Interdigitating Reticulum Cells Research Articles

Concomitant Langerhans and Interdigitating Reticulum Cell Hyperplasia in a Reactive Lymph Node of an Infant with Omenn Syndrome: A Diagnostic Pitfall for Langerhans Cell Histiocytosis.

Omenn syndrome, a rare form of combined immunodeficiency in infants, presenting with recurrent infections, erythroderma, lymphadenopathy, hepatosplenomegaly, eosinophilia, and increased serum IgE levels. It is a fatal condition unless treated by hematopoietic stem cell transplant. Hence, an early diagnosis and a prompt treatment can lead to better outcome in these unfortunate babies afflicted with Omenn syndrome. Here, we present an 8-week-old infant with typical features of Omenn syndrome, both clinically as well as on laboratory analysis, but surprising immunohistochemical findings on lymph node biopsy.

P183 Histiocytic sarcoma of interdigitating reticular cells in the mediastinum - case report

Reticular dendritic cells are present in the germinal center of lymph nodes, with the function of pathogens phagocytation. They present antigens to B and T lymphocytes, acting, among other fronts, in the cellular memory. Histiocytic sarcoma is a rare malignant neoplasm with proliferation of cells with morphological and immunophenotypic characteristics of mature histiocytes derived from dendritic cells. In the mediastinum, histiocytic sarcoma of interdigitating reticular cells (HSIRC) are even more infrequent, with only 2 reports in the literature. Its histological diagnosis is considered a challenge, since it must be differentiated from other causes of mediastinal neoplasms, such as lymphomas, germinal tumors, and even lymph node metastases from carcinoma. The report is about a male patient, 69 years old, in schedule of radical prostatectomy due to a prostate adenocarcinoma. In his oncologic staging, he underwent chest tomography that demonstrated a mediastinal tumor suggestive of lymph node enlargement in the right paratracheal chain, of 2.8 cm. The patient was submitted to resection, which showed, in histological analysis, a highly pigmented, slightly differentiated fusiform neoplasm and bands of fibrous tissue, without necrosis and with slight atypia. The immunohistochemical panel showed no specific markers of epithelial, vascular, myogenic, neural or melanocytic histogenesis; In addition, CD21 and CD23 were negative, and CD68 positive. Thus, a diagnosis of HSIRC was made. Surgical resection was the only therapeutic modality performed, currently it is under ambulatory follow-up, with no signs of recurrence. HSIRC is mainly found in lymph nodes, as a localized disease or in disseminated form. It is extremely rare in mediastinal localization. The greatest difficulty reported in this type of sarcoma is its differential diagnosis. Most patients are asymptomatic or have nonspecific symptoms, and imaging is the main diagnostic tool. Current treatment protocols suggest optimal treatment as surgery alone, without radiotherapy or chemotherapy. However, a few studies described in the literature are not enough to guide unequivocally the treatment of these neoplasms. The patient is being followed up in the outpatient clinic for about 6 months after surgery, with no signs of recurrence. In conclusion, this is an extremely rare disease, poorly described in the literature, and should be included among the differential diagnoses of mediastinal lesions.

Can SOX-10 or KBA.62 Replace S100 Protein in Immunohistochemical Evaluation of Sentinel Lymph Nodes for Metastatic Melanoma?

