Case Presentation: A 66-year-old female presented from the Dominican Republic with a 6-month-history of progressive weight loss, worsening confusion and inability to ambulate. On exam, she was alert and oriented to person only, pale but otherwise stable. Her neurological exam was pertinent for dysdiadokinesis and a positive Romberg sign. Her labs were notable for pancytopenia, including a macrocytic anemia, an elevated LDH and a decreased haptoglobin. The peripheral blood smear demonstrated hyperlobulated neutrophils. Further investigation for anemia revealed low levels of vitamin B12 in addition to a positive parietal cell antibody and intrinsic factor antibody test confirming the diagnosis of pernicious anemia. An EGD was performed and biopsies showed a marked loss of oxyntic glands, linear neuroendocrine hyperplasia, pseudopyloric and intestinal metaplasia as well as scattered lamina propria lymphoplasmacytic infiltrates. Such histomorphologic findings are consistent with autoimmune atrophic gastritis, a common cause and finding seen in pernicious anemia. Subsequently, gastrin levels were found to be markedly elevated at 2737 pg/mL. Given the association of atrophic gastritis with other autoimmune disorder, a thyroid workup was performed confirming an additional concurrent diagnosis of Hashimoto’s Thyroiditis.

Discussion: Vitamin B12 is a cofactor in erythropoiesis and myelin production. Over time a myelodysplastic-like syndrome and a subacute combined degeneration of the spinal cord result. The neurologic symptoms are due to myelin degeneration and loss of nerve fibers in the dorsal and lateral columns of the spinal cord and cerebral cortex which can present with symptoms of unsteady gait, weakness and change in mental status. Failure of erythropoiesis is manifested as pernicious anemia, in which autoimmune destruction of the gastric mucosa including parietal cells disrupt B12 absorption and over decades can progress to autoimmune gastric atrophy. This is a chronic inflammatory process whose hallmark finding is the transformation of oxyntic mucosa with ensuing gastric glandular cell atrophy and metaplasia. Antibodies to parietal cells are routinely seen.

Pernicious anemia is found globally and is frequently associated with other autoimmune processes. Thyroid disease occurs in 20% of patients with pernicious anemia and 53% of patients with atrophic gastritis, an association termed thyrogastric autoimmunity. The pathogenesis behind this association is an area of active research.

Conclusions: Autoimmune illnesses tend to cluster together. A thorough workup is required to avoid the sequelae of undiagnosed and untreated autoimmune diseases. This vignette highlights the importance of recognizing such associations as they are often reversible and treatable. Our patient presented with severe symptomatic vitamin B12 deficiency and was diagnosed with autoimmune atrophic gastritis in concurrence with Hashimoto’s thyroiditis illustrating a typical presentation of thyrogastric autoimmunity.