Histiocytosis-X: in situ characterization of cutaneous infiltrates with monoclonal antibodies

Langerhans cell histiocytosis of the maxillae in a child treated only with chemotherapy: a case report

Background

Langerhans cell histiocytosis is a sporadic disease caused by an uncontrolled pathogenic clonal proliferation of dendritic cells that have Langerhans cell characteristics. New treatment protocols provided by the HISTSOC-LCH-III (NCT00276757) trial show an improvement in the survival of children with langerhans cell histiocytosis.

Case presentation

We report a case of Langerhans cell histiocytosis, which presented as an osteolytic lesion of the left pre-maxillae enclosing the deciduous incisor and canine in a 7-month-old white Italian boy. He was treated with chemotherapy. He achieved complete remission after 7 months and after 24 months no signs of recurrence were observed.

Conclusions

As a result of this treatment, anesthetic sequelae and loss of teeth were avoided; in addition, we prevented a loss of the vertical dimension of occlusion.

Pathogenesis of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) combines in one nosological category a group of diseases that have widely disparate clinical manifestations but are all characterized by accumulation of proliferating cells with surface markers and ultrastructural features similar to cutaneous Langerhans cells (LCs). Despite this unified nosology, important questions about LCH remain unanswered. First, despite having phenotypic features of LCs, LCH cell gene-expression patterns differ from those in LCs. Although this observation suggests that LCH may arise from an earlier precursor, it is not necessarily inconsistent with the hypothesis that LCs are the cell of origin for LCH. Second, LCH's prominent inflammatory component and occasional benign clinical course suggest that LCH may not be a neoplasm. However, the demonstration that LCH cells are clonal, along with the recent discovery of activating BRAF mutations in LCH cells, strongly suggests that LCH is a neoplastic disease. These new observations point the way to rationally targeted therapies.

Recent advances in the understanding of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a proliferative disease of cells that share phenotypic characteristics with the primary antigen presenting cells of the epidermis. Its clinical manifestations are highly variable, extending from very benign forms to a disseminated, aggressive disease that causes significant mortality. Although many of the fundamental pathogenetic features of LCH have been enigmatic, recent advances have led to a much clearer understanding of the disease. In particular, careful molecular analyses of mouse models and human LCH samples suggest that LCH's cell of origin may not be the epidermal LC itself but a myeloid-derived precursor. Advanced genomic technologies have revealed the presence of activating, somatic BRAF mutations in the majority of patient specimens. Together, these observations have produced a new picture of LCH as a myeloid neoplasm. These advances are likely to have profound implications for the use of targeted therapeutics in LCH.

Xanthoma disseminatum in a pair of blind, deaf male twins

Xanthoma disseminatum (XD) is a rare normolipemic histiocytic disorder of non-Langerhans cell origin characterized by erythematous to tan/brown papules in flexor surfaces. Considered a generally benign, chronic disease of unknown etiology, XD typically affects the skin, mucous membranes, and less commonly, other organs. To date, there has been no typical or consistent inheritance pattern described, nor has it ever been considered as a component of any known syndrome. We describe, for the first time, two cases of XD in a pair of blind and deaf twin brothers.

Xanthoma disseminatum: a case report and literature review

This case report describes the neuro-opthalmologic and respiratory manifestations of xanthoma disseminatum, a rare histiocytosis syndrome characterized by disseminated lesions in a young male adult. Multimodality management of this disease, including the role of local radiotherapy, is discussed accompanied by a review of the literature.

Allogeneic bone marrow transplantation for children with histiocytic disorders: use of TBI and omission of etoposide in the conditioning regimen

The histiocytoses are rare disorders of antigen-processing phagocytic or antigen-presenting cells. Allogeneic bone marrow transplantation (BMT) can be curative of these disorders. We report a series of five children with Langerhans cell histiocytosis (n=2) or hemophagocytic lymphohistiocytosis (n=3), who received allogeneic BMT with a total body irradiation (TBI)-containing regimen (TBI, cytarabine, and cyclophosphamide) at our institution between 1995 and 2000. One of these patients received busulfan, cyclophosphamide, and etoposide for the first of two BMTs. All grafts except one (a matched sibling-donor graft) were T-cell-depleted grafts from unrelated donors. All received cyclosporine graft-versus-host disease (GvHD) prophylaxis; the recipient of the matched sibling graft also received methotrexate. Three patients engrafted at a median of 24 days after transplantation. The patient who did not receive TBI experienced primary graft failure and recurrent disease. After the TBI-containing conditioning regimen was given, a second transplant engrafted on day +17. One patient with concurrent myelodysplastic syndrome died of toxicity on day +33 without evidence of engraftment. No acute or chronic GvHD was observed. Four patients survive disease-free, a median of 63 months after transplantation, all with Lansky performance scores of 100. We conclude that a conditioning regimen containing TBI but not etoposide is effective in allogeneic BMT for children with histiocytic diseases.

