Palmoplantar peeling secondary to sirolimus therapy.

Sirolimus (rapamycin) is an immunosuppressive agent commonly used in transplant recipients. Although sirolimus has less renal toxicity than calcineurin inhibitors, its use has been limited by its side effects. The most common cutaneous pathologies associated with sirolimus are inflammatory acneiform eruptions, lymphedema and aphthous ulcers. We present a novel cutaneous manifestation of sirolimus therapy that limited its use in at least one transplant recipient. Upon commencing sirolimus therapy, four solid organ transplant recipients developed tender, nonpruritic palmoplantar peeling within the first month of therapy. The peeling clinically resembled a mild form of hand-foot syndrome, yet none of the patients had been treated with chemotherapeutics. Desquamation presented on the palms and soles with dry vesicles and minor peeling extending to the dorsal aspects of the hands and feet. Histologically, the lesions were noninflammatory; the epidermis showed subtle separation between keratinocytes, suggesting either spongiosis or a defect in intercellular adhesion. One patient opted to discontinue treatment because of the tenderness associated with the palmoplantar peeling, which resulted in complete resolution within 2 weeks.

A common human skin tumour is caused by activating mutations in beta-catenin.

WNT signalling orchestrates a number of developmental programs. In response to this stimulus, cytoplasmic beta-catenin (encoded by CTNNB1) is stabilized, enabling downstream transcriptional activation by members of the LEF/TCF family. One of the target genes for beta-catenin/TCF encodes c-MYC, explaining why constitutive activation of the WNT pathway can lead to cancer, particularly in the colon. Most colon cancers arise from mutations in the gene encoding adenomatous polyposis coli (APC), a protein required for ubiquitin-mediated degradation of beta-catenin, but a small percentage of colon and some other cancers harbour beta-catenin-stabilizing mutations. Recently, we discovered that transgenic mice expressing an activated beta-catenin are predisposed to developing skin tumours resembling pilomatricomas. Given that the skin of these adult mice also exhibits signs of de novo hair-follicle morphogenesis, we wondered whether human pilomatricomas might originate from hair matrix cells and whether they might possess beta-catenin-stabilizing mutations. Here, we explore the cell origin and aetiology of this common human skin tumour. We found nuclear LEF-1 in the dividing tumour cells, providing biochemical evidence that pilomatricomas are derived from hair matrix cells. At least 75% of these tumours possess mutations affecting the amino-terminal segment, normally involved in phosphorylation-dependent, ubiquitin-mediated degradation of the protein. This percentage of CTNNB1 mutations is greater than in all other human tumours examined thus far, and directly implicates beta-catenin/LEF misregulation as the major cause of hair matrix cell tumorigenesis in humans.

Blockade of CD2-LFA-3 interactions protects human skin allografts in immunodeficient mouse/human chimeras.

A human skin allograft injury model in immunodeficient mice, engrafted with human peripheral blood mononuclear cells from a different donor, has been used to test whether reagents that block human T cell CD2 interactions with its principal ligand, LFA-3 (CD58), can inhibit immune reactions in vivo. In this model, human skin grafts show a reproducible pattern of progressive human T-cell infiltration and human graft microvascular injury that resembles human first-set skin graft rejection. Murine Mab to human LFA-3 or human LFA-3-IgG1 fusion protein, but not isotype-matched control antibodies, each markedly protected skin grafts from leukocyte infiltration and injury. These data provide the first evidence that LFA-3 functions in vivo and establish the ability of this new model to test human-specific immune modulators.

Expression and targeting of the apoptosis inhibitor, survivin, in human melanoma.

