Discussion

Diagnosis

Collagenous gastritis, atrophic type.

Discussion

Collagenous gastritis (CG) is a rare gastrointestinal disorder that may present at any age with abdominal pain, nausea, vomiting, diarrhea, or anemia. There is a documented bimodal distribution with peaks in childhood and early adolescence and then in adulthood. Children most often present with abdominal pain or iron deficiency anemia, have a nodular mucosa on EGD, and disease limited to the stomach. In contrast, adults present with watery diarrhea, erythematous or normal mucosal findings on EGD, and frequently have concomitant autoimmune or gastrointestinal diseases including lymphocytic gastritis, celiac sprue, or lymphocytic colitis.

The diagnosis of CG is dependent upon histologic findings. CG is characterized by the accumulation of subepithelial collagen, often at least 10µm in thickness, and the accumulation of lymphoplasmacytic cells throughout the lamina propria. Additional supporting features include damaged epithelial cells, scattered intraepithelial lymphocytes, eosinophils, and entrapped capillaries.

In 2015, Arnason et al. proposed CG has three morphologic variants including lymphocytic, eosinophilic, and atrophic. Very similar to lymphocytic gastritis, the lymphocytic subtype of CG was determined by the presence of at least 25 intraepithelial lymphocytes per high power field. Eosinophilic gastritis was dependent upon at least 30 eosinophils per high power field. The atrophic subtype is rare and is characterized by sloughing epithelial cells, oxyntic cell atrophy, and pyloric gland metaplasia. Other groups believe that subtyping CG is unnecessary, as collagenous colitis has many of these histopathologic changes, yet this disease is not subclassified. The diagnosis of CG is confirmed with the aforementioned features and a trichrome stain highlighting the subepithelial collagen. Other ancillary studies that may be included are H. pylori, CD3, CD5, CD20, gastrin, and cyclin D1. These help rule out differential diagnoses, including H. pylori-related gastritis, autoimmune gastritis, lymphocytic gastritis, and lymphoma.

Currently, the etiology of CG remains unknown. The most popular theory is that the etiology is similar to that of collagenous colitis, in which chronic inflammation, due to toxins, infections, or autoimmune diseases, leads to the deposition of collagen as the body tries to heal itself. Some literature goes so far as to suggest that CG and collagenous colitis are the same disease, but at different stages of severity. Due to the bimodal distribution of the disease, it is presumed that there is likely more than one etiology. Other groups have suggested that collagen deposition in CG may be a result of eosinophil degradation and cytokine release, similar to eosinophilic esophagitis.

Treatment options include steroids and immunosuppressants; however, there is often limited or no response to therapy. Other medications including omeprazole, ranitidine, and sucralfate may also be prescribed. The best responses are seen in patients with concomitant celiac disease who are placed on a gluten-free diet and in patients with collagenous colitis treated with steroids and anti-inflammatory agents.

References 

Leung, S.T., et al., Collagenous gastritis: histopathologic features and association with other gastrointestinal diseases. Am J Surg Pathol, 2009. 33(5): p. 788-98.

Arnason, T., et al., Collagenous gastritis: a morphologic and immunohistochemical study of 40 patients. Mod Pathol, 2015. 28(4): p. 533-44.

Mandaliya, R., et al., Collagenous Gastritis a Rare Disorder in Search of a Disease. Gastroenterology Res, 2013. 6(4): p. 139-144.

Lagorce-Pages, C., et al., Collagenous gastritis: a report of six cases. Am J Surg Pathol, 2001. 25(9): p. 1174-9.

Ma, C., et al., A Comparative Clinicopathologic Study of Collagenous Gastritis in Children and Adults: The Same Disorder With Associated Immune-mediated Diseases. Am J Surg Pathol, 2015. 39(6): p. 802-12.

Kamimura, K., et al., Collagenous gastritis: Review. World J Gastrointest Endosc, 2015. 7(3): p. 265-73.

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