Spontaneous regression of intraoral spindle cell carcinoma with subsequent regional nodal metastasis – A unique case report with review of literature

Spindle cell squamous cell carcinoma (SpSCC) is an uncommon, aggressive biphasic variant of oral SCC, known for high recurrence and poor prognosis. Spontaneous regression (SR) of malignant tumours is an exceptionally rare phenomenon, particularly in intraoral carcinomas. We report a unique case of SpSCC in a 66-year-old male, where 1 month post incisional biopsy, the primary intraoral lesion showed complete spontaneous regression, though regional submandibular lymph node metastasis subsequently developed. Diagnosis was established through histopathology and immunohistochemistry, with positivity for cytokeratin, p63, and vimentin. A literature review revealed very few documented instances of SR in oral malignancies, often following diagnostic procedures, potentially due to biopsy-induced immune activation and alterations in the tumour microenvironment. This case underscores the enigmatic nature of SR in oral cancers and highlights the need for long-term surveillance, while raising important considerations about immune mechanisms and their potential therapeutic implications in head and neck oncology.