The newly described apoptosis inhibitor survivin is expressed in many human cancers and appears to play a critical part in both apoptosis regulation and cell cycle progression. Its potential role in malignant melanoma is unknown. In a panel of 30 malignant melanomas, survivin was strongly expressed in all cases (15 of 15) of metastatic malignant melanomas and 13 of 15 cases of invasive malignant melanomas by immunohistochemistry. In invasive malignant melanomas, survivin was also expressed in the in-situ component of the lesion. Survivin expression was found in all cases (11 of 11) of nevi, but not in melanocytes in sections of normal skin. The apoptosis inhibitor bcl-2 was expressed in 26 of 30 cases, but generally at lower levels than that of infiltrating lymphocytes. The mitotic index, as assessed by MIB-1 staining, was consistently higher in metastatic than invasive malignant melanomas. Assessment of apoptotic index by in situ end-labeling revealed extremely low rates of apoptosis in most malignant melanomas. Survivin expression by western blotting was detected in four human metastatic malignant melanoma cell lines but not in cultured normal human melanocytes. Transfection of both YUSAC-2 and LOX malignant melanoma cells with green fluorescence protein-conjugated survivin anti-sense or green fluorescence protein-conjugated survivin dominant negative mutant (Cys84Ala) [corrected] resulted in increased apoptosis in the absence of other genotoxic stimuli. Two-color flow cytometry confirmed that YUSAC-2 cells transfected with survivin anti-sense expressed less endogenous survivin and exhibited an increased fraction of cells with sub-G1 DNA content. These data demonstrate that apoptosis inhibition by survivin may participate in the onset and progression of malignant melanomas, and suggest that therapeutic targeting of survivin may be beneficial in patients with recurrent or metastatic disease.

Melanoma x macrophage hybrids with enhanced metastatic potential.

Studies were conducted on the hypothesis that melanoma metastasis might be initiated through the generation of hybrids comprised of cells of the primary tumor and tumor-infiltrating leukocytes. Fusion hybrids were generated in vitro between weakly metastatic Cloudman S91 mouse melanoma cells and normal mouse or human macrophages. Hybrids were implanted s.c. in the tail and mice were monitored for metastases. Controls included parental S91 cells, autologous S91 x S91 hybrids, and B16F10 melanoma cells. Of 35 hybrids tested, most were more aggressive than the parental melanoma cells, producing metastases sooner and in more mice. A striking characteristic was heterogeneity amongst hybrids, with some lines producing no metastases and others producing metastases in up to 80% of mice. With few exceptions, hybrids with the highest metastatic potential also had the highest basal melanin content whereas those with the lowest metastatic potential were basally amelanotic, as were the parental melanoma cells. A spontaneous in vivo supermelanotic hybrid between an S91 tumor cell and DBA/2J host cell was one of the most metastatic lines. Hybrids with the highest metastatic potential also exhibited markedly higher chemotaxis to fibroblast-conditioned media. Histologically, the metastatic hybrids demonstrated vascular invasion and spread to distant organs similar to that of metastatic melanomas in mice and humans. Thus previous findings of enhanced metastasis in leukocyte x lymphoma hybrids can now be extended to include leukocyte x melanoma hybrids. Whether such hybridization is a natural cause of metastasis in vivo remains to be determined; however the fusion hybrids with genetically-matched parents described herein so closely resembled naturally-occurring metastatic melanoma cells that they could serve as useful new models for studies of this complex and deadly phenomenon.

Ancylostoma caninum anticoagulant peptide blocks metastasis in vivo and inhibits factor Xa binding to melanoma cells in vitro.

We evaluated the in vivo anti-metastatic activity of recombinant Ancylostoma caninum Anticoagulant Peptide (rAcAP), a potent (Ki = 265 pM) and specific active site inhibitor of human coagulation factor Xa originally isolated from bloodfeeding hookworms. Subcutaneous injection of SCID mice with rAcAP (0.01-0.2 mg/mouse) prior to tail vein injection of LOX human melanoma cells resulted in a dose dependent reduction in pulmonary metastases. In order to elucidate potential mechanisms of rAcAP's anti-metastatic activity, experiments were carried out to identify specific interactions between factor Xa and LOX. Binding of biotinylated factor Xa to LOX monolayers was both specific and saturable (Kd = 15 nM). Competition experiments using antibodies to previously identified factor Xa binding proteins, including factor V/Va, effector cell protease receptor-1, and tissue factor pathway inhibitor failed to implicate any of these molecules as significant binding sites for Factor Xa. Functional prothrombinase activity was also supported by LOX, with a half maximal rate of thrombin generation detected at a factor Xa concentration of 2.4 nM. Additional competition experiments using an excess of either rAcAP or active site blocked factor Xa (EGR-Xa) revealed that most of the total factor Xa binding to LOX is mediated via interaction with the enzyme's active site, predicting that the vast majority of cell-associated factor Xa does not participate directly in thrombin generation. In addition to establishing two distinct mechanisms of factor Xa binding to melanoma, these data raise the possibility that rAcAP's antimetastatic effect in vivo might involve novel non-coagulant pathways, perhaps via inhibition of active-site mediated interactions between factor Xa and tumor cells.

