Cervical squamous cell carcinoma manifesting as a solitary metastasis to the skeletal muscle of the scapular region accompanied by invasion of the adjacent bone while on PD-1 inhibitor maintenance therapy: a case report.

Cervical cancer is a common malignancy in women worldwide, with distant metastases frequently occurring in the lungs, liver, bones, and lymph nodes. However, this case report presents an extremely rare isolated metastasis to the left scapular region,specifically located between the supraspinatus and the trapezius muscles, in a patient with locally advanced cervical squamous cell carcinoma who developed this lesion during maintenance therapy with a programmed death receptor-1 (PD-1) inhibitor after completing concurrent chemoradiotherapy. The clinical presentation of this metastatic lesion was atypical and posed a significant diagnostic challenge; however, multimodal imaging (MRI, PET/CT) and histopathological examination ultimately confirmed the diagnosis of cervical cancer metastasis. This finding underscores the necessity of maintaining a high level of vigilance for metastases in atypical sites, even in the era of immunotherapy. To manage this rare presentation, a multidisciplinary team developed a comprehensive treatment strategy centered on surgical resection, followed by postoperative adjuvant radiotherapy administered concurrently with chemotherapy and anti-angiogenic therapy(Q3W) consisting of paclitaxel 135 mg/m², cisplatin 50 mg/m², and bevacizumab 10 mg/kg. The patient remained recurrence-free at 13 months, suggesting that a multimodal combined local and systemic strategy may be feasible for selected patients with solitary muscle metastasis. This case not only adds to the clinical understanding of rare metastases in cervical cancer but also demonstrates that tumors can still metastasize to atypical sites under immunotherapy. These findings highlight the need for vigilance regarding metastases at atypical sites during immunotherapy. Any underlying mechanism-including immune editing and clonal evolution-remains speculative in the absence of paired molecular data and requires further validation.