Langerhans cell histiocytosis with orbital involvement

PURPOSE

To review three cases of Langerhans cell histiocytosis with orbital involvement that represent a significantly excessive incidence of this rare disease in one community. Current diagnostic criteria and therapeutic modalities related to Langerhans cell histiocytosis are reviewed.

METHODS

Case reports. We present clinical, radiologic, histopathologic, and epidemiologic information on three patients with Langerhans cell histiocytosis.

RESULTS

All three children, born within 18 months of one another, manifested rapidly progressive unilateral proptosis at age 2 years. By computed tomography, all had moderately enhancing lesions with involvement of the sphenoid bone and lateral orbit as well as the temporal lobe of the brain. All patients were treated with a combination of vincristine and prednisone, with variable resolution of their lesions. The occurrence of three cases in children born in Nogales, Arizona/ Mexico, suggests an incidence rate of 40 per million, which is approximately 26 times the expected rate (P = .0001).

CONCLUSIONS

The extraordinarily high incidence and the concentration of cases in both time and space of this cluster implies that Langerhans cell histiocytosis may be a sentinel disease for unusual environmental exposures.

Langerhans' cell histiocytosis (histiocytosis X): immunophenotype and growth fraction

The immunophenotype and proliferation fraction have been investigated in 26 cases of Langerhans' cell histiocytosis (LCH). In all cases LCH cells were positive for S-100 protein, CD1a, or both. In most cases LCH cells expressed the macrophage-associated marker CD68 and in two cases they contained lysozyme. Expression of both cytoplasmic CD2 and CD3 was observed in cryostat sections. An unexpected finding was the presence of placental alkaline phosphatase in LCH cells. Langerhans' cells in normal skin were negative for both CD2 and CD3, but a proportion contained placental alkaline phosphatase. In four cases of Rosai-Dorfman disease the histiocytic cells, which share certain immunophenotypic properties with Langerhans' cells, also were positive for placental alkaline phosphatase. A significant proportion of LCH cells stained positively with the antibody to proliferating cell nuclear antigen and also with the proliferation marker Ki-S1. A good correlation between the percentage of Ki-67-positive and proliferating cell nuclear antigen- and Ki-S1-positive cells, respectively, was observed. Thus, in comparison with their putative precursors, LCH cells have an aberrant phenotype and are proliferating locally. This might suggest that LCH is a neoplastic rather than a reactive process.

Precursor Langerhans cell histiocytosis. An unusual histiocytic proliferation in a patient with persistent non-Hodgkin lymphoma and terminal acute monocytic leukemia

BACKGROUND

Langerhans cell precursors are considered to be identical to their mature counterparts except for the lack of Birbeck granules. Proliferations composed of such histiocytes appear to be uncommon.

METHODS

Standard immunophenotypic, molecular genetic, and DNA content studies were used to characterize various hematopoietic disorders, including a proliferation of precursor Langerhans cells, which arose sequentially in a patient.

RESULTS

The patient studied initially had a low-grade, B-cell, non-Hodgkin lymphoma and subsequently had an unusual histiocytic proliferation (precursor Langerhans cell histiocytosis) in cutaneous and lymph node sites. The patient eventually died of acute myelogenous leukemia (FAB, M5).

CONCLUSIONS

A larger series is required to determine the significance of the precursor Langerhans cell phenotype, particularly with respect to the development of acute myelogenous leukemia.

Generalized papular xanthomatosis in mycosis fungoides

Xanthomas can occur in association with underlying lymphoproliferative disease, or they can result from lipid deposition in damaged or altered skin. We report a case of generalized papular xanthomas that developed in a patient with Sézary syndrome. The xanthomas were composed of foamy histiocytes that were shown by immunoperoxidase staining to be of the monocyte/macrophage lineage. Electron microscopic studies revealed lipid vacuoles, lysosomes, and myelin figures but no Birbeck granules, features that are consistent with a non-X histiocytosis. Generalized papular xanthomatosis has not been previously described in a patient with cutaneous T-cell lymphoma.

