Loss of function of ENT3 drives histiocytosis and inflammation through TLR-MAPK signaling.

Histiocytoses are inflammatory myeloid neoplasms often driven by somatic activating mutations in mitogen-activated protein kinase (MAPK) cascade genes. H syndrome is an inflammatory genetic disorder caused by germ line loss-of-function mutations in SLC29A3, encoding the lysosomal equilibrative nucleoside transporter 3 (ENT3). Patients with H syndrome are predisposed to develop histiocytosis, yet the mechanism is unclear. Here, through phenotypic, molecular, and functional analysis of primary cells from a cohort of patients with H syndrome, we reveal the molecular pathway leading to histiocytosis and inflammation in this genetic disorder. We show that loss of function of ENT3 activates nucleoside-sensing toll-like receptors (TLR) and downstream MAPK signaling, inducing cytokine secretion and inflammation. Importantly, MEK inhibitor therapy led to resolution of histiocytosis and inflammation in a patient with H syndrome. These results demonstrate a yet-unrecognized link between a defect in a lysosomal transporter and pathological activation of MAPK signaling, establishing a novel pathway leading to histiocytosis and inflammation.

Can CD44 Be a Mediator of Cell Destruction? The Challenge of Type 1 Diabetes.

CD44 is a multi-functional receptor with multiple of isoforms engaged in modulation of cell trafficking and transmission of apoptotic signals. We have previously shown that injection of anti-CD44 antibody into NOD mice induced resistance to type 1 diabetes (T1D). In this communication we describe our efforts to understand the mechanism underlying this effect. We found that CD44-deficient NOD mice develop stronger resistance to T1D than wild-type littermates. This effect is not explained by the involvement of CD44 in cell migration, because CD44-deficient inflammatory cells surprisingly had greater invasive potential than the corresponding wild type cells, probably owing to molecular redundancy. We have previously reported and we show here again that CD44 expression and hyaluronic acid (HA, the principal ligand for CD44) accumulation are detected in pancreatic islets of diabetic NOD mice, but not of non-diabetic DBA/1 mice. Expression of CD44 on insulin-secreting ß cells renders them susceptible to the autoimmune attack, and is associated with a diminution in ß-cells function (e.g., less insulin production and/or insulin secretion) and possibly also with an enhanced apoptosis rate. The diabetes-supportive effect of CD44 expression on ß cells was assessed by the TUNEL assay and further strengthened by functional assays exhibiting increased nitric oxide release, reduced insulin secretion after glucose stimulation and decreased insulin content in ß cells. All these parameters could not be detected in CD44-deficient islets. We further suggest that HA-binding to CD44-expressing ß cells is implicated in ß-cell demise. Altogether, these data agree with the concept that CD44 is a receptor capable of modulating cell fate. This finding is important for other pathologies (e.g., cancer, neurodegenerative diseases) in which CD44 and HA appear to be implicated.

A novel urine cytology stain for the detection and monitoring of bladder cancer.

PURPOSE: CellDetect® is a unique platform technology comprising a proprietary plant extract and 3 dyes that enables color discrimination between malignant (red) and benign (green) cells based on specific metabolic alterations exclusive to the former. Preclinical studies and clinical trials demonstrated the applicability of the new technology in many cell culture lines and various cancers. We explored its performance characteristics in bladder cancer. MATERIALS AND METHODS: We performed an open label, 2-step study at tertiary medical centers. The study enrolled patients with newly diagnosed or a history of urothelial carcinoma. Step 1 involved staining archived biopsies. Slides were evaluated by 2 independent pathologists, who determined the concordance of the new staining technology with the hematoxylin and eosin based diagnosis. Step 2 included staining urine specimens with the new method and comparing findings to the patient final diagnosis and the results of standard urine cytology. RESULTS: A total of 58 archived biopsies were collected. The concordance of staining using the new platform technology with the hematoxylin and eosin based diagnosis was 100%. The new method applied to 44 urine smears showed 94% sensitivity and 89% specificity to detect urothelial carcinoma. Compared to standard urine cytology the new technology had overall superior sensitivity (94% vs 46%), particularly for low grade tumors (88% vs 17%, each p <0.005). There was no significant difference in specificity between the 2 staining techniques. CONCLUSIONS: Findings show the capability of CellDetect to accurately identify urothelial carcinoma. This indicates that the technology can be further developed to provide an alternative urine cytology test with diagnostic value that may have significant clinical benefits.

