Langerhans cells: involvement in the pathogenesis of mycosis fungoides

Conjugal transformed mycosis fungoides: the unknown role of viral infection and environmental exposures in the development of cutaneous T-cell lymphoma

The etiology of mycosis fungoides (MF) is uncertain, although infectious agents and other environmental exposures have been implicated. We describe what appears to be the first case in which both a husband and his wife were diagnosed with large-cell transformation of MF. After 10 years of having stage I MF, the wife developed tumors that showed sheets of large transformed cells with dysplastic nuclei on skin biopsies, leading to a diagnosis of transformed MF. Her husband was diagnosed 14 months later with transformed MF following a biopsy of his right arm and leg after a 15-year history of presumed psoriasis. The fact that this rare occurrence happened in a couple who had been married for more than 25 years points to a common environmental exposure. Future studies should aim to clarify the potential role of infectious agents, such as human T-lymphotropic virus I and II, cytomegalovirus, Epstein-Barr virus, and other environmental exposures, in the development of MF.

Cutaneous T-cell lymphoma and atopy: is there an association?

BACKGROUND

Case reports have suggested a relationship between atopic diatheses and Sézary syndrome, pre-Sézary syndrome or mycosis fungoides. However, Sézary and pre-Sézary syndromes are rare entities, and this association has never been analysed in greater detail for specific subtypes of cutaneous T-cell lymphoma (CTCL).

OBJECTIVES

To evaluate the prevalence of atopy in subjects with Sézary syndrome, pre-Sézary syndrome or mycosis fungoides, and to compare the rates with the reported prevalence of atopy in the general population.

METHODS

We retrospectively reviewed the records of 157 patients with the diagnosis of Sézary or pre-Sézary syndrome seen between 1965 and 2000, and 102 patients with the diagnosis of mycosis fungoides evaluated from 1994 to 2000 at Mayo Clinic.

RESULTS

Of 157 subjects with Sézary or pre-Sézary syndrome and 102 subjects with mycosis fungoides, 18 and 12, respectively, were identified as having a history of atopic dermatitis, asthma or allergic rhinitis. The prevalence rates of atopy in Sézary or pre-Sézary syndrome and mycosis fungoides were 11.5% (95% confidence interval 6.9-17.5%) and 11.8% (6.2-19.7%), respectively.

CONCLUSIONS

No significant difference exists in the prevalence of atopy in Sézary or pre-Sézary syndrome compared with that in mycosis fungoides (chi2-test, P = 1.00). Furthermore, the rates of atopy in Sézary or pre-Sézary syndrome and mycosis fungoides are not significantly different from the prevalence of atopy in the general population (17-40%). On the basis of these observations, no evidence currently implicates a causal association of CTCL with atopy.

Examination of mycosis fungoides for the presence of Epstein-Barr virus and human herpesvirus-6 by polymerase chain reaction

BACKGROUND

The aetiology of cutaneous T-cell lymphoma (CTCL) remains unknown despite numerous investigations. In recent years, retroviruses and human herpesviruses have been implicated to play a causal part in CTCL.

OBJECTIVE

The aim of this study was to elucidate the possible aetiopathogenetic role of human herpesviruses (HHV) in mycosis fungoides (MF).

METHODS

Polymerase chain reaction was used to study formalin-fixed, paraffin-embedded lesional skin biopsies from 92 subjects with MF to evidence possible presence of Epstein-Barr virus (EBV) and HHV-6.

RESULTS

Biopsy specimens from nine subjects (9.8%) evidenced EBV DNA, whereas all except one of the subjects (1.1%) lacked HHV-6 DNA.

CONCLUSIONS

Although these findings do not support a primary aetiological role for EBV and HHV-6 in classical CTCL, the possibility remains that both viruses, particularly EBV, may act as potential cofactors in the development of CTCL.