Microscopic evaluation of sentinel lymph nodes for metastatic melanoma relies, in part, on the use of immunohistochemical analysis to identify minute metastatic deposits that may be overlooked on routine microscopy. At present S100 protein is widely used in this role, in large part for its superior sensitivity; however, interpretation is hampered by the presence of benign S100 protein-positive cellular elements present in every lymph node, leading to reduced specificity and consequent difficulties in interpretation. In recent years, multiple melanocytic markers have emerged that promise superior sensitivity and specificity, including KBA.62 and SOX-10. SOX-10 shows a nuclear pattern of staining. In normal tissue it is expressed in Schwann cells, melanocytes, and myoepithelial cells of salivary, bronchial, and mammary glands. KBA.62 is also specific except for staining of endothelial cells and shows a membranous staining pattern. This study was undertaken to determine whether KBA.62 or SOX-10 could equal (or surpass) the sensitivity of S100 protein while offering superior specificity in the immunohistochemical evaluation of sentinel lymph nodes for metastatic melanoma. In this study we performed immunohistochemical stains for S100 protein, Sox-10, and KBA.62 on 50 lymph nodes with proven metastatic melanoma. SOX-10 detected all cases of metastatic melanoma (50 of 50 cases; 100%) compared with S100 protein (48 of 50 cases; 96%) and KBA.62 (37 of 50 cases; 74%). There was no "background" staining of normal cellular elements with SOX-10 or KBA.62. In contrast, S100 protein was expressed in scattered dendritic interdigitating reticulum cells in the paracortex of lymph nodes, showing cytoplasmic and nuclear positivity, sometimes posing significant difficulty in differentiating benign reticulum cells from single cell metastatic melanoma. Our findings suggest that SOX-10 may be superior to S100 protein for identifying metastatic melanoma in a lymph node. KBA.62 was less sensitive than either marker, although more specific than S100 protein.

Immunophenotypic analysis of histiocytes involved in AIDS-associated Mycobacterium scrofulaceum infection: similarities with lepromatous lepra

The present study reports a rare case of systemic M. scrofulaceum infection in an AIDS patient and analyses the inflammatory infiltrate in a lymph node by immunohistochemistry. Special emphasis is put on the histiocytes. The diffuse infiltrate consists mainly of large histiocytes that contain numerous bacilli. These cells display the phenotype of mature histiocytes and in addition coexpress the antigens recognized by RFD7 and RFD9, both markers of different subsets of histiocytes which have been reported to be co-expressed by the infected histiocytes in the infiltrate of lepromatous lepra. Interdigitating reticulum cells are rare as well as T cells which are mainly of the suppressor/cytotoxic type. These findings are similar to those reported for lepromatous lepra and might indicate common deficiencies in T cell-macrophage interactions in both conditions. Superimposed on the diffuse infiltrate of large histiocytes we observed 'monocytic granulomas', the presence of which might be related to a reactional state comparable to erythema nodosum leprosum, a reactional state of lepromatous lepra.

Antigen-presenting cells in human cutaneous leishmaniasis due to Leishmania major.

In this study biopsies from skin lesions and draining lymph nodes of patients suffering from cutaneous leishmaniasis caused by Leishmania major were examined by immunohistochemistry, and by light and electron microscopy to identify the types of antigen-presenting cells (APC) and their location. APC, identified morphologically and by their expression of specific cell markers, included Langerhans cells, macrophages, follicular dendritic cells, and interdigitating reticulum cells of the paracortex of lymph nodes. These cells expressed MHC class II antigens and contained Leishmania antigen. Since some keratinocytes and endothelial cells also showed these characteristics, they may also act as APC. By examining tissue samples from skin lesions and draining lymph nodes it was possible to follow the probable route of trafficking of various inflammatory cells between the skin lesion and lymph nodes. Leishmania antigen containing Langerhans cells were found in the epidermis, dermis and the regional lymph nodes. We believe these cells translocate from the epidermis to the dermis, where they take up antigen and migrate to the paracortex of the regional lymph nodes. There they are intimately associated with cells of the paracortex, and could be involved in the generation of Leishmania-specific T memory cells. LFA-1-positive T cells of the CD45RO phenotype were found in the skin lesion. Venular endothelium in the skin lesions expressed intercellular adhesion molecule-1 (ICAM-1), which is the ligand for LFA-1. The migration of lymphocytes from the vascular lumen to the site of inflammation is possibly a result of the interaction of these two adhesion molecules.