Novel dual-function CellDetect® staining technology: wedding morphology and tinctorial discrimination to detect cervical neoplasia.

BACKGROUND: A persistent goal of oncologic histochemistry is to microscopically identify neoplasia tinctorially. Consequently, the newly developed CellDetect® staining technology, that appears to exhibit this property, warrants clinical evaluation. The objective of this study was to compare the diagnostic results using CellDetect® to the outcomes of standard microscopic examination based on hematoxylin and eosin (H&E) staining for the recognition of different squamous epithelial phenotypes of the uterine cervix. METHODS: Pairs of adjacent sections were made from 60 cervical biopsy cases that were diagnosed originally as either normal or neoplastic (CIN, SCC). One section of the pair was stained for H&E; the second section, with CellDetect®. Based on the examination of these pairs by two experienced pathologists, we investigated the following issues:(1) diagnostic agreement between the pathologists on each pair; (2) agreement between H&E and CellDetect® for each pair (3) tinctorial characteristics in micro-regions (n = 130) evaluated as either normal, reactive or neoplastic. RESULTS: Qualitatively, CellDetect®-stained preparations displayed cyto-morphological detail comparable to H&E images. Tinctorially, non-neoplastic cells appeared green/blue when stained withCellDetect®, contrasting with cytologically neoplastic foci, where cells of every grade were red/magenta in color. Due to these tinctorial characteristics, even small foci of neoplasia could be readily distinguished that were inconspicuous on H&E at low magnification. In some instances, this prompted re-examination of the H&E and revision of the diagnosis. Quantitatively, we found that despite diagnostic variation between pathologists, in about 3% of the cases, each pathologist made the same diagnosis regardless of whether CellDetect® or H&E was used, i.e. there was 100% self-agreement for each pathologist between stains. Particularly noteworthy was the finding of a 0% false negative rate, coupled with a 10-15% false positive rate. Regarding specificity, the performance in reactive squamous processes was similar to that observed for morphologically normal squamous epithelium. CONCLUSIONS: In this first order assessment of clinical applicability, CellDetect® staining technology was at least comparable to results using H&E, and perhaps surperior. CellDetect® provided a uniquely useful tinctorial clue for the detection of neoplasia, which exhibited an impressive 0% false negative rate. A more extensive, blinded study is needed to confirm these promising findings.

Different patterns of expression of the erbB family of receptor tyrosine kinases in common nevi, dysplastic nevi, and primary malignant melanomas: an immunohistochemical study.

erbB receptors contribute to tumor formation and progression. Variable expression of erbB1, erbB2, and erbB3 has been reported in nevi and melanomas; erbB4 has hardly been investigated. We examined the expression of all 4 erbB receptors in common and dysplastic nevi and melanomas. Formalin-fixed, paraffin-embedded tissues of 100 melanomas, 27 common nevi, and 23 dysplastic nevi were immunostained with antibodies against the 4 erbB receptors. erbB3 and erbB4 showed stronger positivity in nevi than in melanomas, and in common than in dysplastic nevi. Staining pattern was more orderly in nevi than in melanomas. Common nevi showed more prominent membranous staining for erbB3 than dysplastic nevi followed by melanomas. In melanomas, greater thickness was associated with more widespread erbB2 and erbB3 staining in the vertical than in the radial growth phase, and in the dermal than in the epidermal component. Higher mitotic counts were associated with more widespread and intense erbB2 expression in the vertical growth phase than in the radial growth phase and in the dermal than in the epidermal component. Melanomas with more widespread erbB2 staining had heavier lymphocytic infiltrates. erbB1 expression was negligible in all groups. erbB2, erbB3, and erbB4 are expressed in all subtypes of melanocytic lesions, but with quantitative and qualitative differences. Receptor expression seems to decrease and to become less mature and orderly with tumor progression. The complex patterns of erbB receptor expression in melanocytic lesions warrant further investigation.

Role and prognostic significance of the Ki-67 index in non-Hodgkin's lymphoma.

