Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barley. Classic symptoms include gastrointestinal problems such as chronic diarrhoea, abdominal distention, malabsorption, loss of appetite, and among children failure to grow normally. This often begins between six months and two years of age. Non-classic symptoms are more common, especially in people older than two years. There may be mild or absent gastrointestinal symptoms, a wide number of symptoms involving any part of the body, or no obvious symptoms. Coeliac disease was first described in childhood; however, it may develop at any age. It is associated with other autoimmune diseases, such as Type 1 diabetes mellitus and Hashimotos thyroiditis, among others.Coeliac disease is caused by a reaction to gluten, a group of various proteins found in wheat and in other grains such as barley and rye. Moderate quantities of oats, free of contamination with other gluten-containing grains, are usually tolerated. The occurrence of problems may depend on the variety of oat. It occurs in people who are genetically predisposed. Upon exposure to gluten, an abnormal immune response may lead to the production of several different autoantibodies that can affect a number of different organs. In the small bowel, this causes an inflammatory reaction and may produce shortening of the villi lining the small intestine (villous atrophy).
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.