Left inguinal dedifferentiated liposarcoma and primary unclassified sarcoma of the left lung as synchronous multiple sarcomas: a case report.

Background: Pulmonary nodules in patients with soft tissue sarcomas are likely pulmonary metastases, whereas synchronous primary pulmonary sarcomas are rare. Without surgery, determining whether a solitary pulmonary nodule is a primary or metastatic nodule is difficult. Herein, we report a rare case of a primary pulmonary sarcoma that presented synchronously with a primary dedifferentiated liposarcoma.

Case presentation: A 77-year-old man presented to another hospital with left inguinal swelling and a suspected recurrent inguinal hernia. Computed tomography revealed a left inguinal mass and pure-solid nodule in the left lung and the patient was referred to our hospital for detailed examination and treatment. The inguinal mass was pathologically diagnosed as a dedifferentiated liposarcoma using needle biopsy, whereas bronchoscopic biopsy revealed histological findings suggestive of a sarcoma; however, the primary site could not be determined. Positron emission tomography-computed tomography revealed no high-accumulation lesions except for the two sarcomas. We decided to perform surgery on both sarcomas for diagnostic and curative purposes. The surgical specimens showed that the two sarcomas were different. Based on the immunohistochemical staining findings of MDM2, a left inguinal dedifferentiated liposarcoma and primary pulmonary unclassified sarcoma were diagnosed. The patient displayed no evidence of recurrence 1 year after surgery.

Conclusions: We encountered a rare case of synchronous multiple primary sarcomas, one presenting in the lung and the other in the soft tissue. Surgery was required to achieve a definitive diagnosis for the patient, who achieved disease-free survival at 1 year. This case suggests that proactive resection of pulmonary nodules in patients with soft tissue sarcomas may be feasible as a diagnostic treatment if complete resection is achieved.