Distant Metastasis of Tongue Squamous Cell Carcinoma Presenting as Multiple Subdermal and Intramuscular Cysts: A Case Report

The most common sites of distant metastasis (DM) in squamous cell carcinoma (SCC) of the tongue are the lung, bone, and liver; the early identification of metastasis to other sites is difficult. This case report discusses a 48-year-old male initially diagnosed with advanced-stage left tongue SCC, which was treated with wide excision, left radical neck dissection, and adjuvant concurrent chemoradiotherapy. Two months after completing adjuvant therapy, multiple painful nodules without local erythematous changes or warmth were found in the bilateral posterior neck and right medial thigh. Ultrasonography of these nodules revealed a cystic structure. Fine needle aspiration cytology revealed metastatic SCC. The disease progressed despite salvage chemotherapy, and the patient passed away 4 months after the formation of the nodules. Subdermal and intramuscular cysts as the initial presentation of DM have rarely been reported. The identification of unusual cysts, even those outside the head and neck, should raise concern.