Reduced number of CD1a+ cells in cutaneous B-cell lymphoma

Cutaneous B-cell lymphoma is difficult to distinguish from pseudolymphoma. The histologic pattern and monoclonal restriction (immunohistochemical analysis and molecular biology) are the criteria used for differentiating these entities. CD1a+ dendritic cells have been observed in the infiltrates of T-cell lymphoma, but the presence of these CD1a+ cells has not been compared in B-cell lymphoma and pseudolymphoma. We studied the presence of CD1a+ cells on frozen sections of 23 B-cell lymphomas, 13 pseudolymphomas, and 17 T-cell lymphomas by immunohistochemical analysis. We found abundant CD1a+ dendritic cells in only 1 (4%) of 23 B-cell lymphomas, whereas in 8 (62%) of 13 pseudolymphomas and 17 (100%) of 17 T-cell lymphomas, strong CD1a staining was present. Our study demonstrates a distinct pattern of CD1a staining in the infiltrates of B-cell lymphoma and pseudolymphoma that may be of value in the differential diagnosis of these skin disorders.

Are alcohol intake and smoking associated with mycosis fungoides? A European multicentre case-control study

The incidence of mycosis fungoides (MF) is low, and the aetiology of the disease is unknown. The aim of this study was to investigate whether wine consumption protects against the disease and whether smoking constitutes a risk factor. This paper is part of the European Rare Cancers Study that tries to determine the risk factors for seven selective rare cancers, including mycosis fungoides, involved in the development of cancer. A multicentre case-control study was conducted in six European countries. Only incident cases with confirmed histology were included in the analysis which include a total of 76 cases of MF and 2899 controls. Wine intake had no protective effect; on the contrary the consumption of more than 24 g of alcohol per day was associated with a high risk of MF (odds ratio (OR)=3.02, 95% confidence interval (CI), 1.34-6.79), after adjusting for centre, country, age, sex and education. There was a dose-dependent increase in the risk of MF with increased smoking habits, albeit the observed trend was not statistically significant. A combined exposure to high tobacco and alcohol use yielded a significantly increased risk factor for MF (P=0.0073). Alcohol intake was associated with MF.

Interaction of human immunodeficiency virus type 1, human T-cell leukemia/lymphoma virus type I (HTLV-I), and HTLV-II with in vitro-generated dendritic cells

Although it is known that impairment of dendritic cells (DC) plays a role in the pathogenesis and immunosuppression of retrovirus-associated diseases, it is not clear whether, or to what extent, these antigen-presenting cells themselves become infected. The realization that the cells can be generated in vitro in larger numbers than can be isolated from circulating blood or bone marrow raised the possibility that they could be used for therapeutic purposes. Therefore, we investigated whether DC generated in vitro from CD34 precursors are susceptible to infection when cocultured with human immunodeficiency virus type 1- or human T-cell leukemia/lymphoma virus-infected cell lines. While there appears to be a remarkable affinity of the viruses for the plasma membranes of the DC, interiorization or budding was not observed in 30 experiments carried out under a variety of conditions.

T-cell receptor variable region gene expression in cutaneous T-cell lymphomas

The cutaneous T-cell lymphomas (CTCL) are a group of diseases characterized by malignant proliferations of CD4 positive T-cells having monoclonally rearranged T-cell receptor (TCR) genes. A recent study using monoclonal antibodies to two TCR beta-chain variable (V) region gene products showed preferential expression of the V beta 8 gene product in these tumors. The finding of predominant usage of a single V beta gene would imply that selection by antigen is important in the etiology of these tumors. We have studied eight cases of cutaneous T-cell lymphoma and one cell line derived from a patient with mycosis fungoides/Sezary syndrome, using an extended panel of antibodies to V region gene products. Contrary to the previous report, in our study expression of the V beta 8 gene product by tumor cells was not observed in any of the cases of CTCL or in the tumor cell line studied; preferential use of any of the variable region genes recognized by the antibodies in the panel was not observed.

