Abnormalities of the salivary gland ducts leading to excessive accumulation or retention of ductal secretions, which can excite chronic inflammations. Immune, especially autoimmune, cause - which has gained steam, given the observation that the tissue of the glands is overrun with lymphoid immune cells  and fibrous connective tissue, as well as corroboration from markedly similar lesions (with histologic and immunohistochemical findings) seen elsewhere in the body. The presence of abundant Immunoglobulin G4 (IgG4) associated with Plasma cells infiltrating into the salivary glands, as well as increased serum IgG4 concentration, has been noted with patients with Küttners tumor.This chronic condition is primarily observed in adult (40–70 years) patients. However, Küttners tumor, with prominent immunopathological features, has been described in an 11-year-old boy in Brazil in 2012. Diagnosis
Given the difficulties of a definitive pre-operative diagnosis, the clinical entity of Küttners tumor has so far remained significantly under-reported and under-recognized. In recent times, armed with a better understanding of the occurrences and observable features of this condition, surgeons are increasingly depending upon pre-operative ultrasonography along with Fine-needle aspiration cytological (FNAC) examinations to make an accurate presumptive diagnosis, and according to one estimate, about 44% of patients undergoing submandibular resection are found to have this condition. In the ultrasonogram, Küttners tumor is characterized by a diffuse, heterogeneous zone of echo-shadows. The FNAC finds cells greatly reduced in number (called paucicellularity) along with scattered tubular ducts against a backdrop of lymphoplasmacytic infiltration and fibrous depositions.
Chronic sclerosing sialadenitis is a chronic (long-lasting) inflammatory condition affecting the salivary gland. Relatively rare in occurrence, this condition is benign, but presents as hard, indurated and enlarged masses that are clinically indistinguishable from salivary gland neoplasms or tumors. It is now regarded as a manifestation of IgG4-related disease.Involvement of the submandibular glands is also known as Küttners tumor, named after Hermann Küttner (1870–1932), a German Oral and Maxillofacial Surgeon, who reported four cases of submandibular gland lesions for the first time in 1896. Presentation
The inflammatory lesions in Küttners tumor may occur on one side (unilateral) or both sides (bilateral), predominantly involving the submandibular gland, but is also known to occur in other major and minor salivary glands, including the parotid gland. Overall, salivary gland tumors are relatively rare, with approximately 2.5–3 cases per 100,000 people per year seen in the Western world; however, salivary gland malignancies account for 3–5% of all head and neck cancers. However, salivary tumors show a great deal of morphological diversity, as well as variations in the nature of the lesion (malignant vs. benign):  approximately 20% to 25% of parotid tumors, 35% to 40% of submandibular tumors, and more than 90% of sublingual gland tumors are malignant. This situation underscores the diagnostic challenges in respect of Küttners tumor; despite being benign, this condition mimics the clinical appearance of malignancy in the salivary gland.