Index of Suspicion in the Nursery

Index of Suspicion in the Nursery

Interdigitating Dendritic Cell Sarcoma of Cervical Lymph Nodes

Interdigitating dendritic cell sarcoma (IDCS) is a malignant neoplasm that arises from the interdigitating reticular cells of the lymph node. Dendritic cells are a heterogeneous group of antigen-presenting cells that play a major role in innate and adaptive immune responses. Subtypes of dendritic cells include Langerhans cells, interdigitating dendritic cells, follicular dendritic cells, and dermal dendrocytes. 1 Interdigitating dendritic cells reside in the T-cell areas of peripheral lymphoid tissue, including the paracortex of lymph node and tonsil, the splenic peri-arteriolar lymphoid sheaths, and the interfollicular areas of mucosa-associated lymphoid tissue, and are responsible for major histocompatibility complex-restricted stimulation of resting T cells. Interdigitating dendritic cell sarcoma is rare; to our knowledge, only 34 cases have been reported to date. 1-4 Lymphadenopathy is the most common physical finding at presentation, and 42% of cases occur in the head and neck. 1,2,4 Otolaryngologists evaluating a head and neck mass should therefore include IDCS in the differential diagnosis.

Primary mediastinal lymph node malignancy with features suggestive of dendritic cell sarcoma

A 56-year-old man underwent preoperative chest computed tomography to further evaluate a well defined mass in the middle lobe with subcarinal lymph node swelling. There was no pathological diagnosis established by either bronchoscopic biopsy specimens or computed tomography-guided percutaneous needle biopsy. The middle lobe and mediastinal lymph nodes were excised, then postoperative radiotherapy (60 Gy) was administered to the mediastinum. Results of histological and immunohistochemical study showed that the lung mass consisted of completely necrotic tissue and that the subcarinal lymph node was involved by malignant cells suggestive of dendritic cell sarcoma. Primary dendritic cell sarcoma of the mediastinal lymph node is extremely rare. Dendritic cell sarcoma is a neoplasm of reticular dendritic origin and includes both follicular dendritic cell sarcoma and interdigitating reticulum (or dendritic) cell sarcoma. These rare neoplasms may pose difficulty in pathologic diagnosis and treatment. Although our patient died of hepatic rupture due to dendritic cell sarcoma or gastric cancer metastases one year after surgery, complete surgical resection with or without postoperative radiotherapy may be an acceptable therapeutic option for localized dendritic cell sarcoma.

Morphological and immunohistochemical study of Down syndrome thymus

The incidence and severity of various histologic changes were studied in the thymuses from 35 Down syndrome (DS) patients. Variable histologic alterations up to fibrotic involution of the gland were found. In addition, immunohistochemical investigation showed a reduction or absence of interdigitating reticulum cells roughly correlated with the severity of morphologic changes. The complex architectural and cellular thymic alterations, concerning both cortical and medullary microenvironment, could be correlated with the imbalances of immunity in DS patients.

Distribution and Immunophenotype of DC-SIGN-Expressing Cells in SIV-Infected and Uninfected Macaques

DC-SIGN (dendritic cell-specific ICAM-3 grabbing nonintegrin), an external C-type lectin expressed on dendritic cells (DCs), has been proposed to play a pivotal role in trafficking HIV/SIV from mucosal surfaces to lymphoid tissues. Although the location of DC-SIGN expression has been established in a limited number of human tissues, its distribution in the rhesus macaque has not yet been determined. This study characterized the distribution and immunophenotype of DC-SIGN-expressing cells in SIV-infected and uninfected macaque tissues by immunohistochemistry (IHC) and confocal microscopy. IHC, using monoclonal and polyclonal antibodies against DC-SIGN, was performed on a variety of tissues. To further define the immunophenotype of DC-SIGN(+) cells, double-labeling with antibodies to CD68, fascin, and HLA-DR was done. In both infected and uninfected macaques, DC-SIGN(+) cells were located within the submucosa and lamina propria of tongue, vagina, rectum, and tonsil; however, no positive cells were present within the epithelium of any tissue. Antibodies to DC-SIGN also labeled Kupffer cells within the liver and scattered perivascular cells in the brain. Within lymph nodes, numerous positive cells were present within sinusoids in addition to cells consistent with interdigitating reticular cells in the paracortex and scattered follicular dendritic cells within germinal centers. In spleen of uninfected macaques, there was a similar distribution of DC-SIGN(+) cells with sinusoidal, marginal zone, and interdigitating dendritic cells staining; however, there was a marked paucity of staining in the spleens of SIV-infected macaques. DC-SIGN(+) cells were consistently CD68(+), but fascin(-) and HLA-DR(-). The absence of intraepithelial DC-SIGN-positive cells in mucosal tissues suggests that DC-SIGN does not play a significant role in transmucosal passage of HIV/SIV.

