Synchronous oral squamous cell carcinomas with unusual histopathological feature.

Patients with head and neck carcinomas have high incidence (2-3% per year) of second primary lesions. Although "field cancerization" was first described in oral squamous cell carcinomas (OSCCs), only few studies have been concentrated on multifocal primary squamous cell carcinomas in the oral cavity. Synchronous carcinomas are defined as second neoplasms at the same time or within 6 months period of primary lesions. After this period, they are considered as metachronous neoplasms. Tumors composed exclusively or in large part of clear cells are rare in salivary glands, jaws and oral mucosa. OSCCs composed of clear cells or clear cell variant are not documented in the English literature. We present an unusual case of synchronous OSCCs composed predominantly of clear cells.