Immunohistochemistry and electron microscopy in Langerhans cell histiocytosis confined to the skin

Four cases of benign Langerhans cell histiocytosis limited to the skin were studied. In all three self-healing cases (cases 2, 3, and 4) many dense bodies, myelin bodies, and worm bodies were found. In one chronic case (case 1) none of these was identified. In all four cases, in addition to CD1, HLA-DR, and S-100 stains, interferon-gamma and S-100 beta-subunit were positive in the dermal tumor cells. Both interferon-gamma and S-100 beta-subunits were negative in the normal epidermal Langerhans cells. A comprehensive literature review yielded 87 cases of skin-limited Langerhans cell histiocytosis. These cases could be subgrouped into three categories: (1) those that resolved spontaneously, (2) those that responded to therapy and had no recurrence, and (3) those with persistent or recurrent lesions, not responding to therapy but still limited to the skin.

Eosinophilic granuloma of bone and biochemical demonstration of 49-kDa CD1a molecule expression by Langerhans-cell histiocytosis

Histiocytic cells infiltrating the lesions in eosinophilic granuloma of bone as well as in cutaneous histiocytosis X were studied using a murine monoclonal antibody (MA) produced with proliferating cells from an eosinophilic granuloma of bone. This MA reacts with Langerhans cells (LC) of normal human skin or mucous membranes and with proliferating cells of eosinophilic granuloma of bone and skin lesions of Letter-Siwe disease, as shown by immunohistochemistry and immunogold labelling. As other murine MA's obtained after immunization with human cortical thymocytes, this MA immunoprecipitates the 49-kDa CD1a antigen found on human LC and thymic-cell surfaces but not its breakdown product after treatment with trypsin, as demonstrated by analysis of immunoelectron labelling, cytofluorometry and gel electrophoresis. This first production of a CD1a MA from an eosinophilic granuloma supports the concept of Langerhans-cell histiocytosis.

The histiocytoses of childhood

The histiocytoses of childhood include Langerhans' cell histiocytosis, haemophagocytic syndrome (familial and reactive), sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease), juvenile xanthogranuloma and malignant histiocytosis. These disorders show wide variation in their clinical presentation, prognosis and genetic implications. All are characterized by localized or generalized proliferation of histiocytes, but they differ in their morphology, histochemical and immunochemical staining patterns and electronmicroscopical features. On the basis of a comprehensive clinical history and critical interpretation of morphology and immunocytochemistry using an appropriately selected panel of antibodies, a diagnosis can be reached in the majority of cases.

Human normal-resting epidermal Langerhans cells do express the type 3 complement receptor

The expression of CR3 by murine-resting epidermal Langerhans cells (LC) is well established, but CR3 expression by human normal-resting epidermal LC has not yet been demonstrated. In this study, highly sensitive immunostaining techniques, such as immunogold labelling in transmission- and scanning-electron microscopy, were used on freshly isolated, LC-enriched, normal human epidermal cells. Human normal resting epidermal LC were found to be CR3+, since a low but significant number of gold granules labelled the plasma membrane of all the LC observed under transmission-electron microscopy, and all the epidermal cells showing LC morphology as observed by scanning-electron microscopy.

Monoclonal antibody MT1: a marker for Langerhans cell histiocytosis

Langerhans cells and their pathologic counterparts can be identified in paraffin sections using immunohistochemical staining for S-100 protein. This procedure is useful in confirming a diagnosis of Langerhans cell histiocytosis (LCH). However, many other cell types are also positive for S-100 protein. Positive staining for CD1 (Leu 6) supports a diagnosis of LCH, but requires frozen tissue. A panel of antibodies would be desirable in confirming a diagnosis of LCH, particularly if these antibodies could be used on paraffin-embedded material. We studied the pattern of staining for commercially available monoclonal antibodies MT1, MT2, MB2, and LN1, which were originally marketed as lymphocyte markers, using paraffin-embedded tissue sections of cases of LCH. In all 20 cases pathologic Langerhans cells stained positively with MT1 only. Various other S-100 protein-positive lesions were also examined with MT1 and were consistently negative for MT1. Other cutaneous histiocytic and mast cell lesions were positive with MT1, but S-100 protein negative. Our results demonstrate that the monoclonal antibody MT1 serves as an additional marker for LCH and, together with S-100 protein, would make up a diagnostic panel of antibodies for LCH to be used on routine paraffin-embedded sections.

