Isolated Langerhans cell histiocytosis in the hypothalamic-pituitary region: a case report

Potential indication of chemotherapy for hypodipsia and arginine vasopressin deficiency secondary to hypothalamic-pituitary Langerhans cell histiocytosis: a case report and literature review

Hypothalamic-pituitary Langerhans cell histiocytosis (HP-LCH) is often associated with arginine vasopressin deficiency (AVD). Patients with AVD caused by HP-LCH rarely develop an impaired osmotic threshold for thirst (OTT). Improvement in OTT among such patients has not been reported in the literature. To our knowledge, here we report the first case of AVD due to HP-LCH in which hypodipsia resolved during chemotherapy. A nine-year-old Japanese girl presented with polydipsia, polyuria, anorexia, and hypernatremia (149.8 mEq/L) and was diagnosed with AVD secondary to HP-LCH. Visual analog scale examination showed a reduced OTT following the water deprivation test. During chemotherapy for Langerhans cell histiocytosis (LCH), serum sodium concentrations became stable between 138.9 and 142.9 mEq/L under the replacement of desmopressin. Repeated visual analog scale examinations showed that she experienced a sense of thirst at a serum sodium concentration of 142.3-144.6 mEq/L, at which she did not experience any thirst prior to the initiation of chemotherapy. These data suggest that chemotherapy directly improved the OTT in our patient. Improved mechanical compression or infiltration of the hypothalamus related to OTT may lead to the recovery of the sense of thirst. This report highlights the potential role of chemotherapy for solitary HP-LCH in patients with hypodipsia and AVD.

Infantile-Onset Isolated Neurohypophyseal Langerhans Cell Histiocytosis with Central Diabetes Insipidus: A Case Report

Central diabetes insipidus (CDI) is a rare disease in children and has a variety of etiologies. The major causes of CDI with pituitary stalk thickening (PST) are germinoma, Langerhans cell histiocytosis (LCH), and Lymphocytic infundibulo-neurohypophysitis, which are difficult to differentiate by imaging and require pathological diagnosis. We report a case of infantile-onset isolated neurohypophyseal LCH diagnosed by pathological findings. A 2-year-old girl presented with polydipsia and polyuria. CDI was diagnosed and treatment with oral desmopressin was initiated. Magnetic resonance imaging (MRI) of the head showed PST and absence of high-signal intensity of posterior pituitary on T1-weighted images. Follow-up MRI scans showed that the tumor mass was gradually increasing and extending posteriorly toward the area near the mamillary body. Simultaneously, anterior pituitary dysfunction was observed. She underwent a biopsy of the PST and LCH was diagnosed by immunohistochemical analysis. DNA analysis showed no BRAF V600E mutation. Monotherapy with 2-Chlorodeoxyadenosine reduced the tumor size but did not improve pituitary function. Isolated neurohypophyseal LCH should be considered in infantile-onset cases of CDI with PST. 2-CdA treatment resulted in rapid PST shrinkage. Further cases are needed to determine whether early diagnosis and treatment can prevent anterior pituitary dysfunction.

Multifocal, Multisystem Presentation of Adult-Onset Langerhans Cell Histiocytosis on 18F-Fluorodeoxyglucose Positron-Emission Tomography-Computed Tomography: A Rare Case Report

Langerhans cell histiocytosis (LCH), also known as histiocytosis X, is a rare systemic disorder arising from clonal proliferation of immature CD207-positive (langerin) myeloid dendritic cells (histiocytes) in the skin and visceral organs with a tendency to involve single or multiple organ systems with variable clinical course and prognosis. The incidence of LCH is very less in adult and occurs almost exclusively in children. Genital, perianal, and lung lesions are considered to be rare manifestations of adult LCH. We describe a case of 31-year-old, nonsmoker female who presented in February 2020 with itching and burning sensation in perianal and vulvar regions accompanied with multiple nonhealing ulcers and papillomatous lesions. These lesions gradually increased in size with no response to antibiotics and topical steroids. She was advised positron-emission tomography- computed tomography (PET-CT) scan for further evaluation. After PET-CT scan, her provisional diagnosis of multisystem, multifocal Langerhans cell histiocytosis with high-risk organ involvement was made. Both vulvar and perianal lesions were biopsied which was suggestive of Letterer-Siwe variant of LCH. The prognosis of this variant is very poor even with aggressive chemotherapy and 5-year survival rate of only 50%. Hence, it requires careful consideration during diagnosis and management.