Expression of Ki-67, a nuclear antigen protein present in all cycling cells, is used to determine the growth fraction of tumors. The aim of this study was to evaluate the role and prognostic significance of the Ki-67 proliferation index (PI) in non-Hodgkin's lymphoma. Ki-67 was assayed immunohistochemically in tissue samples of 319 patients with newly-diagnosed non-Hodgkin's lymphoma. In 268 patients, the Ki-67 PI was correlated with clinical course and outcome. The mean Ki-67 PI ranged from 26.6% in indolent lymphomas to 97.6% in very aggressive lymphomas (P < 0.001). The index was <45% in 82.8% of indolent lymphomas and >45% in 85% of aggressive lymphomas (AUC = 0.877, P < 0.001). In patients with diffuse large B-cell lymphoma (n = 141), a Ki-67 PI of 70% was found to significantly discriminate patients with good or bad prognosis (AUC = 0.65, P = 0.004). Three-year survival was 75% +/- 5.6% in patients with a low Ki-67 index compared with 55.9% +/- 6% in patients with a high index (P = 0.015). In patients with a low IPI (10 cm), the corresponding 3-year survival by Ki-67 index was 100% and 25% +/- 12% (P = 0.012). Our results suggest that the mean Ki-67 PI differs by type of lymphoma. A cut-off value of 45% can help differentiate indolent from aggressive disease. In diffuse large B-cell lymphoma, a cut-off value of 70% can distinguish patients with a good and bad prognosis when combined with other prognostic factors of low IPI score and bulky disease.

Gelatinous transformation of bone marrow in chronic myeloid leukemia during treatment with imatinib mesylate: a disease or a drug effect?

Gelatinous marrow transformation (GMT) is an unusual pathological manifestation of progressive malignant diseases and severe malnutrition states. GMT has been associated with various accelerated hematological malignancies, but has never been described in patients with chronic myelogenous leukemia (CML) treated with imatinib mesylate (IM), a novel tyrosine kinase inhibitor. Herein we report 2 patients with stable chronic phase CML who developed GMT during the course of treatment with IM. A comprehensive review of the relevant published data, several possible mechanisms and therapeutic alternatives are suggested.

Expression of VEGF-C, VEGF-D and their receptor VEGFR-3 in diffuse large B-cell lymphomas.

Lymphangiogenesis-the new growth of lymphatic vessels is an important route for the metastatic spread of human cancer. The receptor tyrosine kinase VEGFR-3 is expressed predominantly on lymphatic endothelium, and activation by its ligands VEGF-C and VEGF-D induces lymhpangiogenesis. VEGF-C, VEGF-D and VEGFR-3 have been found to play an important role in the lymphangiogenesis of several cancers. The present study investigated the expression of these factors by immunohistochemical staining of diagnosis specimens from 38 patients with diffuse large B-cell lymphoma (DLBCL). VEGF-C, VEGF-D and VEGFR-3 were expressed in both lymphoma cells and endothelial cells of blood and lymphatic tissue in all but one patient (who was negative for VEGF-D in lymphoma). There was a significant correlation in the intensity of staining between VEGF-C and -D in lymphoma and blood vessels (P < 0.001), and between the intensity of staining of VEGF-D and the patient International Prognostic Index score (P = 0.049) and borderline significance with overall survival (P = 0.051). Mean microvessel count was 58 (range 23-120), and it increased in association with high-intensity VEGF-C staining in lymphoma cells. Our findings indicate the importance of lymphangiogenic factors in the pathogenesis of DLBCL and suggest a potential therapeutic role for antilymphangiogenesis agents.

Repeated low-dose of erythropoietin is associated with improved left ventricular function in rat acute myocardial infarction model.

OBJECTIVE: To evaluate the potential protective affects of Epo on left ventricular (LV) function and remodeling after acute myocardial infarction (MI). METHODS: Epo was injected into the peritoneum of male Wistar rats (250 g) during 6 weeks post induction of MI. Rats were divided into five groups: MI treated with single high dose (MT1, 5,000 U/kg, n=10), single high dose (5,000 U/kg) and repeated high doses (MTHi, 1,000 U/kg twice a week; n=8), or single high dose (5,000 U/kg) and repeated low doses (MTLo, 750 U/kg once a week, n=10), MI non-treated (MNT, n=10), sham (S, n=5). Echocardiography was performed 3.6+/-1.5 days and 43.7+/-2.3 days post MI. Collagen deposition and infarct size were measured on histological sections using computerized image analysis. Apoptosis was assessed by ApopTag staining. RESULTS: Baseline fractional shortening (FS) was similar between groups. Six weeks after MI the FS of MTLo (26.9%) was significantly higher compared to MNT (17.8%), MT1 (19.5%) and MTH (22.3%) (p=0.01). However, remodeling indices (end diastolic and end systolic areas, LV circumference) did not improve in the Epo groups, and even worsened in the MTHi group. There was significantly less collagen staining in non-infarct areas in MT1 and MTHi groups compared to MNT and MTLo (0.38+/-0.3%, 0.49+/-0.34%, vs 0.89+/-0.41%, 0.95+/-0.33%, respectively, p<0.001). The number of ApopTag positive nucleus was significantly higher in the MNT group compared to the MT1, MTHi, MTLo groups (14.4+/-8, 7.6+/-4, 5.8+/-7, 4.8+/-5, respectively, p=0.01 for trend). CONCLUSION: Repeated low doses of Epo after MI improved LV function, but the role of Epo on remodeling is not clear. It did not reduce left ventricular indices, but reduces fibrosis and apoptosis. High Epo doses reduced LV function and aggravated remodeling.

