Upper Gastrointestinal Langerhans Cell Histiocytosis: A Report of 2 Adult Cases and a Literature Review.

Langerhans cell histiocytosis (LCH) with primary involvement of the upper gastrointestinal (GI) tract is rare. We report 2 adult cases of localized LCH in the upper-GI tract, including the second reported adult case of esophageal LCH and review 11 previously reported cases. Case 1 involved the esophagus of a 61-year-old man; histiocytosis was detected when endoscopy was performed for an examination of epigastric pain. Case 2 involved the stomach of a 56-year-old woman wherein the lesion was detected during a follow-up endoscopy after Helicobacter pylori infection. Both biopsy specimens exhibited diffuse proliferation of mononuclear cells with nuclear convolution and a background of eosinophilic infiltrate. The cells were immunohistochemically positive for CD1a and langerin, and BRAF V600E mutation was detected in Case 2. Follow-up endoscopy for both cases revealed that the lesions disappeared without any treatment. It is important to avoid misdiagnosing LCH of the upper-GI tract as a malignant neoplasm.

A ganglion-rich gastrointestinal stromal tumor: A case report.

We report a case of an extremely rare type of duodenal gastrointestinal stromal tumor (GIST) that included neuronal components. Although gastrointestinal autonomic nerve tumors (GANTs), a subtype of GISTs, exhibit ultrastructural features of the nerve plexus, neuronal cells have not been observed within GANTs or GISTs. GISTs originate from interstitial cells of Cajal (ICCs), which are markedly different from the progenitor cells of neural elements and neural-crest-derived stem cells. This may explain why GISTs typically lack neuronal elements. It remains unclear that the neuronal components of this tumor are neoplastic or hyperplastic, but proliferation and survival of ICCs have recently been reported to be closely related to neurons. Although we could not find the KIT, PDGFR, and BRAF mutation as far as we examined, it may have had a rare mutation in NF1, a fusion of EVT6-NTRK3, or an as-yet-unknown KIT mutation that affected neurogenesis. Further investigation of related genetic mutations and accumulation of data from other similar cases is needed.

Histopathological characterization of the neuroglial tissue in ovarian teratoma associated with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis.

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a rare but occasionally fatal limbic encephalitis that may be accompanied by ovarian teratoma. Since the neuroglial tissue within the teratoma may be involved in the pathogenesis of this encephalitis, we attempted morphological and immunohistochemical characterization of the neuroglial tissue in four cases of ovarian teratoma associated with anti-NMDA receptor encephalitis and 12 control cases, i.e., six consecutive cases of immature teratoma and six cases of mature teratoma with an abundant neuronal component, focusing mainly on NMDA receptor-expressing neurons. NMDA receptor-expressing neurons, being observed in all of the cases analyzed, were significantly densely aggregated (P = 0.030, Wilcoxon test) and relatively smaller in size in the encephalitis-associated cases than in the control cases, and the Ki-67 labeling index of neuroglial cells with these neurons was significantly higher in the encephalitis-associated cases (P = 0.004, Wilcoxon test). In the cases with encephalitis, aggregation of B-cells within or around the neuroglial tissue was also observed. Our present findings may be useful for more accurate diagnosis of anti-NMDA receptor encephalitis and contribute to a better understanding of the pathogenesis.

Hypoglycemia Unawareness in Insulinoma Revealed with Flash Glucose Monitoring Systems.

The delayed diagnosis of insulinoma remains a clinical issue. One of the main causes of such a delay is hypoglycemia unawareness. A 53-year-old woman fell unconscious during postprandial exercises. Flash glucose monitoring (FGM) systems revealed glucose profiles with fasting hypoglycemia, which facilitated the clinical diagnosis of insulinoma even though she was unaware of her hypoglycemia. The preoperative comparison of the blood glucose values provided by FGM with those obtained from capillary blood were consistent. Thus, FGM may have potential utility in revealing the presence of insulinoma-induced hypoglycemia.