Macrophage In<unk> , histopathology studies reveal macrophages with an epithelioid shape, small nucleoli and round or oval nuclei. The cytoplasm of these macrophages contains<unk> s which are eosinophilic. The macrophages tend to be negative for S100 protein, CD1a, Langerin, and cytokeratin when immunohistochemically tested, but positive for CD68.<unk> s range in size from microscopic to 4 cm, and are dense, membrane bound and elongated, rectangular and/or rhomboid in shape. The<unk> s do not birefringe and are negative when stained with Congo red stain, but may be positive by phosphotungstic acid hematoxylin and periodic acid-Schiff (PAS) staining. The most common immunoglobulin deposited in the<unk> s is IgG. When the antibodies in the<unk> s are tested, they are almost always kappa light chain positive. The most common locations for<unk> s to form are bone, head and neck, kidney, lung and GI tract. When the<unk> s form in the kidney, they are often deposited in the tubulointerstitium. Immunofluorescent testing, with antibodies against immunoglobulins, may be useful in patients with kidney<unk>  deposits. Dogan et al. proposed a two-part classification of<unk> , dividing cases into localised or generalised. In localised disease,<unk> s are confined to one site, while in generalised disease, more than one site has<unk> -deposits. Around three quarters of cases are localised, with the remaining quarter showing signs of generalised disease. Patients with localised disease tend to have better outcomes.
Crystal-storing histiocytosis
Sea-blue histiocytosis
X-type histiocytosis
Langerhans cell histiocytosis
Non-Langerhans cell histiocytosis
Non-X histiocytosis
Malignant histiocytosis
Progressive nodular histiocytosis