Adhesion molecules on the plasma membrane of epidermal cells. I. Human resting Langerhans cells express two members of the adherence-promoting CD11/CD18 family, namely, H-Mac-1 (CD11b/CD18) and gp 150,95 (CD11c/CD18)

The CD11/CD18 family of leukocyte adhesion-promoting proteins is comprised of three members, each composed of a shared beta subunit (CD18) noncovalently associated with unique alpha subunits (CD11a, CD11b and CD11c respectively). Such three heterodimers, named LFA-1 (CD11a/CD18), H-Mac-1 (CD11b/CD18) and gp150,95 (CD11c/CD18), are involved in mediating leukocyte adhesion in virtually all phases of the immune responses. Since Langerhans cells are regarded as cutaneous leukocytes, we investigated the expression of the members of the CD11/CD18 family on Langerhans cells. A vast series of immunostaining procedures was carried out, using monoclonal antibodies anti-CD11a, -CD11b, -CD11c, and -CD18. Normal skin frozen sections and epidermal sheets were investigated by immunohistology and immunofluorescence; suspended freshly isolated epidermal cells were processed using immunogold techniques, performed in both transmission and scanning electron microscopy, including double labeling procedures and semiquantitative analysis of the labeled cells. The results demonstrated the expression on the membrane of Langerhans cells of the CD11b, CD11c and CD18 antigens, thus indicating that at least both the H-Mac-1 (CD11b/CD18) and the gp150,95 (CD11c/CD18) members of the CD11/CD18 family are detectable on the cell surface of human resting Langerhans cells. Since both such moieties serve as adhesion molecules in (a) cell-cell interactions and in (b) leukocyte migration and localization, the present results suggest that H-Mac-1 and gp150,95 might display a key role (a) in promoting interactions between Langerhans cells and other cells, and (b) in guiding the migration and localization of Langerhans cells.

Immunoenzyme techniques in dermatopathology

The advantages and disadvantages of the immunofluorescence and immunoperoxidase techniques and an introductory description of the major variations of the basic immunoperoxidase method are discussed. The ability to identify intermediate filaments, T and B lymphocyte cell markers, S-100 proteins, myelin basic protein, and carcinoembryonic antigen in tissue sections can assist the dermatopathologist in classifying undifferentiated or histologically similar-appearing tumors. A systematic approach to the diagnosis of a majority of these tumors with the use of immunoenzyme staining is provided.

DMC1: a monoclonal antibody produced from histiocytosis X cells which reacts with the native CD1a molecule of human epidermal Langerhans cells

Human epidermal Langerhans cells express two (CD1a and CD1c) of the three human thymic cell surface differentiation antigens (CD1a, CD1b, and CD1c). The first cluster of differentiation antigens (CD1) is defined by a group of monoclonal antibodies (MCA). All these MCA were obtained after immunization of mice or rats with human cortical thymocytes. OKT6 MCA (a CD1a MCA) was the first to be described as reactive with human epidermal Langerhans cells. We produced a murine MCA, called DMC1, after immunization with proliferating Langerhans cells of Eosinophilic Granuloma of the bone (Histiocytosis X). In tissues DMC1 MCA reacted with epidermal dendritic cells (Langerhans cells) in the skin and cortical thymocytes in the thymus as observed on indirect immunofluorescence. At the ultrastructural level, DMC1 MCA was specific for Birbeck granule-containing Langerhans cells and did not react with melanocyte and keratinocyte populations. The quantitative analysis of immunoelectron labeling and the cytofluorometric study showed that the intensity of labeling was inversely correlated with the concentration of trypsin used in the preparation of epidermal cell from skin samples. DMC1 MCA precipitated a protein with a relative mass of 49,000 (CD1a molecule) from lysates of iodinated epidermal Langerhans cells under reducing conditions. It recognized the original CD1a molecule (Mr 49,000) but not the membrane breakdown product of CD1a (Mr 27,000) brought about by trypsin.

Letterer-Siwe disease in adults

Histiocytosis X (HX) is a rare disorder of histiocytic proliferation characterized by a broad spectrum of clinicopathologic disease. An unusual case of Letterer-Siwe disease (LSD) or subacute disseminated HX in a 71-year-old woman is presented. The patient had a 3-year history of splenomegaly before skin lesions developed. She presented to our clinic at 1.5 years later and the diagnosis of HX was made by skin biopsy. Topical nitrogen mustard (NM) therapy resulted in complete clearing of cutaneous lesions. Her condition was stable over the next 10 months. However, she subsequently suffered a rapid and fatal dissemination of her disease. Systemic treatment with prednisone, vinblastine sulphate, and suppressin A (SA) (a calf thymus derived hormone preparation that specifically induces suppressor T-cells) was ineffective. Characteristic histopathologic, immunohistochemical, and electron microscopic findings of HX are illustrated. A review of the adult cases of LSD and treatment options for HX are presented and discussed.