Traumatic ulcerative granuloma with stromal eosinophilia: a reactive lesion of the oral mucosa.

Traumatic ulcerative granuloma with stromal eosinophilia (TUGSE) is a benign lesion of the oral mucosa of an unclear pathogenesis. We analyzed the profile of the inflammatory infiltrate in 12 cases of TUGSE by using immunohistochemical analysis and polymerase chain reaction-based repertoire analysis to detect T- and B-cell receptor gene rearrangements. The inflammatory infiltrate consisted in most cases of B and T lymphocytes, macrophages, abundant eosinophils, and large atypical cells. In 5 cases, CD30+ cells were found. Spectratyping analysis displayed a polyclonal rearrangement of the T-cell receptor g gene in 6 cases and oligoclonality in 5 cases. Monoclonality was observed in 1 case that also fulfilled histologic criteria for lymphoma. Healing was uneventful in all cases, including the one suspected of being lymphoma, with no recurrences in more than 2 years'follow-up. TUGSE can be regarded reactive. Some cases, however, may harbor a dominant clonal T-cell population; in these cases, long-term follow-up is mandatory.

Sister Mary Joseph's nodule as the first presenting sign of primary fallopian tube adenocarcinoma.

Umbilical metastasis (Sister Mary Joseph's nodule) is often the first sign of intraabdominal and/or pelvic carcinoma. We describe the fourth case reported in the literature of Sister Mary Joseph's nodule originating from fallopian tube carcinoma. In a 54-year-old woman, Sister Mary Joseph's nodule was unexpectedly detected during umbilical hernia repair. Subsequent laparoscopy revealed a 2-cm friable tumor located at the fimbriated end of right fallopian tube and 1-cm peritoneal implant in the pouch of Douglas. Laparoscopic bilateral adnexectomy and resection of the peritoneal implant were performed. Because frozen section examination revealed fallopian tube carcinoma, the procedure was continued with laparotomy including total abdominal hysterectomy, omentectomy, and pelvic lymph node sampling. Final diagnosis was stage IIIB fallopian tube carcinoma. The patient received postoperative adjuvant chemotherapy with single-agent carboplatin and has remained alive and with no evidence of disease. It is concluded that in cases of Sister Mary Joseph's nodule, laparoscopy can be a useful tool in the search of the primary tumor in the abdomen and/or pelvis. Laparoscopy can provide crucial information with respect to the location, size, and feasibility of optimal surgical resection of the intraabdominal and/or pelvic tumors.

c-kit expression in primary and metastatic merkel cell carcinoma.

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumor of the skin that is associated with a high incidence of recurrence and metastasis. The therapeutic arsenal for this malignancy is limited and once it spreads, there is no effective treatment. c-kit expression has been demonstrated previously in primary MCCs thus raising the possibility of treating MCCs with imatinib mesylate, the tyrosine kinase inhibitor that has shown promise in the management of c-kit expressing tumors. In this study we examine 25 additional primary MCCs and also 6 of their lymph node metastases. Formalin-fixed, paraffin-embedded tissues were stained immunohistochemically with an antibody directed against the KIT receptor. Percentage and intensity of staining were analyzed semiquantitatively using a three-tiered system. Twenty-one of the 25 (84%) primary tumors stained positively for KIT, of which 14 (67%) showed widespread positivity. Five of the 6 lymph nodes (83%) were similarly positive. High mitotic rate and vascular invasion in the primary tumors tended to be associated with prominent staining in the lymph node metastases. No association was found between c-kit expression and outcome. We confirm that the majority of primary MCCs express c-kit and further find that metastases are positive for the KIT receptor as well. Thus, c-kit expression may be an early event in the transformation of MCC, but not a marker for tumor progression.