Possible role of Epstein-Barr virus infection in cutaneous T-cell lymphomas

Although cutaneous T-cell lymphoma (CTCL) is a neoplastic helper T-cell disorder of unknown etiology, prolonged antigenic stimulation has been postulated to contribute to the development of this disease. Because Epstein-Barr Virus (EBV) infection has been associated with several different lymphomas, the sera of 21 CTCL patients were examined for antibodies to EBV antigens. By using complement immunofluorescence (CIF) techniques, 13 of 21 CTCL patients had detectable antibodies to Epstein-Barr Nuclear Antigens (EBNA), whereas only five of 20 control psoriatic patients were CIF positive. When immunoblot analysis was employed, all 21 of the CTCL patients had antibodies to the EBV antigens, EBNA, whereas only 12 of the control patients had detectable antibodies to these antigens. In addition, three of 21 CTCL patients had antibodies to the EBV-associated antigen, rheumatoid arthritis nuclear antigen (RANA), as determined by double immunodiffusion, whereas none of the control sera contained anti-RANA antibodies. These results indicate that antibodies against EBV antigens are found with a higher frequency and concentration in patients with CTCL when compared to controls and suggest that EBV products might serve as a possible stimulus for the development of this malignant disease.

Epidermal Langerhans' cell densities influence survival in mycosis fungoides and Sézary syndrome

Because Langerhans' cells (LC) (CD1a-positive epidermal cells) have been discussed to be involved in the pathogenesis of mycosis fungoides and Sézary syndrome, the authors examined the influence of densities of Langerhans' cells and, concurrently, of other phenotypes retrospectively on survival of 35 patients. Cell densities were assessed on cryostat sections (alkaline phosphatase antialkaline phosphatase-technique) of the respective diagnostic biopsy specimens. Additionally, two clinical parameters (age, stage of disease) were evaluated. CD1a-positive epidermal cells were demonstrated to be the only cell population being significantly associated (P = 0.011) with survival. Death resulting from mycosis fungoides and Sézary syndrome was significantly (P = 0.003) less frequent in patients with epidermal CD1a-positive cell densities higher than 90 cells/mm2 (optimal break point) as compared with patients with lower numbers. These results suggest that Langerhans' cells have a significant impact on prognosis of patients with mycosis fungoides and Sézary syndrome. They play an important role in the host defense mechanisms against these lymphomas rather than to favor their progression as proposed recently.

Langerhans cells and mycosis fungoides--a critical overview of their pathogenic role in the disease

Skin biopsies from seven patients with mycosis fungoides in various clinical stages (patches, plaques, nodules) were studied immunohistochemically and ultrastructurally, with the aim of investigating and quantifying the distribution of Langerhans cells and their relationships to mycosis cells. Our findings have revealed that in patches and plaques both Langerhans cells and mycosis cells were numerous in the epidermis. Notwithstanding this, in all the specimens examined, only one Langerhans cell forming close contact with a mycosis cell was detected. In the nodules, Langerhans cells and mycosis cells were sparse in the epidermis and no contacts were seen between them. Moreover, in all the patients studied, only a single Langerhans cell was found in the dermal infiltrate without any closely related mycosis cells. Conversely, numerous interdigitating cells have been found in the dermis of patches and plaques, often tightly adhering to mycosis cells. In the nodule, a few scattered interdigitating cells were seen, but often these had close contacts with neoplastic lymphoid cells. These findings indicate that close apposition between Langerhans cells and mycosis cells, which led previous authors to hypothesize a persistent stimulatory action of Langerhans cells on T lymphocytes, eventually leading to the malignant transformation of the latter, is unusual in mycosis fungoides. Therefore, if such a pathogenic role may be attributed to accessory cells in mycosis fungoides it is more probably exerted by dermal interdigitating cells and not by Langerhans cells, as previously proposed.

Role of epidermal Langerhans cells in viral infections

Langerhans cells function as highly potent antigen-presenting cells in the epidermis. In the last few years, their role in viral infections has been studied in various experimental systems. They have been shown to be involved in the pathogenesis of a number of infections of viral origin. These include vaccinia virus, human papilloma virus, herpes simplex virus, foot and mouth disease virus and human retrovirus infections. Studies on the effect of various factors, that are known to modulate the activity and density of Langerhans cell in the epidermis, may lead in the future to the development of new strategies aimed at inhibiting virus infections or even eradicating latent infection.

Does radiation-induced abrogation of skin Langerhans cell functions lead to enhanced incidence of skin tumors in patients with genetic disorders of DNA repair?

