Role of the Thymus in Histiocytosis-X

Histologic patterns of thymic involvement in Langerhans cell proliferations: a clinicopathologic study and review of the literature

Thymic involvement by Langerhans cell histiocytosis (LCH) has been described mainly in isolated case reports. A description of the histopathologic patterns of LCH proliferations in the thymus, together with therapeutic implications, has not, to our knowledge, been previously addressed. The pathology consultation files at Children's Hospital of Pittsburgh of the University of Pennsylvania Medical Center were reviewed for cases of thymic involvement by LCH. Relevant cases in the literature were also reviewed, and the histopathology and clinical course of those cases were collected. Nine consultation cases of thymic involvement were reviewed, together with 23 cases in the literature, which provided adequate pathologic description and ancillary confirmation (n  =  32), revealing 4 distinct pathologic groups. Group 1 showed microscopic collection of hyperplastic LCH-like cells in incidental thymectomies of patients without LCH disease, requiring no further treatment (n  =  7; 22%). Group 2 showed solitary and/or cystic LCH of the thymus with gland disruption, and at least 3 cases resolved without systemic therapy (n  =  10; 31%). Group 3 showed more variable thymic involvement in multisystemic LCH disease, with either a medullary restricted pattern or more diffuse gland involvement, requiring adjuvant therapy and having a higher mortality rate (n  =  13; 41%). Group 4 showed a mixed histiocytic lesion with a concurrent LCH and juvenile xanthogranuloma-like proliferation (n  =  2; 6%). Thymic involvement in LCH is quite rare. Based on our cases and those in the literature, we propose 4 distinct pathologic groups of thymic involvement in Langerhans cell proliferations with relevance for diagnosis and treatment.

Radiological features of thymic langerhans cell histiocytosis

TI was reported in 18/1,264 (1.4%) LCH patients. All nine patients with TI at initial LCH presentation were below 2 years of age and had multisystem LCH (9/242, 4%). Images (sonography, CT, MRI) for central review were available in 15 cases. Characteristic findings of TI were thymus enlargement (67%), few to many cysts (80%), and few to many calcifications (100%). Sonographic and MRI findings were in excellent agreement. We recommend adding sonography of the thymus to the standard for initial clinical evaluation of LCH patients below the age of 2 years.

Extraosseous langerhans cell histiocytosis in children

Langerhans cell histiocytosis, a rare disease that occurs mainly in children, may produce a broad range of manifestations, from a single osseous lesion to multiple lesions involving more than one organ or system. The clinical course varies widely in relation to the patient's age. Multisystem disease may demonstrate especially aggressive behavior in very young children, with the outcome depending largely on the stage of disease and the degree of related organ dysfunction at the time of diagnosis. Extraosseous manifestations are less commonly seen than osseous ones and may be more difficult to identify. To accurately detect extraosseous Langerhans cell histiocytosis at an early stage, radiologists must recognize the significance of individual clinical and laboratory findings as well as the relevance of imaging features for the differential diagnosis. The pattern and severity of pulmonary, thymic, hepatobiliary, splenic, gastrointestinal, neurologic, mucocutaneous, soft-tissue (head and neck), and salivary involvement in Langerhans cell histiocytosis generally are well depicted with conventional radiography, ultrasonography, computed tomography, and magnetic resonance imaging. However, the imaging features are not pathognomonic, and a biopsy usually is necessary to establish a definitive diagnosis.

A case of langerhans’-cell histiocytosis with membranous nephropathy

A 26-year-old man with a history of Langerhans'-cell histiocytosis (LCH) of the bone presented with nephrotic-range proteinuria. Renal biopsy results showed changes characteristic of membranous nephropathy. During the current hospitalization, the patient had 2 episodes of pulmonary embolism. LCH at this time was documented in the lymph nodes. The patient was treated with repeated courses of vinblastine and high doses of corticosteroids to achieve remission of the basic disease and the renal involvement. After 2 years, complete remission of both the lymphadenopathy and the nephrotic syndrome was achieved. The association of membranous nephropathy with LCH might be attributable to an underlying abnormality in the immune system, a paraneoplastic manifestation, or both. This is the first report of LCH associated with severe nephrotic syndrome caused by membranous nephropathy.

Langerhans cell histiocytosis patients have HLA Cw7 and DR4 types associated with specific clinical presentations and no increased frequency in polymorphisms of the tumor necrosis factor alpha promoter

BACKGROUND

Current theory on the etiology of Langerhans cell histiocytosis (LCH), formerly Histiocytosis-X, is that abnormality(ies) of the immune system are responsible for dysregulation of Langerhans cells (LC) in patients' lesions. Among the known abnormalities in LCH patients are increased amounts of tumor necrosis factor alpha (TNF-alpha) and other cytokines in the lesions.

PROCEDURE

We investigated the human leukocyte antigen (HLA) phenotypes of 29 patients and 37 healthy family members to determine if any haplotypes segregate with the presence or locations of the disease. The lymphocyte subsets for 22 patients and 11 family members were also determined.

RESULTS

Patients with single bone, multiple bone, or multi-system LCH had different relative proportions of HLA types. Patients presenting with single bone disease had an especially high frequency of the DR4 type. In this patient group, every Caucasian patient had either Cw7 or DR4. Lymphopenia was documented in patients who had been off therapy as well as those who only had surgical curetage of their lesions. Family members also had low numbers of T lymphocytes. There were fewer mutations of the TNF-alpha promoter in patients than in the general population.

CONCLUSIONS

Although there is an increased percentage of LCH patients with DR4 and/or Cw7 there was also an increased prevalence of this antigen as well as lymphopenia among unaffected family members. Additional genetic and/or environmental factors are necessary to explain this association. TNF-alpha promoter mutations are not responsible for the increased production of this cytokine.