Simultaneous colloidal gold immunoelectronmicroscopy labeling of CD1a, HLA-DR, and CD4 surface antigens of human epidermal Langerhans cells

The simultaneous demonstration of three surface antigens of Langerhans cells (LC) within LC-enriched fresh epidermal cell suspensions from normal human skin was achieved, by means of a triple immunogold (IG) staining, using commercially available monoclonal antibodies (moAb) and immunoreagents, in a simple pre-embedding immunoelectronmicroscopy (IEM) procedure. As a result, suspended LC were triple-stained as follows: gold particles of 40 nm revealed the CD1 a antigen; gold particles of 20 nm revealed the HLA-DR antigen; and gold particles of 5 nm revealed the CD4 antigen. All the observed epidermal Birbeck granule-bearing LC were triple IG stained, thus simultaneously expressing the three surface differentiation antigens, which are therefore different from but coexisting with each other. The present investigation assesses the constant simultaneous expression by Birbeck granules bearing LC of not only CD1a and HLA-DR antigens, but also CD4 antigen. The occurrence is therefore excluded of both CD1a-positive HLA-DR-negative LC subpopulation and CD4-negative LC subpopulation, presumably due to the different sensitivity of the various procedures performed. The hypothetical occurrence of CD4-positive, CD1a-, and/or HLA-DR-negative LC subpopulations is ruled out. This study reaffirms indeed the high specificity and sensitivity of the IG-IEM method for a precise detection of the cell surface antigens of LC, and states the suitability of the IG labeling even for accurate multiple IEM stainings of LC.

Antigenic phenotype of Langerhans cell histiocytosis: an immunohistochemical study demonstrating the value of LN-2, LN-3, and vimentin

In order to determine the antigenic phenotype of the proliferating cells in Langerhans cell histiocytosis (LCH), we studied 15 such examples by using formalin- and B5-fixed, paraffin-embedded tissues. We used a panel of antibodies that are known to react with lymphocyte- and histiocyte-associated antigens. These included LN-1, LN-2, and LN-3 monoclonal antibodies (MoAbs), MoAbs to leukocyte common antigen (LCA), Leu-M1 antigen, vimentin, and epithelial membrane antigen (EMA), as well as polyclonal antibodies to lysozyme and S100 protein. The antigens encountered most frequently in LCH cells were S100 protein (93% of cases), vimentin (86%), and those detected by LN-2 (80%) and LN-3 (82%). Lysozyme was detected focally in two cases and diffusely in one case. The LCH cells were negative for LN-1, LCA, Leu-M1, and EMA. There was only one specimen in which S100 protein was not demonstrated; in this case, LN-3, vimentin, and T6 on frozen section were positive. The phenotype of LCH cells is similar to that of Langerhans' cells and interdigitating histiocytes. Our results demonstrate the value of using a panel of antibodies, including anti-vimentin MoAb, LN-2, and LN-3 for the immunophenotypic diagnosis of LCH in addition to an antibody to S100 protein.

Xanthoma disseminatum: a rare condition with non-X, non-lipid cutaneous histiocytopathy

We describe a 35-year-old man with cutaneous, mucosal, pulmonary, and bone involvement of xanthoma disseminatum. The 7-year course of the disease and the results of light and electron microscopic and immunocytochemical examinations are presented.

Large-cell hematolymphoid neoplasms of uncertain lineage

In almost every large study attempting to characterize non-Hodgkin's lymphomas, there is a small subset of tumors for which the lineage remains poorly defined. The investigators studied a series of 20 hematolymphoid neoplasms that could not be clearly assigned to the B or T cell lineage by phenotypic criteria. Histologically, 12 cases had an appearance suggesting a histiocytic origin, seven cases resembled a pleomorphic immunoblastic lymphoma, and one had a sarcomatoid appearance. By immunologic studies, a variety of B cell, T cell, and monocyte/macrophage markers were expressed on the neoplasms, often with coexpression of markers for different lineages. Twelve cases expressed the Ki-1 antigen. In immunogenotyping studies of T cell receptor (TCR) and immunoglobulin genes, 13 cases showed clonal rearrangements of the beta or gamma TCR gene; one of these cases also had clonal rearrangements of a light chain immunoglobulin gene. Seven cases showed a germline configuration with all combinations of probes and enzymes used. We conclude that a small subset of hematolymphoid neoplasms shows a pattern of diverse immunologic marker expression that does not appear to reflect normal differentiation. However, a majority of these cases contain clonal TCR gene rearrangements, suggesting a frequent relationship to the T lineage.

