Micrograph showing<unk> . H&E stain. Diagnosis is confirmed histologically by tissue biopsy. Hematoxylin-eosin stain of biopsy slide will show features of Langerhans Cell e.g. distinct cell margin, pink granular cytoplasm. Presence of Birbeck granules on electron microscopy and immuno-cytochemical features e. g. CD1 positivity are more specific. Initially routine blood tests e.g. full blood count, liver function test, U&Es, bone profile are done to determine disease extent and rule out other causes. Imaging may be evident in chest X-rays with micronodular and reticular changes of the lungs with cyst formation in advanced cases. MRI and High-resolution CT may show small, cavitated nodules with thin-walled cysts. MRI scan of the brain can show three groups of lesions such as tumourous/granulomatous lesions, nontumourous/granulomatous lesions, and atrophy. Tumourous lesions are usually found in the hypothalamic-pituitary axis with space-occupying lesions with or without calcifications. In non-tumourous lesions, there is a symmetrical hyperintense T2 signal with hypointense or hyperintense T1 signal extending from grey matter into the white matter. In the basal ganglia, MRI shows a hyperintense T1 signal in the globus pallidus. Assessment of endocrine function and bonemarrow biopsy are also performed when indicated. * S-100 protein is expressed in a cytoplasmic pattern * peanut agglutinin (PNA) is expressed on the cell surface and perinuclearly * major histocompatibility (MHC) class II is expressed (because histiocytes are macrophages) * CD1a * langerin (CD207), a Langerhans Cell–restricted protein that induces the formation of Birbeck granules and is constitutively associated with them, is a highly specific marker.
Langerhans cell histiocytosis
X-type histiocytosis
Sea-blue histiocytosis
Malignant histiocytosis
Crystal-storing histiocytosis
Non-X histiocytosis
Progressive nodular histiocytosis
Langerhans cell sarcoma