Stromal melanocytosis of an adenoid cystic carcinoma arising from the palatal minor salivary gland

An unusual case of adenoid cystic carcinoma arising from the palatal minor salivary gland in a 63-year-old Japanese female is reported. In addition to the characteristic histopathologic features of adenoid cystic carcinoma, spindle- and dendritic-shaped cells containing excessive amounts of melanin pigment were densely and widely distributed in the stroma resulting in a blue nevus-like appearance. Neither melanocytes nor melanin pigments were seen within the parenchyma. The possible histogenesis of melanocytes in the stroma of the salivary gland carcinoma is discussed, although no firm conclusion could be drawn.