Die Sentinel-Lymphonodektomie aus histopathologischer Sicht

Histologischen Techniken kommt eine Schlüsselrolle für den Erfolg und für die Weiterentwicklung des Sentinel-Node-Gesamtkonzepts zu. Die im „Augsburg Consensus” international und interdisziplinär verabschiedeten Standards sind hierfür die Basis. Um Malignomzellen im Sentinel-Lymphknoten (SLK) auch in kleiner Zahl mit absoluter Spezifität und hinreichender Sensitivität identifizieren zu können, bedarf es der konventionellen histologischen (HE) und der immunhistochemischen (Markerwahl passend zum Immunphänotyp des Primärtumors) Untersuchung geeigneter Serien von Paraffinschnitten. Bei melanomassoziierten SLKs ist dabei besonders auf die Unterscheidung von ebenfalls S100-positiven kapsulären und trabekulären Nävuszellen, eingewanderten Langerhanszellen, interdigitierenden Retikulumzellen und intranodalen Nerven zu achten. Ein substanzielles Risiko melanompositiver SLKs und damit die Indikation zur SLNE besteht für Patienten mit Primärmelanomen ab einer Tumordicke von 0,76 mm nach Breslow. Die mikromorphometrische S-Klassifikation des SLK-Melanombefalls ist - auch in einer vereinfachten Version analog der Breslowschen Messmethode - ein erstrangiger Prognostikator sowohl für das Risiko noch nachgeschalteter Lymphknotenmetastasen in der jeweiligen Region als auch für die Manifestationswahrscheinlichkeit von Fernmetastasen und damit für das Gesamtüberleben. Ebenso wie die Breslow-assoziierte T-Klassifikation des Primärmelanoms ist die S-Klassifikation somit ein essenzielles Selektions- und Stratifikationskriterium für die Planung und Durchführung prospektiv randomisierter adjuvanter Therapiestudien beim malignen Melanom. Bisher verfügbare RT-PCR-Techniken eignen sich wegen unzureichender Spezifität für Melanomzellen nicht als diagnostische Alternativen zur Histologie und Immunhistochemie. Eine sinnvolle Kombination von HE-Histologie, Immunhistochemie und RT-PCR-Analysen ohne Gefährdung bereits erreichter diagnostischer Standards gelingt durch Verwendung unmittelbar aufeinanderfolgender Paraffinschnitte. Auf diese Weise lässt sich die Sensitivität für die Identifikation von Melanom- und mehr noch von Nävuszellen in SLKs ohne Spezifitätseinbuße weiter verbessern.

Follicular dendritic cell sarcoma and interdigitating reticulum cell sarcoma: a review.

