Langerhance Cell Histiocytosis (LCH) 5 Years After B-cell Acute Lymphoblastic Leukemia in a 11 year-old boy Professor. Ansari Professor of pediatric hematology and oncology Dr. Neda Ashayeri Fellow of of pediatric hematology and oncology Ali-Asghar children hospital

LCH Rare disease that involving the proliferation of cells similar to Langerhans cells of epidermis S100 positivity, CD 1a expression and Birbeck granules. Associated with a variety of malignancies. During or after the treatment of acute leukemia is rare.

LCH has preceded the diagnosis of leukemia or occurred within 6-12 months after diagnosis of leukemia. We report a case of LCH with one lesion in skull bone in a patient 5 years after completion of chemotherapy of ALL.

Case 11-year-old boy Oncology ward of Ali-Asghar children hospital A local pitting region on the left side of the head Past medical history: Pre B-cell ALL at age 3 years old. At that time: WBC 139000/mm3, Hb level 4.3g/dl, and platelet count 12000/ul. On flow cytometry at diagnosis the leukemic blasts showed expression of CD10, CD19, CD20, and HLA-DR consistent with a precursor B cell phenotype

Bone scan: only involvement of the left parietal bone without any other bony lesion. Chest X-ray: normal. Results of CBC, LFT, and urinalysis: normal. Polydipsia or polyuria: Neg Skull X-ray: a small lytic lesion MRI: 21*24*29mm enhancing mass at the left parietal bone. Excision of the lesion: LCH was confirmed by pathologyc and histology findings

For treatment of LCH, he received vinblastine, methotrexate, 6-mercaptopurine and prednisolone. The disease completely resolved. Follow-up imaging MRI and X-ray have shown only reduction of his bony skull lesion.

Discussion It seems that the occurrence of LCH and malignant disease in the same individual is not by chance alone. Egeler et al described 54 LCH patients under 18 years of age and history of malignant disease. Of theses subjects: 29 had acute leukemia. Others: Hodgkin’s and non-Hodgkin’s lymphoms, retinoblastomas, medulloblastomas, osteosarcomas and basal cell carcinoma.

Of 29 patients with acute leukemia: 12 had ALL In 7 of the 12 ALL patients: LCH developed 6 to 12 months after the diagnosis of ALL, while all of them were still receiving chemotherapy. In the other 5 ALL patients: LCH preceded the diagnosis of ALL. There is a report of LCH developing in a patient with history of B-ALL after completion of chemotherapy. It was a 7-year-old boy with a localized form of LCH with 2 bone lesions who had previously had B-ALL when he was 2-year-old. The difference in patient of the present study was the period between ALL and LCH that was 5 years in the present case and 2 years in the other case.

Development of LCH was 5 years after completion of chemotherapy, so: it is less likely to be secondary to chemotherapy- induced immune suppression. As a functioning immune system is re-established by 6 months after completion of chemotherapy.

Trebo in a retrospective study found that: 6 of the 971 T-ALL patients that registered in BFM-ALL trial developed HLH (4 patients) or LCH. (2 patients) They suggested that younger age and high initial leukocyte count maybe are risk factors for development of histiocytic complication. In this proposed case, young age and high initial leukocyte persisted in initial admition for ALL

The time interval between T-ALL and LCH in that study was 2 The time interval between T-ALL and LCH in that study was 2.6 years that was shorter than our B-ALL patient. On the other hand, it seems that AML, appeared some time after the diagnosis of histiocytosis. Epipodophylotoxin, one of the drugs that used to treat LCH, is thought to be responsible in some of these cases of AML.

Gaixiang and their colleagues reported a rare case of solitary LCH involving the femur of an adolescent who was diagnosed AML 15 months after the onset of LCH without any chemotherapy for LCH. LCH was treated only by surgery. They suggested that the onset of AML in the patient of LCH is not only associated with chemotherapy, certain underlying mechanism may exist Successful treatment of a case of acute myeloid leukemia following Langerhans cell histiocytosis in an adolescent: a case report and review of the literature. Int J Clin Exp Med 2015;8(2):3024-3026

The association of ALL and LCH Is not clearly defined but it may be related to a common stem cell defect of lymphoid and dendritic precursors or it may be due to pogenetic predisposition of ALL and LCH. Another hypothesis is that LCH developed from chemotherapy but in this report it was unlikely because of long time between completion of chemotherapy and LCH. Finally, It would be highly valuable to identify clinical or pathological risk factors of leukemia or typical symptoms in the follow up that can predict the development of a histiocytic disorder.

conclusion Finally, It would be highly valuable to identify clinical or pathological risk factors of leukemia or typical symptoms in the follow up that can predict the development of a histiocytic disorder. We recommend close follow up especially for young ALL patients.

Thank you