Introduction: Arginine vasopressin (AVP) deficiency is an uncommon but important presentation of infiltrative hypothalamic– pituitary disorders. In adults, isolated AVP deficiency with pituitary stalk thickening is diagnostically challenging, especially in the absence of systemic disease. Langerhans cell histiocytosis (LCH) is a rare cause and may precede systemic involvement by several years. Case: We report a 42-year-old male who presented in 2017 with polyuria and polydipsia, with urine output of up to 10 L/ day. AVP deficiency was confirmed by the water deprivation test, and desmopressin was initiated. Initial pituitary magnetic resonance imaging (MRI) was normal, baseline anterior pituitary hormonal evaluation was unremarkable, and contrast-enhanced computed tomography (CECT) of the thorax and abdomen showed no abnormalities. Repeat pituitary MRI 1 year later demonstrated loss of the posterior pituitary bright spot with pituitary stalk thickening. In the absence of systemic involvement, a presumptive diagnosis of lymphocytic hypophysitis was made, and pituitary biopsy was deferred due to the high procedural risk. Serial pituitary MRIs over the following years showed persistent infundibular thickening and continued absence of the posterior pituitary bright spot, without interval progression or development of additional hormonal deficiencies. The patient remained clinically stable until June 2024, when new-onset left hip pain prompted MRI, revealing a heterogeneous mass involving the femoral neck and intertrochanteric region with a pathological fracture. Histopathological examination following wide resection confirmed LCH, with negative BRAF V600 mutation. Postoperative PET scan revealed a multisystem disease involving the skeleton, lymph nodes, spine, and gastrointestinal tract, with no bone marrow involvement. He subsequently completed six cycles of intravenous methotrexate and cytarabine. Conclusion Adult-onset AVP deficiency may be the earliest manifestation of occult multisystem Langerhans cell histiocytosis. This case highlights the importance of longterm follow-up and reconsideration of the initial diagnosis when new systemic features emerge.
Histiocytosis, Langerhans-Cell

Introduction: Langerhans cell histiocytosis (LCH) is a clonal proliferative disorder of langerin-positive histiocytes. Endocrine involvement most frequently manifests as central diabetes insipidus or secondary hypothyroidism, caused by infiltration of the hypothalamic-pituitary axis. Conversely, direct infiltration of the thyroid gland leading to primary hypothyroidism is an exceptionally rare clinical entity, particularly when presenting concurrently with central disease. Case: A 21-year-old female with known right otic and multisystem LCH presented with septic shock secondary to a right ear abscess accompanied by polyuria and polydipsia. Physical examination revealed a palpable goiter. Clinical and biochemical evaluation confirmed central diabetes insipidus with associated anterior hypopituitarism (low adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone). However, concurrent thyroid function tests demonstrated overt primary hypothyroidism, evidenced by an appropriately elevated thyroid-stimulating hormone (26.19 mIU/L) and low free T4 (5.47 pmol/L), rather than the anticipated secondary hypothyroidism. Neck ultrasound showed diffuse thyroid enlargement with heterogeneous echotexture. Crucially, anti-thyroid peroxidase and anti-thyroglobulin antibodies were both negative, rendering Hashimoto’s thyroiditis highly unlikely. Although the patient declined confirmatory fine-needle aspiration, the constellation of a palpable goiter, characteristic ultrasonographic findings, negative autoimmunity, and active multisystem disease strongly supported a diagnosis of direct histiocytic infiltration of the thyroid gland. She was initiated on appropriate glucocorticoid coverage and subsequent levothyroxine replacement, alongside systemic intravenous cytarabine. Conclusion This case highlights a rare, mixed endocrine profile in multisystem LCH, demonstrating that pituitary and direct end-organ infiltration can coexist. Hypothyroidism in LCH patients with established central diabetes insipidus should not be reflexively assumed to be central in origin. A comprehensive diagnostic workup, including autoantibody screening, ultrasound, and ideally histopathological confirmation, is essential to accurately identify primary endocrine failure and guide appropriate clinical management in these complex cases.
Histiocytosis, Langerhans-Cell ; Hypothyroidism ; Pituitary Gland

Langerhans cell histiocytosis of bone is a rare tumor disease characterized by the large accumulation of CD1a⁺ and CD207⁺ dendritic cells in tissues of unknown cause.It mainly occurs in children aged 1-4 years old,with incidences of 4-6 per million in children and 1-2 per million in adults.Due to its low incidence,diverse clinical manifestations,and no obvious specificity of imaging manifestations,the definitive diagnosis and early treatment of this type of tumor are challenging.In this paper,we report 8 cases of Langerhans cell histiocytosis of bone and review the relevant literature published in the past five years to summarize the clinical characteristics,pathological features,diagnosis,treatment,and prognosis of this disease.
Humans ; Bone Diseases/therapy* ; Histiocytosis, Langerhans-Cell/therapy*

