A Metastatic Detour- multifocal Skeletal Muscle Involvement in Tongue Squamous Cell Carcinoma: A Case Report

Abstract

Background: Skeletal muscle metastasis from squamous cell carcinoma of the tongue is uncommon and may complicate post-treatment surveillance. This case report describes early multifocal skeletal muscle metastases despite satisfactory locoregional disease control. Presentation of Case: A 41-year-old man with a six-month history of a progressively enlarging left lateral tongue lesion was diagnosed with moderately differentiated squamous cell carcinoma. Imaging demonstrated involvement of intrinsic and extrinsic tongue musculature without distant metastatic disease. He underwent left hemiglossectomy with bilateral modified radical neck dissection. Histopathological examination showed tumour-free surgical margins, perineural invasion, absence of Lymphovascular invasion, and no metastatic involvement in 35 cervical lymph nodes. Adjuvant radiotherapy was delivered to a total dose of 60 Gy in 30 fractions. Three months after treatment, the patient developed painful swellings over the left thigh and right upper back. FDG PET-CT demonstrated multiple metabolically active intramuscular lesions involving several muscle groups, together with cervical nodal and pulmonary abnormalities. Cervical nodal biopsy was negative for malignancy, while bronchoalveolar lavage supported a fungal pulmonary process. Biopsy of a muscular lesion was suggestive of poorly differentiated squamous cell carcinoma, consistent with metastatic disease from the tongue. Conclusion: Multifocal skeletal muscle metastases may develop despite locoregional control. Histopathological confirmation remains important when atypical FDG-avid lesions are identified during surveillance.