Extracorporeal photochemotherapy in human and murine graft-versus-host disease.

Extracorporeal photochemotherapy (ECP) is an immunotherapy that has found a role in the therapy of cutaneous T cell lymphoma, a disease of mature activated T cells. Graft-versus-host disease (GVHD) is also mediated by activated T cells, and thus often responds to therapies that target T cells. Murine models for both GVHD and ECP can be combined to study the impact of this immunotherapy on GVHD. In this paper we present a patient with GVHD who demonstrated a beneficial therapeutic response to treatment with ECP. The findings of this case are compared with the observations from a murine model for GVHD-ECP. The potential mechanisms of ECP in the treatment of GVHD are discussed. along with the similarities observed with ECP in the treatment of other conditions.

Permeability characteristics of cultured endothelial cell monolayers.

The purpose of this study was to characterize the permeability characteristics of an in vitro endothelial cell monolayer system and relate this information to available in vivo data. We cultured bovine fetal aortic endothelial cells on fibronectin-coated polycarbonate filters and confirmed that our system was similar to others in the literature with regard to morphological appearance, transendothelial electrical resistance, and the permeability coefficient for albumin. We then compared our system with in vivo endothelium by studying the movement of neutral and negatively charged radiolabeled dextran tracers across the monolayer and by using electron microscopy to follow the pathways taken by native ferritin. There were a number of differences. The permeability of our monolayer was 10-100 times greater than seen in intact endothelium, there was no evidence of "restricted" diffusion or charge selectivity, and ferritin was able to move freely into the subendothelial space. The reason for these differences appeared to be small (0.5-2.0 micron) gaps between 5 and 10% of the endothelial cells. Although the current use of cultured endothelial cells on porous supports may provide useful information about the interaction of macromolecules with the endothelium, there appear to be differences in the transendothelial permeability characteristics of these models and in vivo blood vessels.

Psoralen photochemotherapy, clinical efficacy, and photomutagenicity: the role of molecular epidemiology in minimizing risks.

Photochemotherapy employing 8-methoxypsoralen and ultraviolet radiation (PUVA) is widely used in the treatment of psoriasis. The photoactivation of psoralens in skin cells leads to DNA photoadduct formation which may be responsible for the efficacy of PUVA. Subsequent mutations may lead to the increased incidence of squamous cell carcinoma (SCC). Mutations in the p53 tumor suppressor gene have been detected in many human cancers. In this review, p53 mutation spectra in murine and human SCC are compared to those obtained from murine cells and skin treated with PUVA as well as to the p53 mutation spectrum in human solar SCC. While the expected psoralen-type mutations at alternating AT sites were detected in the treated cells and murine SCC (average frequency > 40%), such mutations were not commonly detected in the human SCC (< 10%). Other common mutations in the human SCC included: CG-->TA transitions (18%) and CG-->AT and TA-->GC transversions (17 and 25%, respectively). In addition, the frequency of UVB-type mutations at dipyrimidine sites (CC-->TT) in the SCC PUVA-treated psoriasis patients was comparable to that in patients with SCC from only solar exposure. A review of therapeutic history of these patients showed that many had also received UVB phototherapy. Furthermore, because sunlight is thought to be beneficial for psoriasis, nontherapeutic, casual UVB exposure cannot be excluded. Thus, the PUVA SCC may have arisen from the solar mutations and PUVA may enhance tumor progression by other epigenetic effects.

Lymphomatoid granulomatosis of the skin and lung. An angiocentric T-cell-rich B-cell lymphoproliferative disorder.