Primary histiocytosis X of the parieto-occipital lobe

Immunohistochemical and ultrastructural evidence support the concept that histiocytosis X is the result of proliferation of pathological Langerhans' cells. Central nervous system involvement by histiocytosis X has been commonly described in multisystem disease and in association with lytic skull lesions. Unifocal brain involvement by histiocytosis X without concomitant osseous involvement is rare, with only 14 cases reported in the literature to date. Ten of these cases have involved the hypothalamus; the remaining four have involved the frontal lobe (two cases) and the temporal lobe (two cases). The fifth case of extrahypothalamic unifocal histiocytosis X, the first female case, and the first case with parieto-occipital lobe involvement, is reported. Pathology demonstrated infiltration of brain parenchyma by clusters of characteristic histiocytosis X cells with an admixture of morphologically related giant cells, eosinophils, and lymphocytes. Langerhans' granules were identified in the histiocytosis X cells by electron microscopy. Immunohistochemistry showed strong S-100 protein, HLA-DR, and T6 antigen positivity by the histiocytosis X cells. Therapy included complete surgical excision and postoperative radiation therapy for the incompletely excised lesion. Patients with unifocal extrahypothalamic histiocytosis X may have a better prognosis than patients with localized hypothalamic disease.

The phenotypic spectrum of histiocytosis X cells

Proliferating cells in histiocytosis X (histiocytosis X cells) share many structural and immunophenotypic features with Langerhans cells, leading to the assumption that histiocytosis X represents a proliferative disorder of Langerhans cells. Because, depending on their state of activation and/or differentiation, Langerhans cells exhibit a varying immunophenotype, we investigated whether histiocytosis X cells display a similar phenotypic heterogeneity and, if so, whether the heterogenous biological behavior of histiocytosis X is reflected by differences in the immunophenotype of the proliferating cells. In 21 patients suffering from different clinical manifestations of histiocytosis X, proliferating cells uniformly expressed class I and II alloantigens, T200, CD1, CD4, and S100 protein. In 12 of 21 cases, histiocytosis X cells additionally exhibited immunocytochemically detectable amounts of C3b and C3bi receptors and certain monocyte/macrophage antigens (CDw14, Ki-M1, Ki-M6). This immunophenotypic heterogeneity of histiocytosis X cells could not be correlated with clinical course, prognosis, and final outcome of the disease in a given patient. The capacity of histiocytosis X cells to immunophenotypically mimic various states of Langerhans cell activation and/or differentiation, however, underscores the concept of histiocytosis X as a proliferative disorder of Langerhans cell origin.

Interdigitating cell sarcoma. A morphologic, immunohistologic, and enzyme-histochemical study

A 58-year-old man presented with an unusual sarcoma of the cervical lymph node. The tumor also involved the mesenteric lymph node and jejunum. Tumor cells possessed intracytoplasmic S100 protein, Leu-3a (T4), and HLA-DR antigens. The neoplastic cells also showed membranous ATPase activity. LeuM1, T6, Leu1, Leu2a, B1, lysozyme, and immunoglobulin were not recognized. Their fine structure was similar to that of interdigitating cells. These data are consistent with derivation from lymph node interdigitating reticulum cell.

Congenital self-healing histiocytosis (Hashimoto-Pritzker). An ultrastructural and immunohistochemical study

Congenital self-healing histiocytosis (CSHH) is a rare primary histiocytic skin disorder. Only a few cases have been studied by ultrastructure and immunohistochemistry. Here we report a new case that was investigated using an electron microscope and a panel of monoclonal (MCA) and polyclonal (PCA) antibodies. CSHH cells were found to bear the immunohistochemical phenotype of normal epidermal Langerhans cells (LC) and histiocytosis X (HX) cells (CD1a/c+, CD1b-, CD4+/-, human leukocyte antigen [HLA]-DR/DQ+, S-100+). However, an electron microscope showed a paucity of Birbeck granule (BG)-containing cells. This contrasted with their immunophenotype. This finding, along with other ultrastructural characteristics of CSHH cells, suggests that histologic differences exist between CSHH and HX. However, because no absolute histologic criterion is known that allows unequivocally the differential diagnosis between the two diseases, this distinction currently has to rely on clinical criteria, mainly the regressive course observed within a few months in CSHH. The precise nosologic position of CSHH among other histiocytic syndromes remains unsettled.

Letterer-Siwe disease: immunohistochemical evidence for a proliferative disorder involving immature cells of Langerhans lineage