Histologic and immunohistochemical characterization of tumor and inflammatory infiltrates in oral squamous cell carcinomas treated with local multikine immunotherapy: the macrophage at the front line.

Squamous cell carcinomas of the head and neck (SCCHN) are excellent candidates for local immunotherapy owing to their accessibility and their infiltration by mononuclear cells that are susceptible to immunomodulation. A response rate of 25-60% has been reported for treatment with natural IL-2 or a mixture of natural lymphokines. In the present study, biopsies and posttreatment excision specimens from nine patients with operable SCCHN treated systemically with a variety of immunomodulators and locally with natural lymphokines (multikine, CelSci) were analyzed in an attempt to correlate clinical response to histopathological and immunohistochemical changes. Formalin-fixed, paraffin-embedded tissues were stained with antibodies against lymphocytes (CD45, CD3, CD4, CD8, CD20), macrophages (CD68) including dendritic cells (S-100), markers for lymphocyte activation (CD30, HLA-DR), natural killer cells (CD56 and CD57), beta-2-microglobulin and keratin. One patient showed a complete response to treatment and two a partial response. Tumor size was significantly smaller after therapy. Clinical and pathological regression were more prominent in the smaller tumors. Numerous macrophages, both mononucleated and multinucleated, were present along the tumor-stroma interface in the posttreatment specimens of seven patients, most prominently in the three patients with tumor regression. The increase in the number of CD68+ and S-100+ macrophages after treatment was statistically significant. Lymphocytic infiltrates, which showed some increase following treatment, were composed of a mixture of T and B lymphocytes, the former mostly in contact with the tumor and the latter placed more peripherally. CD8+ lymphocytes extended into the tumors, whereas CD4+ lymphocytes showed minimal extension. Intensity of beta-2-microglobulin staining in tumors was significantly higher following therapy and associated with a better outcome. The marked increase in macrophages following treatment may indicate that the macrophage plays a major role in tumor recognition, destruction and clearance. An increase in the number of macrophages in a posttreatment specimen may indicate immunoresponsiveness.

Differential expression of proliferation- and apoptosis-related markers in lentigo maligna and solar keratosis keratinocytes.

Keratinocytes influence the number, morphology, and proliferation of melanocytes. An interference in the melanocyte-keratinocyte relationship may contribute to melanoma development. This study examined the expression of apoptotic and proliferative markers in keratinocytes in lentigo maligna to characterize the epidermis permissive to these lesions. Formalin-fixed and paraffin-embedded tissues from 25 samples of lentigo maligna, 20 samples of solar keratoses, and 5 samples each of normal sun-exposed and non-sun-exposed skin (controls) were immunostained with antibodies directed against the proapoptotic markers bax and p53, the antiapoptotic marker bcl-2, and the proliferation marker ki-67. Eight percent of the lentigo maligna samples were positive for keratinocyte expression of bcl-2, 24% were positive for p53, and 76% were positive for bax; respective findings for solar keratoses were 35%, 85%, and 90%. Comparison with normal sun-exposed skin yielded lower rates of keratinocyte proliferation in 56% of the lentigo maligna samples, similar rates in 36%, and higher rates in 8%; for solar keratoses, proliferation was higher than controls in 60% of samples, similar in 35%, and lower in 5%. All these differences were statistically significant. These findings indicate that there are variable patterns of epidermal reaction to chronic sun exposure. The epidermis in lentigo maligna shows overall low proliferation and an apparently low apoptotic tendency. The dysfunctional epidermis may be permissive to aberrant melanocyte proliferation in the early stages of melanoma development.

Possible direct cytoxicity effects of cyclophosphamide on cultured human follicles: an electron microscopy study.