A hypothesis is presented which states that persons with the genetic disorders xeroderma pigmentosum and ataxia-telangiectasia, manifested by a deficiency of DNA repair, develop cutaneous tumors due to the elimination of reticuloendothelial system cells (Langerhans cells) in the skin, and the subsequent loss of control of epidermal cellular elements.

Tumor stage mycosis fungoides in a patient treated with long-term corticosteroids for asthma and atopic-like dermatitis

An association between atopy and the Sézary syndrome has been recognized in some patients. Our case represents an association between adult-onset asthma and atopic-like dermatitis, markedly elevated IgE levels, and the development of tumor stage mycosis fungoides (MF) in a patient receiving long-term corticosteroid therapy. The chronic eczematous dermatitis may have represented evolving MF in which the specific diagnosis was delayed by treatment with topical and systemic corticosteroids until advanced tumor stage disease. This case, in conjunction with prior reports, suggests that an atopic diathesis can be associated with both leukemic and nonleukemic forms of cutaneous T-cell lymphoma.

Immunopathological and ultrastructural findings in human allergic and irritant contact dermatitis

The histopathological features of allergic contact dermatitis were compared with those of irritant contact dermatitis in a group of 17 subjects. Each patient received simultaneous patch tests of a known allergen and a standardized irritant (benzalkonium chloride). The cellular changes occurring between 3 h and 7 days after patch test application were studied by light and electron microscopy and immunocytochemistry. No differences were observed between the induced allergic contact dermatitis (ACD) and the irritant contact dermatitis (ICD), either in the responding cell types or the sequence of cellular events. Both reactions showed a predominantly T lymphocyte infiltrate with no polymorphonuclear leukocyte involvement. Apposition of Langerhans cells to lymphocytes in the epidermis was seen in both types of response. Considerable variability in the intensity of reaction to irritant and allergen occurred within individuals. There was no statistically significant difference between the intensity of the reactions to the irritant and the allergen.

A histologic study of lymph nodes from patients with the Sézary syndrome

Lymph node sections from 12 patients with Sézary syndrome (SS) were studied histologically. The histopathologic alterations were compared with those in lymph nodes from four patients with (erythrodermatic) mycosis fungoides (MF) and two patients with a benign form of erythroderma. Most SS lymph nodes showed a rather monotonous and diffuse infiltration of cerebriform mononuclear cells (CMC), which tended to efface the normal lymph node architecture. By contrast, in lymph nodes involved by MF there was not only an increase in the number of CMC, but also a marked increase in the number of interdigitating reticulum cells that often showed a considerable degree of nuclear polymorphia. In the advanced stages of lymph node involvement by MF, blastic transformation was much more pronounced than in the SS lymph nodes. These histologic differences between MF and SS lymph nodes suggest that different pathogenetic mechanisms may be operative in the development of either of these conditions.

Langerhans cells in verruciform xanthomas: an immunoperoxidase study of 10 oral cases

Ten oral verruciform xanthomas were studied using an immunoperoxidase stain for S-100 protein. All cases exhibited positively stained dendritic cells among the mononuclear inflammatory cell infiltrate at the base of the lesions and to a lesser extent among the "foam cells". The foam cells were, however, negative for S-100 staining. We suggest that, based on these findings, verruciform xanthomas belong to a new category of "non-X histiocytoses" in which the presence of Langerhans cells suggests an immunologic pathogenesis.

The lymph node in mycosis fungoides: a light and electron microscopy and immunohistological study supporting the Langerhans' cell-retrovirus hypothesis