OBJECTIVES: To study the clinical characteristics, efficacy, and prognosis of pediatric Langerhans cell histiocytosis (LCH). METHODS: A retrospective analysis was conducted on 72 children with newly diagnosed LCH. RESULTS: The median age of the 72 children was 5 years (range: 0-14 years), with skull involvement being the most common (56 cases, 77.8%). The BRAF-V600E mutation was not associated with clinical characteristics, efficacy, or prognosis (P>0.05). The 5-year overall survival rate was 91.6%±4.2%, and the 5-year event-free survival (EFS) rate was 67.5%±5.8%. The 6-week chemotherapy response rate and 5-year EFS rate were lower in the risk organ involvement group compared to the no risk organ involvement group (P<0.05). The five-year overall survival rates for the group with multi-system involvement and the group with platelet count ≥450×10⁹/L were respectively lower than those for the single-system involvement group and the group with platelet count <450×10⁹/L (P<0.05). Risk organ involvement is an independent risk factor for 5-year EFS (P<0.05). CONCLUSIONS Skull is the most commonly affected site in pediatric LCH. The BRAF-V600E mutation is not related to clinical characteristics, efficacy, or prognosis. Elevated platelet count, risk organ involvement, and multisystem involvement are associated with poor prognosis, with risk organ involvement being an independent risk factor for 5-year EFS.
Humans ; Histiocytosis, Langerhans-Cell/therapy* ; Child, Preschool ; Child ; Male ; Infant ; Female ; Adolescent ; Retrospective Studies ; Proto-Oncogene Proteins B-raf/genetics* ; Prognosis ; Infant, Newborn ; Mutation

This report describes a case of adult temporal bone Langerhans cell histiocytosis（LCH） that presented as posterior canal dehiscence syndrome（PCDS）. The patient initially presented with vertigo, tinnitus, and hearing loss. Computed tomography（CT） revealed erosive changes in the mastoid and posterior semicircular canal. After the operation, the patient's hearing and vestibular symptoms disappeared and postoperative recovery was favorable. Adult LCH is relatively rare, and this case serves as an example to discuss the clinical features and treatment options of this disease, followed by a literature review.
Humans ; Histiocytosis, Langerhans-Cell/complications* ; Semicircular Canal Dehiscence/etiology* ; Temporal Bone/pathology*

OBJECTIVE

To present a case of Langerhans cell histiocytosis mimicking bilateral otitis media and acute mastoiditis in a one-year-old girl, and to discuss the clinical presentation, diagnostic dilemma, management and prognosis of this disease.

Design: Case Report

Setting: Tertiary Private Teaching Hospital

Patient: One

A one-year-old girl with a three-month history of bilateral otorrhea, post-auricular lymphadenopathies and dermatitits unresponsive to multiple courses of antibiotics, developed osseous and soft tissue destruction around the temporal and occipital bones. Her multiple progressive symptoms eventually led to the diagnosis of Langerhans cell histiocytosis.

Langerhans cell histiocytosis is a multifocal disease that can present with ear symptoms and can cause management dilemmas. It may mimic acute or chronic infections of the ear and should be suspected when extensive bone erosion is present.

Langerhans Cell Histiocytosis (LCH) is a rare disorder characterized by the abnormal proliferation of histiocytes, predominantly affecting the bones and skin. However, it can also involve the bone marrow, liver, spleen, lungs, pituitary gland, central nervous system, and other organs. The disorder is named for the neoplastic cells that resemble dendritic Langerhans cells found in the skin and mucosa.

We present the case of a 2-year-old Filipino female diagnosed with recurrent LCH, highlighting the diagnostic challenges and therapeutic interventions encountered. The patient initially presented with characteristic papules and plaques indicative of LCH. Initial treatment involved multi-agent chemotherapy, which resulted in significant clinical improvement. However, following the cessation of therapy, the patient experienced recurrence of symptoms, necessitating reevaluation. A skin punch biopsy confirmed the diagnosis of LCH, reinforcing the decision to reinitiate chemotherapy. Complications arose during treatment, including febrile neutropenia, which required hospitalization and adjustments to the management plan. After completing the chemotherapy cycles, the patient demonstrated marked clinical improvement, with the resolution of systemic symptoms and a reduction in the severity of cutaneous lesions.

This case underscores the complexities in managing recurrent LCH in pediatric patients. A comprehensive diagnostic evaluation, vigilant monitoring for treatment-related complications, and prompt therapeutic interventions are critical for achieving optimal outcomes. Effective management requires a multidisciplinary approach to address the unique challenges presented, ensuring timely interventions to improve patient outcomes.

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia affecting children 2-5 years old. The clinical presentation ranges from self-resolving localized disease to fulminant, fatal disseminated disease. While the most common presentation of LCH are small, translucent crusted papules on the trunk, intertriginous areas, and scalp, it may present as crusted plaques and alopecia. A 3-year-old male presented with a 4-month history of solitary, well-defined, hyperpigmented plaque with yellow-brown crust on the left parieto-occipital area of the scalp measuring 1.5 x 1.5 cm and a solitary, well-defined, hairless patch with areas of erythema on the left parieto-occipital area measuring 5.0 x 6.0 cm. Scalp biopsy revealed diffuse collection of lymphohistiocytes interspersed with distinct kidney bean-shaped cells. CD1a is positive for cells of interest. Skeletal survey revealed lytic lesions involving the skull, thoracic cage, spine, pelvis, and upper and lower extremities. The rest of the physical examination findings revealed lymphadenopathy, crackles, globular abdomen with right and left upper quadrant dullness. The patient had episodes of fever, difficulty of breathing, and abdominal pain. The patient received chemotherapy as multisystem LCH based on prednisone and vinblastine. Following 3 courses of chemotherapy, there is noted hair regrowth and sloughing off of crust.

Humans ; Histiocytosis, Sinus/diagnosis* ; Fractures, Compression/complications* ; Diagnosis, Differential

Humans ; Histiocytosis ; Receptor Protein-Tyrosine Kinases