PURPOSE: To evaluate the direct effect of cyclophosphamide on cultured human ovarian follicles. METHODS: Human ovarian cortical slices from premenopausal women were incubated with medium containing cyclophosphamide (0.0005-0.5 mg/mL) for 2-48 h and assessed by transmission electron microscopy. Noncultured specimens and samples cultured without cyclophosphamide were used as controls. RESULTS: There were significantly more damaged granulosa cell nuclei after incubation with 0.5 mg/mL cyclophosphamide for at least 4 h. There were also more changes in the basement membrane after incubation with cyclophosphamide at concentrations of 0.05 and 0.5 mg/mL. CONCLUSIONS: Although the cyclophosphamide dose that caused damage to the granulosa cell nuclei was above the pharmacological level, our results suggest that cyclophosphamide, and not only its active metabolite phospharamide mustard, might have a destructive effect on human follicles, as it remains in the circulation longer. This effect could be mediated by damage to the granulosa cells and perhaps the basement membrane.

p73 overexpression and nuclear accumulation in hepatitis C virus-associated hepatocellular carcinoma.

p73 is the first identified homolog of p53, but its function has not been established. Our study investigated the expression of p73 in liver tissue of patients with hepatitis C virus (HCV)-associated hepatocellular carcinoma (HCC). RT-PCR was performed on RNA extracted from tumorous and nontumorous liver tissue of HCV-associated HCC, and control tissue and the cDNA were sequenced. Anti-p73 polyclonal antibodies were used for protein analysis and immunohistochemistry, and patients' sera were analyzed for anti-p73 antibodies by radioimmunoassay. Analysis of the p53 gene was performed by SSCP and RFLP-PCR. The p73 mRNA and protein were highly expressed and accumulated in HCC tissues. Immunohistochemical studies revealed significant immunoreactivity in the nuclei of HCC cells. No mutations were detected in the p73 gene or in p53, and no loss of heterozygosity of the p53 gene was found. Anti-p73 antibodies were detected in sera of HCC patients, but were not significantly different from that occurring in non-HCV or non-HCC patients. In conclusion, p73 protein is overexpressed and accumulates in the nuclei of HCV-associated HCCs and may play a role in HCC development.

Lack of HER-2/neu expression in Hodgkin and non-Hodgkin lymphoma.

OBJECTIVE: Overexpression of HER-2/neu oncoprotein, a tyrosine kinase receptor, occurs in a variety of human cancers and has been shown to play a critical role in their development. This overexpression is usually associated with poor clinical outcome. The significance of HER-2/neu in lymphomas is unknown. The aim of this study was to evaluate the expression of HER-2/neu in the malignant lymphomas: non-Hodgkin and Hodgkin lymphomas. METHODS: We studied formalin-fixed, paraffin-embedded tissue from 50 patients with lymphoma. Forty-two specimens were from patients with various types of non-Hodgkin lymphoma, and 8 were from patients with Hodgkin lymphoma. HER-2/neu expression was examined by an immunohistochemical technique using the HercepTest. RESULTS: None of the specimens demonstrated overexpression or even any expression of HER-2/neu. Reactive plasma cells showed cytoplasmic staining, which was not found in malignant plasma cells from patients with multiple myeloma. CONCLUSIONS: Non-Hodgkin and Hodgkin lymphomas do not express the HER-2/neu oncoprotein. This finding suggests that HER-2/neu does not play a role in these diseases.

Relationship of tumorigenic malignant melanomas to dermal elastin: an expression of tumor/stromal interaction that may be related to prognosis.

Malignant melanomas, which produce a large number of substances active in connective tissue modulation, must contend with the dermis to grow and propagate. We studied the morphologic interactions between tumorigenic malignant melanomas and dermal elastin. Formalin-fixed and paraffin-embedded tissues of 108 tumorigenic malignant melanomas were stained for elastic tissue with the Verhoeff-van Gieson method. Various aspects of the relationship between malignant melanoma and dermal elastin were analyzed in relation to the histologic and clinical data using univariate and multivariate analyses. Tumor thickness, mitotic rate, and the presence of elastin remnants within the tumors were found to be independent negative prognostic factors, the latter with borderline significance. Tumors with more remnants of elastin were associated with higher stage of disease and lymph node and distant metastases. Tumor infiltration between the elastic fibers in the tumor depth was associated with high Clark level, greater tumor thickness, high stage of disease, and lymph node metastases. At least partial preservation of elastic fibers in the tumor depth was a relatively good prognostic factor whereas complete absence of elastin was an adverse factor. Focal or multifocal absence of elastin in the midst of the tumors or in their depth was usually associated with lymphocytic infiltrates. We suggest that tumors with remnants of elastic fibers and/or invasion between elastic fibers in their depth may be fast growing and highly invasive. The absence of elastin within tumors and at their advancing edge may be related to the elaboration of elastin-degrading substances by melanoma cells or various inflammatory cells. Our findings indicate that the relationship between malignant melanomas and dermal connective tissue components, specifically elastin, may have prognostic significance.