This paper describes the light and electron microscopy and monoclonal antibody findings in the lymph nodes of nine patients with mycosis fungoides. Four cases showed dermatopathic change characterized by close association between small convoluted T4 lymphocytes and T6 antigen-presenting cells (Langerhans' and indeterminate dendritic cells) in the sinuses and paracortical zones. The T4:T8 ratio was between 3 and 5:1. One case showed dermatopathic change but included large convoluted T4 lymphocytes and occasional T10 lymphocytes. The T4:T8 ratio was 4:1. The antigen-presenting cells were mostly T6 negative (interdigitating reticulum cells). One case showed extensive paracortical expansion by small and large convoluted T4 lymphocytes. The T4:T8 ratio was 20:1. Few B lymphocytes and antigen-presenting cells were present. Two cases showed partial and one case total effacement by atypical lymphoid tissue. This included small and large convoluted T4 lymphocytes and T4 immunoblasts. The T4:T8 ratios were between 30 and 40:1. The changes in their antigen-presenting cell population were complex. Langerhans' cells in one case generally failed to express T6 antigen and in two displayed histiocyte features. In one case, both immature and budding type C retrovirus-like particles were identified in Langerhans cells. One extracellular mature type C virus-like particle was identified in another case. No ultrastructural distinction could be made between similarly sized primary lysosomes and possible intracytoplasmic mature type C retrovirus particles. These findings support the hypothesis that mycosis fungoides may represent an altered dermatonodal cycle resulting from an interaction between retrovirus, Langerhans' cells and lymphocytes.

Monoclonal antibodies and cutaneous T cell lymphoma. Theoretical and practical considerations

The T cell nature of mycosis fungoides and Sézary syndrome was established a decade ago. The recent advent of monoclonal antibodies to T cells and other lymphoid subpopulations has resulted in an explosion of knowledge on the biology of this group of disorders. These reagents have increased our knowledge on thymic differentiation status, pathogenesis, the phenotype of premalignant vs malignant lymphocytic infiltrates, the identification of other previously unrecognized cells within lymphomas, and the phenotype of circulating vs skin lymphocytes. Therapeutic applications may result. These new developments are discussed.

The intracutaneous growth of murine lymphomas: epidermal invasion is characteristic of multiple tumor phenotypes

Affinity of lymphoid cells for the epidermis (epidermotropism) is characteristic of the cutaneous T-cell lymphomas, mycosis fungoides and the Sézary syndrome. Consistent with numerous studies indicating that mycosis fungoides is a neoplasm of OKT4+T8- ("helper/inducer") T lymphocytes is the possibility that epidermotropism is a phenotypic hallmark of this subset of malignant T cells. This proposal was investigated in mice using 8 phenotypically characterized lymphomas of BALB/c origin: 3 histiocytic (phagocytic, lysozyme-positive, FcR+, Ig-, Thy 1-), 1 B-cell (IgM+, FcR+, Thy 1-), and 4 T-cell (Ig-, Thy 1+) lines, including 1 with markers of mouse helper/inducer T cells (Lyt1+23-), 2 with suppressor/cytotoxic markers (Lyt1-23+), and 1 with markers of immature thymocytes (Lyt1+23+). The intracutaneous growth pattern of these lines was studied on hematoxylin and eosin-stained sections through the centers of tumors obtained at times after intradermal injection into parallel groups of syngeneic mice. All of these lymphomas manifested variable epidermotropism that followed a typical sequence. Following dermal growth and spread to the dermal-epidermal junction, tumor cells appeared within the stratum spinosum. Subsequently, collections of cells appeared in spaces within the epidermis (Pautrier-like microabscesses) in tumors greater than 2 cm in diameter, coincident with early epidermal necrosis. Thus, in this animal model it is clear that the intraepidermal invasion/growth does not correlate with the helper/inducer T-cell surface phenotype. These observations are nonetheless consistent with recent studies using monoclonal antibodies to cell surface antigens which have demonstrated a heterogeneity of lymphoid cell subsets within the epidermis in lesions of mycosis fungoides and of other malignant and benign dermatoses.

Epidermal Langerhans' cells in Behçet's disease

Langerhans' cells were studied in the epidermis of two patients with active Behçet's disease and compared with those in two normal controls. Ultrastructural morphology and the percentage of Langerhans' cells found were similar in patients' (1.88%) and the control epidermis (1.79%). The density of Langerhans' cells in adjacent sites of the same epidermis was not homogeneous, being in the range of 0.8-2.8% in Behçet's disease and 0.6-4% in the controls. In the controls, Langerhans' cells were distributed unevenly. Some were located near the basal layer of the epidermis while the rest were in the mid and upper layers. In Behçet's disease most Langerhans' cells were in the mid-epidermis, but some were immediately beneath the stratum granulosum. In the Behçet's disease epidermis the area occupied by Langerhans' cells was increased by about 25% and the number of granules found increased by about 44%. It is suggested that in Behçet's disease the Langerhans' cells are in a more active state.