The morphological, ultrastructural and immunophenotypic properties of Histiocytosis-X (H-X) cells were investigated in a lymph node involved by Letterer-Siwe (L-S) disease. H-X cells were T6+ (CD1a), S-100+, T4+ (CD4) and HLA-DR+; in addition they were consistently T11+ (CD2) and were stained by antibodies directed against receptors for transferrin (T9), C3bi (OKM-1/CD11b), IgG-Fc (Leu-11/CD16) and Interleukin-2 (IL-2R/CD25). On immunostained cytosmears, T6+ cells were highly polymorphic and a prominent fraction (45%) showed immature morphology, characterized by lymphoid appearance. Cells expressing macrophage markers (ANAE, AACT, Leu-M3/CD14, PAM-1) were 10-fold fewer than T6+ cells and did not show a lymphoid morphology. At TEM level, H-X cells were characterized by poor content of LC granules and by the presence of myelin-like laminated bodies and of lysosome-like dense bodies. The immunophenotypic properties of H-X cells were compared to those of epidermal Langerhans cells (LCs) and of LCs present in lymph nodes of three cases of dermatophatic lymphadenitis. Epidermal LCs were T6+/HLA-DR+, and sometimes faintly T4+. Lymph node LCs were T6+, S-100+, T4+, HLA-DR+, and showed the same variety of surface receptors detected in H-X cells; furthermore, in a case with massive infiltration of the paracortex by T6+ cells, lymph node LCs were faintly T11+ and some of the T6+ cells had lymphoid aspect. Our findings suggest that the H-X cell population of L-S disease is not homogeneous, but is composed of discrete cell subsets with distinctive antigenic and morphological traits closely resembling those of cells of LC lineage at different maturational stages.

Langerhans cell histiocytosis: an unusual case illustrating the value of immunohistochemistry in diagnosis

The morphological features of Langerhans cell histiocytosis (histiocytosis X) are characteristic but the diagnosis can on occasion be difficult. A case is presented that illustrates the diagnostic value of immunohistochemistry in the differential diagnosis of this condition. The cells of Langerhans cell histiocytosis were found to express CD1, CD4, CD11b and CD11c. They also reacted with EBM11, UCHM1, KB61 and HLA-DR. Occasional cells showed nuclear staining with Ki67, but no other lymphoid antigens were detected. Immunoreactivity of the cells of Langerhans cell histiocytosis with antibodies that recognize antigens present on macrophages provides further evidence for immunological similarities between these cell types.

Sinus histiocytosis clinically limited to the skin

Sinus histiocytosis with massive lymphadenopathy is a rare clinicopathologic entity that affects mainly children and young adults. Although the lymph nodes are the most common sites of involvement, extranodal infiltrates may arise in the orbits, skin, upper respiratory tract, and bone, as well as other organs. Approximately 10% of patients have had cutaneous infiltrates, but very few of them have had lesions limited to the skin. We treated a 15-year-old female with cutaneous nodules as the sole manifestation of the disease.

Epidermal Langerhans cell density in patients with pulmonary malignancies and chronic obstructive pulmonary disease

To evaluate the relationship between ELC density and pulmonary malignancies, as reported in previous investigations, we examined the nonsun-exposed epidermis of 18 patients with pulmonary cancer (CA) not receiving immunosuppressive therapy, 20 patients with chronic obstructive pulmonary disease (COPD-S), and 10 patients with COPD receiving glucocorticosteroid (GCS) therapy (COPD + S). The ELC density was not significantly different between lung tumor patients (1024 +/- 167) and COPD-S (1072 +/- 200, p less than 0.4) control patients, and we found no significant correlation between ELC density and tumor cell type, presence or absence of metastases, tumor stage, or present smoking status. Although we did detect that systemic GCS therapy significantly reduced the ELC density in COPD + S patients (910 +/- 211, p less than 0.05); use of inhaled or chronic low dose (less than or equal to 20 mg daily) GCS did not appear to significantly alter ELC density. In addition, anergy to epicutaneous dinitrochlorobenzene in CA and COPD + S patients positively correlated with a reduction in ELC density, suggesting a possible functional deficit arising from the numerical change. Further investigation is needed to elucidate whether factor(s) other than a reduction in ELC density are involved in the anergic state.

Human epidermal Langerhans cells internalize by receptor-mediated endocytosis T6 (CD1 "NA1/34") surface antigen. Birbeck granules are involved in the intracellular traffic of the T6 antigen

Using immunogold staining of a suspension of living human epidermal cells to identify the Langerhans cell membrane-associated antigen T6 (revealed by the monoclonal antibody BL6), we have observed internalization of T6 antigen in Langerhans cells. This phenomenon is at least partly due to receptor-mediated endocytosis involving coated pits, coated vesicles, endosomes, the smooth endoplasmic reticulum, and lysosomes. These ultrastructural results suggest that T6 antigen may be part of a receptor site. Following receptor-mediated endocytosis, the appearance in the cell center of the first labeled Birbeck granules suggests that Birbeck granules could represent T6 intracellular transport organelles carrying T6 from the central part of the cell to an unknown destination.

