A case of multiple synchronously diagnosed brain metastases from alveolar soft part sarcoma without concurrent lung involvement

BACKGROUND: Alveolar soft part sarcoma (ASPS) is a rare soft-tissue sarcoma with a propensity for early hematogenous dissemination to the lungs and frequent brain metastasis. The development of lung metastasis almost invariably precedes intracranial involvement. There are no previously reported cases in which a patient was synchronously diagnosed with ASPS and multiple brain metastasis without lung involvement. CASE DESCRIPTION: A 29-year-old gentleman was found to have three intracranial lesions following the onset of generalized seizures. Staging studies identified a soft-tissue mass in the left thigh and an adjacent femoral lesion. Biopsy of the soft-tissue mass was consistent with ASPS. The patient then underwent neoadjuvant stereotactic radiotherapy to all three brain lesions, followed by en bloc resection of the dominant lesion. The patient was then started on a programmed death-ligand 1 (PD-L1) inhibitor. Subsequent surgical resection of the primary lesion and femur metastasis demonstrates a histopathologic complete response of the bony metastasis and partial response of the primary lesion. At present, the patient has received 14 cycles of atezolizumab without recurrence of the primary or bony lesions and the irradiated intracranial disease has remained stable without recurrence of the resected dominant lesion. CONCLUSION: While intracranial involvement is relatively common in ASPS, a case with multiple, synchronously diagnosed brain metastasis without concurrent lung metastasis has not been described. The presented case discusses the safety and efficacy of aggressive management of intracranial disease in the setting of atezolizumab. Prospective evaluation of the efficacy of checkpoint inhibitors and the prognostic value of PD-L1 expression in ASPS with brain metastasis are necessary.