Lymphocyte function and chromosome aberrations in patients with early mycosis fungoides and parapsoriasis en plaques

Thirteen patients with stage I or II mycosis fungoides (MF) and 10 patients with large-plaque parapsoriasis en plaques (PEP) were examined for immunologic and cytogenetic disturbances. Total lymphocyte counts and immunoglobulin concentrations in the blood were normal. In vitro lymphocyte responses to polyclonal activators and various antigens in standard concentrations were normal. However, titration of phytohemagglutinin and concanavalin A (ConA) disclosed significantly lowered responses to suboptimal concentrations in the patient group, most pronounced in patients with MF II. ConA-induced leukocyte migration inhibitory factor (LIF) production, tested in an indirect leukocyte migration inhibitory assay, was low in the patient group. Furthermore spontaneous LIF production in vitro and small amounts of serum LIF were demonstrated in a few patients. The chromosomal banding pattern, sister chromatid exchange, and break frequency were within normal limits except for 3 translocations in the MF group. It is concluded that even in early-stage MF a pathologic function of blood lymphocytes can be demonstrated, when sensitive methods are applied. The findings might be important for monitoring disease activity and effect of treatment.

Antigens specified by the Tla locus are expressed on the surface of murine Langerhans cells

A monoclonal antibody against the murine thymus leukemia antigen TL, was employed to demonstrate the presence of the antigen on the surface of dendritic cells in murine epidermis of Tla-positive strains, B.10A and A.TH. Immunofluorescence and immunoperoxidase staining of EDTA-separated epidermal sheets demonstrated dendritic cells with a distribution pattern and density comparable to that noted for anti-IAk staining. Tla-negative mouse strains such as A.TL, C3H/HeJ, and C57BL/6 did not show any staining of dendritic epidermal cells. Epidermal cell suspensions similarly contained 2-4% cells with discrete surface staining with anti-TL antibody. Capping was noted in these cells. Once again positive results were noted only in appropriate Tla-positive strains. Control staining was carried out in all cases on frozen sections of thymii from mice. Thymocytes in the cortical zones and some dendritic cells at the corticomedullary junction were stained. TL antigen in mouse appears to be analogous to T-6 antigen previously detected on human Langerhans cells.

Lymphomatoid papulosis and Hodgkin's disease: are they related?

Two different characteristic types of lymphomatoid papulosis (type A and type B) can be histologically distinguished, that represent the ends of a spectrum. In the present report, two patients are described. One patient with both lymphomatoid papulosis type A and type B lesions for more than 25 years developed Hodgkin's disease (nodular sclerosing type) in the para-aortic and para-iliac lymph nodes. Histologic examination of the skin lesions in the second patient, who had Hodgkin's disease (nodular sclerosing type) in many supradiaphragmatic lymph nodes, showed the characteristic features of lymphomatoid papulosis type A. These findings, together with the results of recent immunohistochemical investigations showing many similarities between the large atypical cells in lymphomatoid papulosis type A lesions and Reed-Sternberg cells in Hodgkin's disease, support the view that lymphomatoid papulosis type A and Hodgkin's disease are closely related conditions. The results of recent studies indicate a close relationship between lymphomatoid papulosis type B and the early stages of mycosis fungoides. Accordingly, the possible relationship between lymphomatoid papulosis types A and B, mycosis fungoides, and Hodgkin's disease is discussed.