OBJECTIVE: To test the recent hypothesis that lymphomatoid granulomatosis (LYG) is a clonal B-cell proliferative process related to Epstein-Barr virus (EBV). BACKGROUND AND DESIGN: Historically, LYG has been classified as an angiocentric T-cell lymphoproliferative disorder. To further characterize LYG in the skin, we analyzed for EBV RNA in lymphocytes using in situ hybridization, coupled with colabeling for B-cell and T-cell markers. Clonality of lymphocytes was assessed by polymerase chain reaction using primers for immunoglobulin heavy chain genes and T-cell receptor beta and gamma genes. SETTING: Academic referral center. PATIENTS: In a 5-year retrospective review, we identified 4 patients with classic clinical and pathologic features of LYG in skin and lung, and tissue available from both sites. MAIN OUTCOME MEASURES: The presence or absence of EBV RNA and clonal gene rearrangements in cutaneous and pulmonary lesions of LYG. RESULTS: Biopsy specimens of skin and lung in all patients revealed angiocentric infiltrates predominantly composed of T lymphocytes. Epstein-Barr virus RNA was identified in the skin of 1 patient and the lung of 3 patients, and was restricted to B cells. Polymerase chain reaction revealed clonal immunoglobulin heavy chain gene rearrangements and no clonal rearrangement of T-cell receptor genes in skin and lung tissue of all patients. CONCLUSIONS: At least some examples of LYG in the skin and lung are characterized by a clonal proliferation of B lymphocytes, some of which contain EBV RNA. The B cells are typically scarce and may be obscured by striking angiocentric T-cell infiltrates.

Discoid lupus erythematosus presenting as asymmetric posterior blepharitis.

PURPOSE: To describe the ophthalmic findings of patients with discoid lupus erythematosus. METHOD: We describe two women who originally were thought to have asymmetric posterior blepharitis; however, the involved eyelid also had an erythematous, scaly cutaneous lesion. RESULT: In both patients, histology and immunofluorescence studies performed on cutaneous biopsy specimens established the diagnosis of discoid lupus erythematosus. CONCLUSIONS: It is important to diagnose discoid lupus of the eyelids because misdiagnosis can delay treatment and thus lead to deformities of the eyelid margin. Misdiagnosis can also lead to a complicated full-thickness eyelid biopsy and delay the diagnosis of systemic lupus erythematosus.

An unexpected spectrum of p53 mutations from squamous cell carcinomas in psoriasis patients treated with PUVA.

Photochemotherapy employing 8-methoxypsoralen and long-wavelength ultraviolet radiation (UVA, 320-400 nm) is widely used in the treatment of psoriasis. The photoactivation of psoralens in skin cells leads to formation of DNA photoadducts which may be responsible, at least in part, for the efficacy of these photochemotherapies. However, mutations arising from these adducts may also lead to the well-characterized increased incidence of squamous cell carcinoma. Mutations in the p53 tumor suppressor gene have been detected in many human cancers. To determine whether p53 mutations occur in squamous cell carcinomas in PUVA patients, PCR was used to amplify the exons (5-9) in which other studies have found a high frequency of point mutations. Gel electrophoresis was used to detect single-strand conformational polymorphisms. Aberrantly migrating bands were excised, reamplified and sequenced. Thirty-four specimens from 10 patients were examined. Specimens from one patient who had received no phototherapy as well as from normal controls were also analyzed. Five of the 10 patients showed at least one p53 mutation. In contrast to previously reported psoralen-induced p53 mutations in mice, the expected psoralen type mutations at alternating AT sites were not detected. All but two of the altered sequences occurred at dipyrimidine sites which is typical of solar type mutations. Two C-->T mutations and two dipyrimidine mutations (CC-->TT) were found. Other mutations included: C-->G, G-->T, C-->A and an 18 bp deletion. A review of therapeutic history of these patients showed that some had also received UVB phototherapy. Furthermore, because sunlight is thought to be beneficial for psoriasis, nontherapeutic, casual UVB exposure cannot be excluded. Our observations suggest that the SCC may have arisen from the solar mutations and that PUVA may enhance tumor progression or immune suppression.

Cutaneous T-cell lymphoma. Refinement in the application of controversial histologic criteria.

The term cutaneous T-cell lymphoma was originally coined to encompass the spectrum of mycosis fungoides and Sézary syndrome. It has become increasingly evident that the histopathologic diagnosis of CTCL can be exceedingly challenging. A series of recent studies, however, have helped clarify the nature of the histologic findings in CTCL. Recently reported histologic data on mycosis fungoides, Sézary syndrome, and their variants is emphasized in this article, with special focus given to the findings in early lesions. A brief summary of lymphocyte immunophenotyping and the role of T-cell reception gene rearrangements in CTCL is included.

Under the microscope. Surgeons, pathologists, and melanocytic nevi.

Predicting the biologic behavior of melanocytic neoplasms (benign versus malignant) based on histology is one of the most difficult challenges in surgical pathology and dermatology. Success in the field of melanocytic neoplasia can be achieved by two means: performing excisions or biopsies that maximize the obtainable histologic information and providing sufficient history.