Neoplasms of reticular dendritic origin are extremely rare and include the follicular dendritic cell sarcoma (FDCS) and the interdigitating reticulum (or dendritic) cell sarcoma (IDCS). In this article, we review the literature pertaining to the two diseases and describe clinical observations and salient pathologic features, including information provided by authors of FDCS and IDDCS reports. We performed a computerized database search for published articles regarding FDCS and IDDCS. The articles were evaluated critically by the authors. Simple descriptive statistics were used to analyze the data. There are 51 cases of FDCS and 21 cases of IDDCS that are well documented in the literature. The pathologic diagnosis of FDCS and IDDCS is often challenging and requires morphologic, immunophenotypic, cytochemical, and electron-microscopic analysis. Patients with FDCS usually present with cervical or axillary lymphadenopathy, but extranodal disease has been described. In at least some patients, preexisting Castleman's disease has been recognized. Resected localized disease may be prevented from recurrence by consolidative radiotherapy. Chemotherapy regimens have shown nondurable antitumor activity in FDCS. Patients with IDDCS usually present with lymphadenopathy. The clinical course of IDDCS has been variable, but it seems to be more aggressive than that of FDCS. Variable degrees of remission may be achieved with chemotherapy. FDCS and IDDCS are rare neoplasms that may pose difficulty in pathologic diagnosis. IDDCS seems to display a more aggressive behavior than FDCS. Patients with IDDCS and FDCS can eventually die of disease progression. The role of chemotherapy and radiotherapy is not clearly defined.

Follicular dendritic cell sarcoma and interdigitating reticulum cell sarcoma: A review

Neoplasms of reticular dendritic origin are extremely rare and include the follicular dendritic cell sarcoma (FDCS) and the interdigitating reticulum (or dendritic) cell sarcoma (IDCS). In this article, we review the literature pertaining to the two diseases and describe clinical observations and salient pathologic features, including information provided by authors of FDCS and IDDCS reports. We performed a computerized database search for published articles regarding FDCS and IDDCS. The articles were evaluated critically by the authors. Simple descriptive statistics were used to analyze the data. There are 51 cases of FDCS and 21 cases of IDDCS that are well documented in the literature. The pathologic diagnosis of FDCS and IDDCS is often challenging and requires morphologic, immunophenotypic, cytochemical, and electron-microscopic analysis. Patients with FDCS usually present with cervical or axillary lymphadenopathy, but extranodal disease has been described. In at least some patients, preexisting Castleman's disease has been recognized. Resected localized disease may be prevented from recurrence by consolidative radiotherapy. Chemotherapy regimens have shown nondurable antitumor activity in FDCS. Patients with IDDCS usually present with lymphadenopathy. The clinical course of IDDCS has been variable, but it seems to be more aggressive than that of FDCS. Variable degrees of remission may be achieved with chemotherapy. FDCS and IDDCS are rare neoplasms that may pose difficulty in pathologic diagnosis. IDDCS seems to display a more aggressive behavior than FDCS. Patients with IDDCS and FDCS can eventually die of disease progression. The role of chemotherapy and radiotherapy is not clearly defined. Am. J. Hematol. 59:161–167, 1998. © 1998 Wiley-Liss, Inc.

Heterogeneity of Dendritic Cells in Human Superficial Lymph Node: In Vitro Maturation of Immature Dendritic Cells into Mature or Activated Interdigitating Reticulum Cells

A two-color immunofluorescent analysis indicated that dendritic cells (DCs) in the human axillar lymph nodes (ie, lymph nodal DCs (LnDCs)) can be classified into three subsets. The first subset consists of CD1a+/CD86(- or dim)/CD83(- or dim) nondendriform DCs found mainly in lymph sinuses, the second is of CD1a-/CD86+/CD83+ dendriform DCs scattered in normal T zones, and the third is of large CD1a(bright)/CD86+/CD83+ dendriform DCs occasionally found in hyperplastic T zones. A three-color flow cytometric analysis, immunoperoxidase staining, and electron microscopic observation indicated that the majority of LnDCs corresponded to the first subset, which showed distinctive characteristics of DCs but did not fulfill the ultrastructural criteria for interdigitating reticulum cells (IDCs) and did not contain Birbeck granules. When LnDCs were cultured for 7 days, they became large CD1a(dim)/CD86+/CD83+ dendriform cells, which formed large complexes with many T cells and exhibited distinctive ultrastructural features of interdigitating reticulum cells. LnDCs cultured in the presence of granulocyte/macrophage colony-stimulating factor became markedly larger CD1a(bright)/CD86+/CD83+ dendriform cells forming large complexes with numerous T cells. These findings suggest that cells of the first subset represent immature LnDCs just migrating from epidermis, those of the second subset represent interdigitating reticulum cells, and those of the third subset represent interdigitating reticulum cells probably stimulated with certain immunostimulatory cytokines such as granulocyte/macrophage colony-stimulating factor. It is also suggested that either the second or the third subsets of LnDCs are derived from the first subset.

