Acute myeloid leukemia and Langerhans’ cell histiocytosis: Multiple theories for an unusual presentation

Spectrum of second primary malignancies and cause-specific mortality in pediatric and adult langerhans cell histiocytosis

With the advent of targeted therapeutics in Langerhans cell histiocytosis (LCH), there is a growing survivor population that might be at risk for late mortality from non-LCH causes, including second primary malignancies (SPMs). We undertook a large study using the Surveillance, Epidemiology, and End Results (SEER) database to evaluate the patterns of SPMs and cause-specific mortality among individuals with LCH (2000-2016) from the US. We found an increased risk of SPMs in the cohort (standardized incidence ratio [SIR] 2.07). The pediatric group was at a high risk of developing Hodgkin lymphoma (SIR 60.93) and non-Hodgkin lymphoma (SIR 60.88). People with adult-onset LCH were found to have a high risk of developing miscellaneous malignant cancers (SIR 11.43), which primarily included myelodysplastic syndrome. Adults were also at a high risk of developing carcinoma in-situ of vulva at 2-11 months [SIR 62.72] and B-ALL at 60-119 months [SIR 66.29] after LCH diagnosis. Additionally, 5% and 1% of the patients developed prior or concomitant malignancies with LCH, respectively. The 5 yr overall survival (OS) was 96.6% for pediatric and 88.5% for adult LCH cohorts. Most common cause of death was infections in pediatric and SPMs in adult LCH. Our study highlights that despite advances in treatments, people with LCH have an increased mortality risk from non-LCH causes when compared with the general population, including a high risk of SPMs.

Langerhans cell histiocytosis: A great imitator

Langerhans cell histiocytosis (LCH) is an uncommon but serious inflammatory neoplasia that affects many organs, including the skin. Though uncommon, it should remain high on a clinician's differential diagnosis in treatment-resistant cases of conditions, such as seborrheic dermatitis, diaper dermatitis, arthropod bites, and many more. A thorough history nd physical examination for each patient can aid in the diagnosis; however, if clinically suspicious for LCH, a punch biopsy should be performed. Histologic evaluation of LCH is often enough to differentiate it from the many clinical mimickers. Characteristic findings include a histiocytic infiltrate with "coffee bean"-cleaved nuclei, rounded shape, and eosinophilic cytoplasm. Immunohistochemical stains, including CD1a, S100, and CD207 (langerin) are often needed for a definitive diagnosis. Electron microscopy also demonstrates the ultrastructural presence of Birbeck granules, but this is no longer needed due to immunohistochemical staining. Treatment is often necessary for LCH, if systemic involvement exists.

Langerhans Cell Histiocytosis Associated With Underlying Hematolymphoid Disorders in Adults: Report of 2 Cases and Review of the Literature

Langerhans cell histiocytosis (LCH) is an uncommon disorder characterized by proliferation of abnormal LCs usually affecting children and adolescents. LCH in adults first presenting in the skin is rare. Although LCH and even LCH with a second malignancy may be more common in children, cutaneous LCH with a second hematologic malignancy has been more commonly identified in adults. The authors report 2 new cases of LCH in adult patients with underlying myelodysplasia and follicular lymphoma. The specimens were examined by routine microscopy and immunohistochemical stains for S100 protein and CD1a. Patients were elderly men with established diagnoses of follicular lymphoma and myelodysplasia, presented with follicular lesions and erythematous plaques involving intertriginous areas. Histologic examination revealed collections of mononuclear cells in upper dermis, which demonstrated strong positivity for S100 and CD1a, confirming their identity as LCs. BRAF analysis returned negative for detection of BRAF V600E mutation in both patients. The authors have recently encountered 2 cases of adult patients with skin-limited LCH predated by other lymphoproliferative disorders. The association between LCH and hematopoietic disorders may be explained by a common bone marrow precursor that is differentiating along different cell lines. Cutaneous LCH may be associated with underlying lymphoproliferative disorders and should be considered in the differential diagnosis of cutaneous eruptions in patients with hematopoietic disorders. Clinical follow-up evaluation of patients diagnosed with LCH for peripheral blood abnormalities and lymphadenopathy or "B symptoms" may be prudent in patients not already carrying a diagnosis of an underlying hematologic disorder.

