Berbeck's granules are seen in

Ans. a (Langerhan cells). (Ref. Robbins, Pathologic Basis of Disease 6th/pg.685)HISTIOCYTOSIS# Histiocytosis represents clonal proliferation of antigen- presenting dendritic cells.# It is of two types:- Localized histiocytosis (70%) i.e. Eosinophilic granuloma. It is the most benign variety of langerhans cell histiocytosis.- Disseminated histiocytosis (30%)i. Hand - Schuller - Christian disease (chronic)ii. Letterer-Siwe disease (fulminant)# Age: 5-10 years most common# Location: Bone (in children) or lung (in adults) most commonly involved.# Sites of infection:- Flat bones: calvarium > mandible > ribs > pelvis > vertebrae- Long bones- Skull: Diplopic space of parietal bone (most common) affected.i. Round/ovoid punched out lesion with beveled edge ('Hole within hole' appearance) with sharply marginated without the sclerotic rim with "button sequestrum" with soft tissue mass overlying lesion (geographic skull).- Jaw: Floating tissue mass overlying lesion- Vertebra plana- Painful diaphyseal expansile lytic long bone lesions.# Pathology:- Birbeck's granules/HX bodies are characteristic pathologic feature of histiocytosis X, noted in cytoplasm of Langerhan cells.- On electron microscope they have 'tennis-racket' appearance.- These tumor cells typically express HLA-DR and CDla.DISEASESCELLULAR CHARACTERISTICS OF THE LESIONSTREATMENTClass 1(Langerhans cell histiocytosis )Langerhans cells (CDla positive) with Birbeck granulesLocal therapy for isolated lesions; chemotherapy for disseminated disease.Class II(Infection-associated hemophagocytic syndrome)Morphologically normal reactive macrophages with prominent erythrophagocytosisChemotherapy; allogeneic bone marrow transplantation.Class III (Malignant histiocytosis)Neoplastic proliferation of cells with characteristics of monocytes/ macrophages or their precursors iAntineoplastic chemotherapy, including - methotrexate, vincristine, etoposide, imatinib....are being tried.