Lymph node metastasis in spindle cell carcinoma arising in odontogenic cyst. Report of a case. The majority of primary intraosseous carcinomas of the jaws develop in preexisting odontogenic cysts. These tumors are usually well-differentiated keratinizing carcinomas with relatively good prognosis. Only two of 41 previously reported acceptable cases of primary intraosseous carcinomas from ex-odontogenic cysts were associated with cervical lymph node metastasis. Spindle cell carcinoma is an anaplastic dimorphic neoplasm with poor prognosis. It has a special predilection for the upper aerodigestive tract. This is to our knowledge the first report of spindle cell carcinoma developing in an odontogenic cyst. Cervical lymph node metastasis showing typical histologic features of spindle cell carcinoma was detected 8 months postoperatively. The prognostic implications of this finding are discussed in light of previously reported cases of intraosseous carcinoma arising in odontogenic cysts and of spindle cell carcinoma of the oral cavity. 