Inflammatory infiltrate and interleukin-8 expression in the synovium of psoriatic arthritis--an immunohistochemical and mRNA analysis.

Psoriatic arthritis is an inflammatory arthropathy that ultimately can lead to joint destruction. In this study, we investigated the immunophenotypes of the inflammatory cells and the expression of interleukin-8 (IL-8), which is the hallmark chemoattractant cytokine of psoriasis in synovial membranes from patients exhibiting active psoriatic synovitis (n = 9). The tissue samples were examined by immunohistochemistry, Western blot analysis and in situ hybridisation. The inflammatory infiltrate consisted predominantly of CD3+ T lymphocytes, with a higher proportion of CD4+ than CD8+ T lymphocytes in six cases. CD3+ T lymphocytes were focally distributed near small blood vessels and the enlarged synovial intima. CD1+ interdigitating reticulum cells were not detected. CD22+ B lymphocytes and plasma cells were found in small aggregates without KiM4+ follicular dendritic cells. KiM8+ macrophages were located in the synovial intima and were distributed in a diffuse pattern near the synovial lining cells. CD15+ neutrophil granulocytes were detected in four cases. They were preferentially located in the vicinity of blood vessels and the synovial intima. IL-8 was found at a high level in the synovial lining cells and to a lesser extent in cells located in the perivascular areas. Immunofluorescence double staining showed IL-8 to be expressed in KiM8+ multinucleated giant cells, KiM8+ macrophages and CD3+ T lymphocytes. IL-8 receptor A was demonstrated in the synovial lining and in macrophages and lymphocytes. IL-8 was detected by immunoblot analysis of the synovial tissue at 8.4 kD. Employing in situ hybridisation, IL-8 mRNA was strongly and preferentially expressed in the synovial intima, as well as in macrophages and lymphocytes. The immunophenotype of the psoriatic arthritis inflammatory cells shows great similarity to the inflammatory infiltrate found in the synovial tissue of patients with rheumatoid arthritis. The preferential expression of IL-8 and IL-8 mRNA in the enlarged synovial intima and in lymphocytes and macrophages suggests that IL-8 exerts its action through activated mononuclear cells and T lymphocytes. It seems to play a role in regulating leucocyte traffic into the enlarged synovial intima and may contribute to the aggressive synovitis of patients with psoriatic arthritis.

Significance of Interdigitating Reticulum Cells in Omenn's Syndrome

Bahadoran, Philippe M.D.; Rieux-Laucat, Frédéric Ph.D; Canioni, Danielle M.D.; Le Deist, Françoise M.D.; Fischer, Alain M.D., Ph.D.; Brousse, Nicole M.D.

An immuno-electron-microscopic study of human thymic B cells.

Thymic B cells are a constituent of normal human thymic medulla. They are supposed to play a role in T cell maturation. Thymic B cells have been characterized morphologically and immunohistochemically at the light-microscopic level. Their ultrastructural appearance in vivo has not been demonstrated. Six normal infantile thymi were immunolabelled with the pan-B cell marker CD20 using a pre-embedding technique and viewed at the electron-microscopic level. Cells expressing CD20 had long cytoplasmic processes. They were all "asteroid" in shape and in close contact with thymocytes. Also, their long cytoplasmic processes intermingled with cytoplasmic processes of cells that were presumed to be interdigitating reticulum cells (IDC) based on morphological criteria. Thymic B cells may act in concert with IDC during T cell maturation.

