Involvement of the gastrointestinal tract by LCH is exceedingly rare, and few cases have been reported.
Langerhans cell histiocytosis (LCH) is a group of idiopathic disorders characterized by an abnormal proliferation of dendritic mononuclear cells that mostly involves the skin and bones. Recognizing amyloidosis in a differential diagnosis is important, as early recognition of this disorder could prevent further complications for the patient, shorten time to diagnosis, and explore management options in an efficient manner. To our knowledge, this was the first ever reported case of gastric amyloidosis at University Hospital (Columbia, Missouri). The patient's κ:λ ratio and serum electrophoresis were unremarkable, proving primary amyloidosis. This patient had no previous medical history of chronic inflammation, hematologic malignancy, renal disease, or family history, and the absence of risk factors suggested primary amyloidosis. Additional organ involvement was not found with imaging. These amyloid fibrils had a nonbranching, antiparallel twisted, β-pleated sheet configuration. Biopsies of stomach and colon showed waxy, pale eosinophilic extracellular aggregates on microscopy ( Figure 1.5, A), suggestive of amyloidosis, confirmed by Congo red staining ( Figure 1.5, B) with apple-green birefringence in polarized light ( Figure 1.5, C). He underwent esophagogastroduodenoscopy and colonoscopy. A 62-year-old man with past medical history of diverticulitis and colon resection presented to his physician with blood per rectum, unintentional weight loss, nausea, and vomiting for 1 month. The overall incidence of primary amyloidosis is 9 new cases per million persons, and involvement of gastrointestinal tract is exceptionally rare, with only an incidence of less than 1 per million. Common sites include kidney, heart, and liver, but gastrointestinal amyloidosis is rare. Clinical manifestations depend on the biochemical composition and site of deposition. Amyloidosis defines a group of disorders characterized by extracellular misfolded protein deposition, such as AL, AA, ATTR, and Aβ2M proteins.