes, and periosteal reactions. Magnetic resonance imaging revealed a tumor in the distal femur, an extraskeletal mass, and an infiltrative lesion in the intramuscular and neurovascular areas surrounding the distal femur; this was considered as hemorrhage and dissemination of the tumor tissue. 18Fluorine-labelled fluorodeoxyglucose-positron emission tomography and computed tomography revealed multiple metastases in the spine, liver, and lung. Consistent with osteosarcoma, histopathological examination revealed tumor cell proliferation with extensive pleomorphism and mitoses. Despite undergoing chemotherapy, radiation therapy, and hip disarticulation, the patient died due to multiple metastases 13 months after the initial diagnosis. CONCLUSIONS: The present case suggests association of massage therapy with the local dissemination of tumor tissues, although influence of massage therapy on metastatic lesions remains unclear. Massage therapists should be aware of the possibility for dissemination of hidden malignancies due to the procedure.