Detection of Langerhans cell histiocytosis lesions with somatostatin analogue scintigraphy--a preliminary report

BACKGROUND

Langerhans cell histiocytosis (LCH) is a disease where granulomatous lesions occur in various organs of the body. The etiology and pathogenesis remain unknown. Inflammatory destructive activity give rise to a wide range of clinical symptoms, including fractures, skin lesions, pulmonary fibrosis, endocrinopathies, and central nervous system deterioration. Since disease activity may ultimately lead to fibrosis and organ damage, it is important to have diagnostic tools to detect disease activity early.

PROCEDURE

The present study was undertaken in order to evaluate whether somatostatin analogue scintigraphy ((111)In-pentetreotide or OctreoScan could be used in detecting LCH granulomas and to compare this method with the radiologic methods used today in LCH diagnosis and follow-up. The somatostatin analogue octreotide used here binds to the cell membrane of activated lymphocytes expressing somatostatin receptors.

RESULTS

In five out of six children studied, LCH lesions detected by other means were also detected with (111)In-pentetreotide. It can be speculated that the lesion in the remaining patient was not active at the time of investigation. In addition, in two of the patients signs of disease activity not previously known were revealed.

CONCLUSION

(111)In-pentetreotide can be used to detect active LCH lesions. Since the biologically active somatostatin analogue decreases inflammatory activity, this may also be of therapeutic value in selected patients with LCH. More studies are needed to evaluate the diagnostic and potential therapeutic usefulness of this radionuclide.

The epidemiology of Langerhans cell histiocytosis

Little progress has been made in finding the causes of LCH. Epidemiologic studies are difficult because of the rarity of this disease. Although several associations have been demonstrated in case-control studies, particularly that with thyroid disease, no causal relationships have been documented. Additional case-control studies may uncover the to-date missing lead that may prove fruitful for epidemiologic investigation.

An update on clonality, cytokines, and viral etiology in Langerhans cell histiocytosis

Many etiologies have been proposed for Langerhans cell histiocytosis (LCH). Recent scientific studies have clearly provided new insights into the etiology and pathogenesis of the disease. The possible role of viruses has not been completely negated, but no viral genomes have been consistently detected in LCH lesions. Other studies do not indicate that LCH arises from a primary defect in the immune system, although altered immune responses and immune dysfunction may play a role in the pathophysiology of the disease. Definitive results have been gained from molecular studies of clonality, however. These have definitively established that LCH is a clonal histiocytic disease rather than a reactive polyclonal disorder.

Langerhans cell histiocytosis associated with partial DiGeorge syndrome in a newborn

PURPOSE

We report the unrecognized association of Langerhans cell histiocytosis (LCH) with partial DiGeorge syndrome.

PATIENT AND METHODS

A 7-week-old infant with endocrine and immunologic characteristics of DiGeorge syndrome displayed multisystem involvement of Letterer-Siwe disease at birth.

RESULTS

Despite vigorous medical support and chemotherapy, she died at 9 months of age with multisystem failure.

CONCLUSIONS

This case supports the role of the thymus n the pathogenesis of LCH.

Langerhans cell histiocytosis

The first major stride toward understanding LCH was taken when ultrastructural studies identified the proliferating cells as part of the Langerhans (dendritic) cell system. Another step forward was the definition of the morphologic, immunohistochemical, and clinical criteria needed for the diagnosis of LCH. Meanwhile, modern imaging studies have disclosed lesions that were not previously visible, especially those in the brain and the pituitary gland. These advantages have had a major impact on clinical management by making it possible to compare data from different institutions and to centralize coherent clinical and therapeutic data. Moreover, the agreement concerning diagnostic criteria provides a solid foundation for current clinical trials and for laboratory research regarding the possible roles of the immune system, clonality, and cytokines in the etiology of LCH.

Treatment of Langerhans-cell histiocytosis in children. Experience at the Children's Hospital of Nancy

Forty children who had Langerhans-cell histiocytosis were followed for an average of six years (range, excluding patients who died of the disease, two to fifteen years). The patients were divided into two diagnostic groups: those who had localized disease (involving one bone or more only) and those who had multifocal disease (an osseous lesion and a soft-tissue mass, a skin rash, diabetes insipidus, or generalized disease). Methods of treatment included curettage, bone-grafting, chemotherapy, local or systemic corticosteroids, and radiotherapy. Nineteen of the thirty patients who had localized disease had a complete response to the therapy, four had a partial response, and seven had no response. Twenty-one of these thirty patients had not had a recurrence by the time of the latest follow-up examination; nine had a local recurrence within four years after the initial therapy but had no additional recurrences after treatment of the local recurrence. No recurrence occurred more than four years after the time that the initial diagnosis had been made. Five of the ten patients who had multifocal disease had a complete response to the therapy, two had a partial response, and three had no response. Six patients had a recurrence; four did not. Two patients died of the disease. As a result of this study, we recommend the avoidance of intensive measures of treatment, if possible, and we advise long-term follow-up of these patients.

Langerhans' cell histiocytosis in association with periapical granulomas and cysts

This report describes a series of six cases of inflammatory periapical disease with small aggregates of Langerhans cells as a minor component. Immunohistochemical findings confirm that the cells are phenotypically related to Langerhans cells. Aggregates of these cells are not normally found in radicular cysts or periapical granulomas and have been interpreted to represent chronic localized Langerhans' cells histiocytosis. Whether these lesions, which arise within the context of chronic inflammatory periapical disease, represent incipient eosinophilic granulomas or are a more benign, minimally destructive form of Langerhans' cell histiocytosis is unknown. Clinical follow-up suggests that these lesions remain localized and that curettage is adequate treatment.