A Case of Advanced Basal Cell Carcinoma of the Head and Neck: Diagnostic Challenges and Sequential Systemic Therapy

Abstract

Advanced cutaneous malignancies with basaloid morphology can present diagnostic and therapeutic challenges, particularly when pathological interpretations differ and disease progresses during systemic treatment. We describe the clinical course of a 53-year-old woman with an extensive, unresectable cutaneous tumor involving the posterior neck and occipital region, accompanied by bilateral cervical lymphadenopathy and additional clinically suspected cutaneous deposits. The initial diagnosis was trichoblastic carcinoma, whereas expert pathological review favored basal cell carcinoma. The extent of disease precluded surgery and definitive radiotherapy. First-line vismodegib was initiated, and palliative radiotherapy delivering 30 Gy in 10 fractions to the occipital lesions and bilateral cervical lymph nodes was completed one year later. Clinical progression was documented three months after completion of radiotherapy; one month after this, MRI demonstrated extensive infiltration involving the left parotid gland and adjacent pharyngeal spaces. Second-line cisplatin and 5-fluorouracil were subsequently administered. Follow-up MRI six months after the earlier MRI demonstrated substantial tumor volume reduction. PET/CT three months later showed a heterogeneous response compared with a year earlier, including regression at several previously involved sites and newly apparent metabolically active right axillary lymph nodes. A subsequent biopsy was reported as basaloid carcinoma. The patient later experienced clinical deterioration, received one cycle of cemiplimab, and died before further treatment or response assessment. This case illustrates the importance of pathological clarification, longitudinal imaging, and careful interpretation of treatment response during sequential systemic therapy for advanced basal cell carcinoma.