Plasma cell gingivitis (PCG), an infrequent benign inflammatory condition of unknown etiology, is a type of plasma cell orificial mucositis, which includes a wide spectrum of conditions. We present the case of a 13-year-old girl who had PCG with an erythematous congestive plaque on the anterior maxillary gingiva for 4 years. Occasionally, the lesion became increasingly swollen and painful and bled. Results of a histopathologic examination showed dense plasmacytic infiltrate in the dermis, affecting the dermoepidermal border, with immunohistochemical positivity in the K and A light chains and vascular proliferation. "Lozenge" keratinocytes, "watery" spongiosis, and exocytosis were seen in the epidermis. Laboratory analysis showed notably low levels of both serum IgA and secretory IgA. We consider whether secretory IgA at low levels has an important etiopathogenic role favoring the development of localized subclinical repetitive infections that could lead to chronic PCG.