This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Pathology
[{'content': 'A 24-year-old woman presents with an earache of 4 days in duration. She also reports increased urine production, a skin rash, and bone pain on her scalp. Physical examination reveals otitis media, dermatitis, and exophthalmos. An X-ray of the scalp shows calvarial bone defects. A fine-needle aspirate displays numerous eosinophils. Which of the following is the most likely diagnosis? \nSelect and explain. \nA. Hodgkin lymphoma, B. Langerhans cell histiocytosis, C. Malignant melanoma, D. Metastatic breast carcinoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: LCH refers to a spectrum of uncommon proliferative disorders of Langerhans cells. The disease ranges from asymptomatic involvement of a single site, such as bone or lymph nodes, to an aggressive systemic disorder that involves multiple organs. There is clinical heterogeneity of LCH; eosinophilic granuloma (75% of all cases) is a localized, usually self-limited disorder of older children and young adults; Hand-Schuller-Christian disease is a multifocal and typically indolent disorder, usually in children between 2 and 5 years of age; and Letterer-Siwe disease (fewer than 10% of cases) is an acute, disseminated variant of LCH in infants and children younger than 2 years of age. Organs involved by LCH include the skin (seborrheic or eczematoid dermatitis), lymph nodes, spleen, liver, lungs, and bone marrow. Otitis media is a common finding. Painful lytic lesions of bone are common. Proptosis may complicate infiltration of the orbit. The classic triad of diabetes insipidus, proptosis, and defects in membranous bones characterizes Hand-Schuller-Christian disease. Hodgkin lymphoma (choice A) often features eosinophils but does not have this clinical presentation.Diagnosis: Langerhans cell histiocytosis', 'role': 'assistant'}]