Epithelioid cell histiocytoma: a simulant of vascular and melanocytic neoplasms.

Epithelioid cell histiocytoma (ECH) is an unusual and still poorly recognized variant of benign fibrous histiocytoma. Epithelioid cell histiocytoma differs from most benign fibrous histiocytomas in five important ways: the predominance of epithelioid cells, relative lack of secondary elements (such as giant cells, foamy, or hemosiderin-laden macrophages), relative sharp circumscription, prominent vascularity, and centering in the papillary dermis in most cases. A strong resemblance to melanocytic and vascular lesions has been noted, and a recent case was reported with features suggesting endothelial origin. Fifteen new cases of ECH, including one example of the rare deep cellular variant, are presented herein, with emphasis on features mimicking vascular and melanocytic neoplasms. Labeling with endothelial markers, including previously unreported CD-31 labeling, showed abundant vascular staining, which may be challenging to interpret, but which does not indicate an endothelial origin of ECH.

Secretion of Weibel-Palade bodies observed in extra-alveolar vessels of rabbit lung.

We fixed rabbit lungs by perfusion of osmium into the pulmonary artery and examined in light and transmission electron microscopy a large number of extra-alveolar vessels with a diameter of 0.1-0.25 mm, with emphasis on Weibel-Palade bodies (endothelial specific granules). Weibel-Palade bodies are organelles specific to endothelial cells. Their function is unknown, but they are useful markers for identification of endothelial cells in culture. We were able to observe release of the content of these bodies into the vascular lumen; this indicates that they are secretory.

Early tissue damage in ethchlorvynol-induced alveolar edema in rabbit lung.

The purpose of this study was to examine the morphologic changes that occur in the early stages of intraalveolar edema. Anesthetized rabbits were intravenously administered a bolus of 40 mg/kg of ethchlorvynol, a mild hypnotic known to induce respiratory distress syndrome in humans and laboratory animals when given intravenously. After 15 min their lungs were fixed for transmission electron microscopy. Examination revealed variable amounts of irregularly distributed intraalveolar edema with erythrocytes and fibrin strands that coexisted with modest or nonexisting interstitial edema suggesting that primary hemorrhagic alveolar flooding had taken place. Most alveolar epithelial and endothelial cells appeared normal except in localized areas. In lungs fixed by vascular perfusion, in which normal capillaries were flushed, obstructions were noticed in alveolar corner capillaries. These areas were identified by light microscopy and selectively sectioned for electron microscopy. They contained intravascular cell-fibrin aggregates consisting of plugs of degranulated platelets, fibrin, erythrocytes, and leukocytes. Endothelial and epithelial cells in the vicinity of the plugs showed variable degrees of injury. In places the damage was so severe that vascular and alveolar spaces were separated only by the basal lamina. Our work shows the previously unnoticed existence of capillary microemboli or microthrombi in a well-known experimental model of respiratory distress syndrome and suggests extravasation of blood elements through discrete sites of cell injury associated with the fibrin-platelet aggregates rather than diffuse increase of permeability as cause of early alveolar flooding.

Early cell alterations induced by histamine and epinephrine in rabbit lung.

This study was concerned with the early effects on lung cells of infusion of 18 micrograms/kg histamine to the rabbit. For comparison purposes, other rabbits received a bolus of 0.4 micrograms/kg epinephrine. After administration, the lungs were immediately fixed by vascular perfusion of osmium tetroxide. In the group that received histamine, we observed selective alterations in the type I epithelial cells of the alveolar wall, consisting of localized thickening, increased number of cytoplasmic ribosomes, and homogeneity and increased electron density with reduction of the number of plasmalemmal vesicles. These alterations were quantitated; the vesicular load (no. of vesicles/cm2) was computed separately for each cell front of epithelial and endothelial cells. Epinephrine induced only edema in epithelial and endothelial cells, resulting in high electron lucency, thickening, and irregular cell profiles. We interpret the alterations seen in histamine-treated animals as reflecting uptake of histamine by the alveolar epithelium leading to an increased level of metabolic activity. Histamine induced no interstitial edema and no immediate reduction of capillary volume. The cellular edema related to epinephrine, a substance which is not taken up or metabolized by the lung, represented a form of cell injury.