Langerhans cell histiocytosis with histopathological features, single center experience Histopatolojik özellikleriyle langerhans hücreli histiyositoz, tek merkez deneyimi

Langerhans cell histiocytosis (LCH) is a rare histiocytic disease, occurring in 2-10 children per million and 1-2 adults per million, and may have a wide variety of clinical manifestations. Infiltration can develop in almost any organ (the most commonly reported organs are bone, skin, lymph nodes, lungs, thymus, liver, spleen, bone marrow and central nervous system). We aimed to evaluate the histopathological features of the lesions and review the literature in pediatric patients referred to our department for pathological examination and diagnosed as LCH. Materials and Methods: Retrospectively, childhood cases diagnosed with LCH in 2012-2019 were screened by hospital automation system. Age, gender, lesion localizations of the cases were recorded and histopathological features were reviewed. Results: 5 male and 5 female total of 10 cases were detected. The youngest 3 were under the age of 1, the oldest was 16 years old. Localization; 6 of the cases were bone (2 femur, 3 skull bone, 1 scapula), 2 skin, 1 bone and lymph node, 1 lung and lymph node. Histopathology revealed histiocytic cells with grooved nuclei, eosinophilic cytoplasm with eosinophils, and neutrophils in some cases. Immunohistochemical CD1a staining was positive in all cases and positivities were present with S100 in applied 9 cases, CD68 in 4. Ki67 proliferation index was studied in 2 patients with bone localization, 15% and 20%. Conclusion: The term LCH is due to the morphological and immunophenotypic similarity of the infiltrating cells of this disease to Langerhans cells specialized as dendritic cells in the skin and mucous membranes. But these cells do not originate from the Langerhans cells of the skin, but from the myeloid progenitor cells of the bone marrow. Several studies have shown the BRAF-V600E mutation in LCH. The term LCH is currently recommended; histiocytosis-X, Letterer-Siwe disease, Hand-Schuller-Christian disease and diffuse reticuloendotheliosis were abandoned. The term eosinophilic granuloma may be used in the presence of a single lesion, especially in lytic bone lesions. As in our cases, it usually occurs with single or multiple osteolytic bone lesions and to a lesser extent with other organ involvement. It is characterized by infiltration of grooved nuclei histiocytes, accompanied by lymphocytes, neutrophils, macrophages and eosinophils, and areas of fibrosis and necrosis may develop. Immunohistochemical S100, CD1a, Langerin are positive, CD68 is variable. In the differential diagnosis, acute myelomonocytic leukemia, lymphoma, mastocytosis, osteomyelitis, sinus histiocytosis with massive lymphadenopathy should be considered.