Mantle cell lymphoma of the hard palate: a case report and review of the differential diagnosis based on the histomorphology and immunophenotyping pattern.

To our knowledge, mantle cell lymphoma (MCL) has never been reported in the hard palate, but it is commonly observed in the nasopharynx and Waldeyer's tonsillar ring. MCL is characterized by a diffuse infiltrate of small lymphocytes with the expression of CD5, CD20, and cyclin D1 (Bcl-1), but not CD10. MCL presenting in the hard palate must be accurately distinguished from other forms of so-called small B-cell lymphomas-such as small lymphocytic lymphoma, follicular lymphoma, and extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue-because MCL possesses a worse prognosis. Awareness of MCL of the hard palate will prompt pathologists to perform adequate immunohistochemical analysis to aid in confirming the diagnosis.