OKT 9 reactivity in mycosis fungoides and large plaque (atrophic) parapsoriasis

A monoclonal antibody OKT 9 which detects a determinant expressed by a variety of proliferating cell types has been recently developed. This antibody was used in conjunction with the immunoperoxidase technique to study the cutaneous lymphoid infiltrates of nine patients with mycosis fungoides, one patient with lymphomatoid papulosis, two patients with Sézary syndrome, and ten patients with large plaque atrophic parapsoriasis (a condition which may terminate in overt mycosis fungoides.) OKT 9 reactive cells were identified in all cases of mycosis fungoides examined, in one case of lymphomatoid papulosis, one of two cases of Sézary syndrome, and one of ten cases of large plaque atrophic parapsoriasis. These results suggest that further studies using OKT 9 should be performed to assess whether OKT 9 reactivity may be used as a prognostic marker in cutaneous lymphomas and prelymphomas.

A second look at intraepithelial Langerhans cells in mycosis fungoides and related disorders. Ultrastructural study with special reference to Langerhans granules and virus-like particles

Skin biopsies of patients with small and large plaque parapsoriasis, premycotic lesions and mycosis fungoides in different stages were examined. Special attention was paid to the relationships between Langerhans cells (LC) and the neighbouring keratinocytes and lymphocytes. At the contact areas of LC and keratinocytes as well as LC and lymphocytes, particular cell membrane phenomena were observed. Aggregations of Langerhans granules and fusions of granules with LC plasma membranes were found exclusively at LC-keratinocyte interfaces. At LC-lymphocyte contact zones cell membrane appositions were seen. In all cases investigated, virus-like particles were mainly found in LC and indeterminate cells (IDC). In 3 cases lymphocytes also contained these particles. It was of particular interest that virus-like particles were observed in skin specimens of all diseases investigated. Discrimination of these particles from other cellular organelles - especially lysosomes - was difficult, however. The significance of our findings, particularly regarding to the supposed virus aetiology of cutaneous T cell lymphomas, is discussed.

The clinical and histological spectrum of lymphomatoid papulosis

A review of sixty-four biopsies from sixteen patients with lymphomatoid papulosis revealed two characteristic histological types (type A and type B), which also had a different clinical behaviour. In lymphomatoid papulosis type A lesions, four histological patterns corresponding with the age of the lesion could be distinguished. Such a relationship was not found in type B lesions. The findings of transitional forms in some biopsy specimens, showing histological features of both type A and type B, and the presence of both types in different but concurrent lesions, suggests that these two types are not different entities but rather represent the ends of a spectrum. At least two different populations of atypical cells can be distinguished in lymphomatoid papulosis. Apart from the atypical cerebriform mononuclear cells, which are T-lymphocytic in origin and predominant in type B lesions, large atypical cells with vesicular nuclei, prominent nucleoli and abundant cytoplasm are found, particularly in type A lesions. Preliminary immunohistochemical and cytochemical investigations suggest that these cells are not lymphoid in origin, but are related to the Langerhans cell series.

Controversies in mycosis fungoides

Most clinicians agree that mycosis fungoides is the prototypic cutaneous T cell lymphoma. However, certain clinical characteristics indicate that this disorder may begin as a reactive rather than a neoplastic process. The concept of a nonneoplastic etiopathogenesis of mycosis fungoides is further supported by recent data on the function of Langerhans cells, a population of epidermal cells known to play a critical role in immune surveillance and the development of contact sensitivity. It has been suggested that chronic occupational exposure to environmental allergens results in persistent antigenic stimulation, leading to a breakdown in immune surveillance and eventually, malignancy. Modern laboratory technics have enhanced the clinician's ability to diagnose and stage mycosis fungoides. Data obtained from such studies have indicated that systemic spread may occur much earlier in the course of disease than has previously been appreciated. The therapeutic implications of such knowledge are as yet uncertain.

Ampliative medicament allergy: concomitant sensitivity to multiple medicaments including yellow soft paraffin, white soft paraffin, gentian violet and Span 20

A patient developed multiple rare medicament contact allergies including sensitivities to gentian violet, yellow and white soft paraffin, and Span 20 (sorbitan monolaurate). Nickel sensitivity antedated these medicament allergies. The possibility that nickel sensitivity is a marker of predilection to develop multiple medicament allergies was tested. We were unable to demonstrate an increased incidence of nickel sensitivity in a group of patients with 2 or more medicament allergies.