MONOKINE EXPRESSION IN LANGERHANS' CELL HISTIOCYTOSIS AND SINUS HISTIOCYTOSIS WITH MASSIVE LYMPHADENOPATHY (ROSAI-DORFMAN DISEASE)

Langerhans' cell histiocytosis (LCH) is a clonal proliferation of Langerhans cells (LC) showing histologically an abundant reactive infiltrate composed of macrophages and lymphocytes, as well as eosinophilic and neutrophilic granulocytes. Rosai-Dorfman disease (RDD) shows a sinusoidal accumulation of large histiocytic cells with an immunophenotype similar to LC of LCH. The histological picture of LCH is reminiscent of an inflammatory disorder and LC may produce cytokines and are influenced by these soluble factors. This study set out to establish the monokine expression pattern in LCH in comparison with those of RDD; dermatopathic lymphadenopathy, which also shows a proliferation of S100-positive dendritic cells; and LC in normal skin specimens. Isotopic in situ hybridization was used for the detection of transcripts of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1 beta, in some cases combined with immunohistology for the S100 protein or CD68. In all 11 tissue samples from eight patients, LC of LCH expressed TNF-alpha; in two cases IL-1 beta transcripts were additionally noted in some LC, whereas IL-6 was found in reactive cells. Large histiocytic cells of RDD expressed all three monokines, whereas minimal or no expression of these cytokines could be detected in interdigitating reticulum cells in dermatopathic lymphadenopathy. In two out of five normal skin samples, only TNF-alpha specific signals were observed in LC. These data suggest that histologically different lesions of the histiocytic/dendritic cell system display distinct cytokine profiles. The expression of monokines, which have been demonstrated to influence various functions of epidermal LC, may play a role in the pathogenesis of LCH. Systemic symptoms in RDD may be related to enhanced production of monokines in these lesions.

MONOKINE EXPRESSION IN LANGERHANS' CELL HISTIOCYTOSIS AND SINUS HISTIOCYTOSIS WITH MASSIVE LYMPHADENOPATHY (ROSAI–DORFMAN DISEASE)

Langerhans' cell histiocytosis (LCH) is a clonal proliferation of Langerhans cells (LC) showing histologically an abundant reactive infiltrate composed of macrophages and lymphocytes, as well as eosinophilic and neutrophilic granulocytes. Rosai–Dorfman disease (RDD) shows a sinusoidal accumulation of large histiocytic cells with an immunophenotype similar to LC of LCH. The histological picture of LCH is reminiscent of an inflammatory disorder and LC may produce cytokines and are influenced by these soluble factors. This study set out to establish the monokine expression pattern in LCH in comparison with those of RDD; dermatopathic lymphadenopathy, which also shows a proliferation of S100-positive dendritic cells; and LC in normal skin specimens. Isotopic in situ hybridization was used for the detection of transcripts of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β, in some cases combined with immunohistology for the S100 protein or CD68. In all 11 tissue samples from eight patients, LC of LCH expressed TNF-α; in two cases IL-1β transcripts were additionally noted in some LC, whereas IL-6 was found in reactive cells. Large histiocytic cells of RDD expressed all three monokines, whereas minimal or no expression of these cytokines could be detected in interdigitating reticulum cells in dermatopathic lymphadenopathy. In two out of five normal skin samples, only TNF-α specific signals were observed in LC. These data suggest that histologically different lesions of the histiocytic/dendritic cell system display distinct cytokine profiles. The expression of monokines, which have been demonstrated to influence various functions of epidermal LC, may play a role in the pathogenesis of LCH. Systemic symptoms in RDD may be related to enhanced production of monokines in these lesions.

Cytogenetic findings in rare pediatric tumors: Report of a case of interdigitating reticulum cell sarcoma and a case of pancreatoblastoma

Cytogenetic findings in rare pediatric tumors: Report of a case of interdigitating reticulum cell sarcoma and a case of pancreatoblastoma