Identification of clinical factors related to antibody-mediated immune response to the subfornical organ.

OBJECTIVE: We recently reported cases of adipsic hypernatremia caused by autoantibodies against the subfornical organ in patients with hypothalamic-pituitary lesions. This study aimed to clarify the clinical features of newly identified patients with adipsic hypernatremia whose sera displayed immunoreactivity to the mouse subfornical organ. DESIGN: Observational cohort study of patients diagnosed with adipsic hypernatremia in Japan, United States, and Europe. METHODS: The study included 22 patients with adipsic hypernatremia but without overt structural changes in the hypothalamic-pituitary region and congenital disease. Antibody response to the mouse subfornical organ was determined using immunohistochemistry. The clinical characteristics were compared between the patients with positive and negative antibody responses. RESULTS: Antibody response to the mouse subfornical organ was detected in the sera of 16 patients (72.7%, female/male ratio, 1:1, 12 pediatric and 4 adult patients). The prolactin levels at the time of diagnosis were significantly higher in patients with positive subfornical organ (SFO) immunoreactivity than in those with negative SFO immunoreactivity (58.9 ± 33.5 vs. 22.9 ± 13.9 ng/ml, p < .05). Hypothalamic disorders were found in 37.5% of the patients with positive SFO immunoreactivity. Moreover, six patients were diagnosed with rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation/neural tumor syndrome after the diagnosis of adipsic hypernatremia. Plasma renin activity levels were significantly higher in patients with serum immunoreactivity to the Nax channel. CONCLUSIONS: The patients with serum immunoreactivity to the SFO had higher prolactin levels and hypothalamic disorders compared to those without the immunoreactivity. The clinical characteristics of patients with serum immunoreactivity to the subfornical organ included higher prolactin levels and hypothalamic disorders, which were frequently associated with central hypothyroidism and the presence of retroperitoneal tumors.

[A case of liver metastasis 11 years after resection of a gastrointestinal stromal tumor of the duodenum].

A 77-year-old Japanese man with a gastrointestinal stromal tumor (GIST) had undergone a duodenectomy 11 years prior. At that time, he had an incidentally detected left renal cell carcinoma, for which he underwent a nephrectomy and was followed-up at our institution. Twenty-four months after the nephrectomy, a 13-mm low-density mass was found on abdominal computed tomography (CT). Contrast-enhanced ultrasonography indicated an irregular hyperenhancement in the vascular phase and a defect on the post-vascular image. A tumor biopsy for differential diagnosis revealed that the tumor was a GIST. Since positron emission tomography-CT and capsule endoscopy revealed no evidence of a primary lesion, we performed a partial hepatectomy without adjuvant treatment. Microscopic examination revealed that the tumor consisted of uniform spindle cells with a fascicular growth pattern. Immunohistochemical examination revealed c-kit and CD34 expressions, similar to those found in the resected duodenal GIST specimen 11 years prior. We diagnosed metastatic liver tumor from the duodenal GIST resected 11 years prior. The patient remains alive without disease recurrence 24 months after the hepatectomy. Long-term surveillance is required after resection of a high-risk primary GIST.