Demonstration of histiocytes in the epidermal infiltrate of mycosis fungoides

The presence of histiocytes in the epidermal and dermal infiltrate of mycosis fungoides was observed histochemically by revealing a diffuse pattern of acid alpha-naphthyl acetate esterase (ANAE) activity in the cytoplasm, and immunohistochemically by demonstrating the presence of histiocyte-specific 'enzymes', lysozyme, alpha-I-antitrypsin and alpha-I-antichymotrypsin. Histiocytes in the infiltrate of mycosis fungoides may be involved in antigen processing and interaction with T lymphocytes.

Demonstration of OKT 6-reactive cells in mycosis fungoides

Infiltrates of five cases of mycosis fungoides (MF) were studied for the presence of cells reactive with a monoclonal antibody, OKT 6, which detects an antigen present on relatively immature thymocytes and Langerhans cells. In situ immunohistochemical staining was used for their demonstration. OKT 6-reactive cells formed a definite component of the dermal infiltrates of all patients examined. In three patients who showed numerous Pautrier microabscesses on routine histologic examination, OKT 6-positive cells were found to form a component of these abscesses. OKT 6-reactive cells have also recently been shown to be present in varying numbers in the dermal infiltrates of large plaque (atrophic) parapsoriasis (LPAP), a condition which may terminate in MF. The significance of these findings is discussed.

The use of a double-label immunoperoxidase monoclonal antibody technique in the investigation of patients with mycosis fungoides

Using a double-labelling immunoperoxidase and monoclonal antibodies raised against T helper and T suppressor cells and Langerhans cells, we have found that the clinically involved skin of seventeen mycosis fungoides (MF) patients shows an increase in number of Langerhans cells which are in contact with T helper lymphocytes. T suppressor lymphocytes are also present, but are generally seen singly situated at a distance from the T helper/Langerhans cell clusters.

Morphologic and morphometric study of the two main cell lineages involved in mycosis fungoides: the lymphoid cells and the Langerhans cells

A comparative light and electron microscopic study was carried out on skin biopsies from 5 mycosis fungoides patients (stages II and III). In addition, certain zinc-iodide-osmium (ZIO) procedures that selectively reveal the Langerhans cells (LC) were also applied. Several morphometric analyses, such as relative frequency, cell size, nuclear:cell ratios and nuclear contour indexes, were performed. Two main cell lineages were found in the dermal infiltrate: the lymphoid cells, represented by lymphoblastlike cells (LB), lymphocytes (L), and mycosis fungoides cells (MFC), and the Langerhans cells. A pattern of cellular organization of the dermal infiltrate was recognized. The LC appeared as the "organizing" cell. The morphometric study indicated that all LB, L, and MFC have the chance, at the same time, to be in contact with a LC. The application of the ZIO procedures clearly indicated a "translocation" of the LC, since they were scarce or absent from the epidermis and numerous in the dermis. Evidence is presented indicating that differentiation of LB into L and malignant transformation of L into MFC are processes occurring predominantly in the dermis. It is postulated that in the chronic stages of mycosis fungoides, L-LC contacts occur mainly in the dermis and not in the epidermis and that the development of malignant clones may occur in the dermis.

In situ identification of Langerhans cells in the dermal infiltrate of cutaneous T cell lymphoma

A population of cells showing the surface phenotype of Langerhans cells (LCs) was identified in the dermal infiltrates of cutaneous T cell lymphoma (CTCL). Peroxidase-conjugated OKT6, a monoclonal antibody reactive with epidermal LCs, was used to directly label frozen tissue sections of diseased skin from twenty-three patients with CTCL, two patients with secondary cutaneous involvement by a B cell lymphoma, and three patients with lymphocytoma cutis. OKT6-reactive cells represented a significant although minor population in the dermal infiltrate of twenty-two of the twenty-three CTCL biopsies, accounting for up to 5% of the cells. Double-labeling studies revealed that the OKT6-positive cells also exhibited Ia but not T cell antigens. Since OKT6-reactive cells were not found in either the B cell lymphomas or lymphocytoma cutis, their presence in a malignant infiltrate is suggestive of a T cell neoplasm.