Langerhans Cell Sarcoma in a Chronic Myelogenous Leukemia Patient Undergoing Imatinib Mesylate Therapy

Langerhans cell sarcoma (LCS) is a rare malignancy requiring differential diagnosis from other high-grade nonhematologic and hematologic tumors. The pathogenesis of LCS remains unknown. Notably, LCS and its benign counterpart, Langerhans cell histiocytosis (LCH), are frequently associated with other malignancies. To the best of our knowledge, we describe the first case of LCS in a chronic myelogenous leukemia (CML) patient undergoing imatinib mesylate therapy. We performed molecular cytogenetic analyses for investigating the association between LCS and CML. In our case, molecular cytogenetic analysis did not reveal BCR-ABL1 fusion and BRAF V600E mutation, suggesting that LCS may be coincident in this patient. However, recurrent BRAF V600E mutation has been found in LCH. Published reports have revealed the clonal relationship between LCH/LCS and other hematologic malignancies, especially lymphoid neoplasms. However, there are only 2 reports demonstrating the clonal relationship between LCH and myeloid neoplasms. The association of LCH/LCS with myeloid neoplasms and the role of BRAF V600E mutation in LCS are discussed.

Langerhans cell histiocytosis first presenting in the skin in adults: frequent association with a second haematological malignancy

BACKGROUND

Langerhans cell histiocytosis (LCH) in adults first presenting in the skin is rare. Guidelines for staging, treatment and follow-up are lacking.

OBJECTIVES

To better define staging procedures, treatment results and clinical course in adult patients with LCH first presenting in the skin.

METHODS

Eighteen adult patients with LCH first presenting in the skin were collected from five centres collaborating in the Dutch Cutaneous Lymphoma Group. Clinical records and (skin) biopsy specimens were reviewed and follow-up data were obtained. A literature search on adult patients with LCH presenting in the skin was performed.

RESULTS

Staging procedures showed extracutaneous disease in three of 16 patients who were adequately staged. One patient had a histologically confirmed lytic LCH bone lesion, while two patients had a myelodysplastic syndrome. During follow-up two of 18 patients developed extracutaneous localizations of LCH. Five patients developed a second haematological malignancy, including (myelo)monocytic leukaemia (two cases), histiocytic sarcoma (one case), diffuse large B-cell lymphoma (one case) and peripheral T-cell lymphoma (one case). Review of the literature revealed six other adult patients with a second haematological malignancy preceding or following a diagnosis of LCH.

CONCLUSIONS

The results of the present study suggest an increased risk of a second haematological malignancy in adult patients with LCH presenting in the skin. Extensive staging at presentation and long-term follow-up are therefore warranted in such patients.

Acute Myeloid Leukemia With t(9;11) (p22;q23) and Synchronous Langerhans Cell Histiocytosis

We present here the first report of an adult patient with simultaneous LCH and AML with t(9;11).5

Tumorous proliferations of plasmacytoid dendritic cells and Langerhans cells associated with acute myeloid leukaemia

AIMS

Proliferation of plasmacytoid dendritic cells (PDCs) occurs in both reactive lymphoid hyperplasia and myeloproliferative disorders, especially chronic myelomonocytic leukaemia. PDCs in the former appear reactive, but in the latter are reported to be clonally related to the underlying myeloid neoplasm. Langerhans cells (LCs), another type of dendritic cell, also proliferate in both reactive dermatoses and, rarely, myeloproliferative disorders, such as acute leukaemia.

METHODS AND RESULTS

We report a rare case of tumorous proliferation of PDCs and LCs in the systemic lymph nodes in a 55-year-old man with acute myeloid leukaemia. A microsatellite instability assay showed identical patterns of short tandem repeats in both microdissected PDC and LC components, along with blood blasts.

CONCLUSIONS

We hypothesize that the combined proliferations of PDCs and LCs derive from the same haematopoietic stem cells, but that they differentiate divergently under the effect of different microenvironments.