Immunohistochemical and ultrastructural studies on histiocytosis in children

Thirty-four cases of eosinophilic granulomas, 18 cases of diffuse histiocytosis-X, 2 cases of Letterer-Siwe-like syndrome with immunodeficiency, 4 cases of malignant histiocytosis and virus associated hemophagocytic syndrome were studied. On paraffin section, S100 protein, lysozyme, alpha-1-anti-trypsin, alpha-1-antichymotrypsin, alpha-2-macroglobulin, Transferrin, Ferritin, peanuts agglutinin, Concanavalin-A, and dolichos biflorus associated antigen were stained by the immunoperoxidase method. In a few fresh materials, T-cell subpopulation by use of monoclonal antibodies (OKT-3, 4, 6, and OK-M1) was examined by the immunoperoxidase method. Two types of Langerhans' cells were found, one is positive for Ferritin and alpha-2-macroglobulin in diffuse histiocytosis-X cells, and another is negative for them in both eosinophilic granulomas. Diffuse histiocytosis-X cell resembled the transformed type of Langerhans cell more than eosinophilic granuloma cells in cellular differentiation. It seemed that the term prolangerhans' cell proliferation disorder might be responsible for it.

Histiocytosis X: report of an oral soft tissue lesion without bony involvement

The case of a 65-year-old white man with painful oral soft tissue granulomatous lesions of histiocytosis X is reported. The clinical course and diagnostic and therapeutic measures are described. The manifestation of symptomatic oral soft lesions with no definable lesions of bone and the age of the patient are not consistent with the usual presentation of this disease, and thus emphasize its clinical variability. The rationale for the therapeutic regimen and the prognosis are reviewed.

Characterization of cytoplasmic lysozyme immunoreactivity as a histiocytic marker in normal canine tissues

The immunoreactive lysozyme distribution in normal canine tissues was determined to assess the value of lysozyme as a marker of histiocytic differentiation. Lysozyme was largely confined to monocytes, neutrophils, macrophages, serous cells in mucosal associated exocrine glands, and renal proximal tubular epithelium. Macrophages in the majority of tissues stained intensely for lysozyme, although in lymphoid tissues not all acid phosphatase and nonspecific esterase positive cells contained lysozyme. In particular, dendritic antigen presenting cells, including Langerhans cells, follicular dendritic cells, and interdigitating reticulum cells, lacked immunoreactive lysozyme; hence lysozyme appeared to represent a discriminatory marker with respect to these cells. Also, a small proportion of non-dendritic macrophages appeared to lack lysozyme. It was concluded that the demonstration of immunoreactive lysozyme was a useful adjunct to conventional morphological techniques for the identification of tissue macrophages provided that due caution was exercised in the interpretation of the results of lysozyme staining.

Utilization of cytoplasmic lysozyme immunoreactivity as a histiocytic marker in canine histiocytic disorders

Immunoreactive lysozyme was readily detectable in canine histiocytic disorders including systemic histiocytosis, malignant histiocytosis and granulomatous panniculitis. Lysozyme was less reliable as a histiocytic marker in cutaneous histiocytoma; forty percent of these tumors were negative for lysozyme expression. The marked heterogeneity in lysozyme expression in cutaneous histiocytoma may indicate that a proportion of these tumors show relatively primitive histiocytic differentiation and do not express lysozyme. Alternatively, this same proportion may exhibit a phenotype akin to cutaneous Langerhans cells which do not contain lysozyme. Lysozyme was not detectable in the tumor cells in lymphomatoid granulomatosis, atypical cutaneous histiocytoma, and histiocytic lymphosarcoma. Other evidence that these three disorders do not represent true histiocytic proliferative disorders is discussed.

The effect of phototherapies on cutaneous lesions of histiocytosis X in the elderly

The effect of therapeutic ultraviolet light (UV) radiation on the skin lesions of histiocytosis X (HX) was studied in two old patients. Histiocytosis X cells in the biopsy specimens were strongly reactive with OKT-6, OK-Ia1, an anti-S-100 protein antibody, and were weakly stained with Leu-3a. Some HX cells outgrown from the explants bore immunoglobulin G receptors (Fc-IgG) and C3 receptors. In accordance with clinical improvement after repeated topical 8-methoxypsolaren (8-MOP) plus UV-A (PUVA) or UV-B radiation, the density of infiltrating HX cells gradually was decreased. The PUVA therapy seemed to be more effective than UV-B radiation in our treatment schedule. Even after repeated phototherapies, however, the reactivity of surface and cytoplasmic antigens related to OKT-6, OK-Ia1, and S-100 protein in the remaining HX cells were the same as in untreated HX cells. Although the exact mechanism remains obscure, satisfactory therapeutic results were obtained in response to the phototherapies. New skin lesions eventually recurred after cessation of the treatments, but such eruptions resolved when additional PUVA was resumed. These studies confirm that HX cells share a battery of cytologic characteristics with epidermal Langerhans' cells (LC) and that repeated phototherapies provide a beneficial effect for skin lesions of HX without adverse reactions.