DISEASE CHARACTERISTICS: Histologically confirmed squamous cell carcinoma of the head and neck that is recurrent or refractory following at least 1 course of therapy Primary or metastatic tumors involving skin, nodes (palpable and biopsy- proven), subcutaneous tissue, or muscle allowed No involvement of major artery or any visceral organ Measurable lesions accessible for direct intratumoral injection with no immediate risk of hemorrhage or embolization Most troublesome tumor (identified by the investigator) at least 0.5 cc and no greater than 20 cc Smaller tumors eligible for treatment but not for efficacy assessment An improvable primary treatment goal (palliative or preventive) for most troublesome tumor must be identified by the investigator prior to enrollment If multiple tumors qualify as most troublesome and share the primary physician-selected treatment goal, the largest tumor is selected Patient may also select a most troublesome tumor and 1 palliative treatment goal for that tumor (need not match the physician-selected tumor or goal) No fibrotic lesions (e.g., previously irradiated lesion with no subsequent disease progression) No tumors involving or threatening to invade the carotid or other major vessel