Palisading Adenocarcinoma of the Sublingual Gland: Report of Two Rare Cases.

Palisading adenocarcinoma is a recently recognized, biphasic salivary gland tumor with a distinctive histomorphological pattern. Its low rate of local recurrence and absence of documented metastatic potential make accurate recognition clinically relevant. We report two cases of palisading adenocarcinoma arising in the sublingual gland of female patients aged 39 and 54 years. Both tumors were well-circumscribed and encapsulated, and showed solid growth composed of trabecular and islet-like structures with prominent peripheral palisading, admixed with ductal elements, with focal necrosis observed in one case. Immunohistochemically, the solid component demonstrated diffuse CD56 positivity, while chromogranin, synaptophysin, and INSM1 were negative. The ductal component showed strong CK7 expression with basal staining for p63, p40, and calponin. Although palisading adenocarcinoma lacks a characteristic diagnostic genetic alteration, its distinctive biphasic architecture, characteristic immunophenotype, and favorable clinical behavior warrant recognition as a distinct entity.