Adenosquamous Carcinoma with the Acantholytic Feature in the Oral Cavity: A Case Report and Comprehensive Literature Review.

Adenosquamous carcinoma (ASC) is an aggressive subtype of squamous cell carcinoma (SCC). Due to its poor prognosis, a precise pathological diagnosis of ASC is essential but challenging because its pathological criteria are still unclear. Here, we present a rare case of oral ASC accompanied by acantholytic features. The tumor was raised in the mandibular gingiva and recurred locally approximately 13 months after the initial surgery with cervical lymph node metastasis. Pathological specimens of the primary lesion showed acantholysis in a large area of the SCC. Mucous cells, the characteristic finding indicating glandular differentiation, were imperceptible in the initial surgical specimen but increased in the locally recurrent and metastatic lymph node specimens. In a comprehensive literature review of oral ASC cases, the present case was the only case of ASC with acantholytic features. We reconfirmed that ASC has poor prognoses, such as low 5-year overall survival and disease-free survival, high locoregional recurrence, and high distant metastasis rates. A precise diagnosis of ASC is required for estimating prognosis and undergoing close follow-up, even if the adenocarcinomatous component is limited to a small area in the lesion.