Role of the double-contrast barium enema in rectal stenosis due to suppositories containing paracetamol and acetylsalicylic acid

Self-treatment of chronic headache with suppositories containing paracetamol and acetylsalicylic acid may lead to serious complications. We report the radiological features of five cases of rectal stenosis following the use of such suppositories. The role of the double-contrast barium enema in suggesting the diagnosis of this complication of a chronic and often unrecognized self-treatment is emphasized.

Late liver metastases of small bowel leiomyoma. The difficulty in assessing malignancy in gastro-intestinal smooth muscle tumours

Two cases of small bowel tumour, resected and considered as benign leiomyomas, are reported. Both developed late hepatic metastases, 6 and 8 years after surgery respectively, diagnosed as leiomyosarcoma. Emphasizing the difficulties in assessing malignancy of these tumours and considering local and far dissemination, a long-term follow-up is recommended after surgical resection.

Expression of transforming growth factor beta receptors in normal human colon and sporadic adenocarcinomas

BACKGROUND & AIMS

An absence or a presence of mutated transforming growth factor (TGF)-beta receptors is a possible hypothesis explaining the resistance of cancer cells to the growth-inhibitory effect of TGF-beta. Mutations involving microsatellite-like regions of the type II TGF-beta receptor have been described in subgroups of colorectal cancers. The aim of this study was to investigate the expression and distribution of TGF-beta receptors in sporadic colorectal cancers and normal tissues.

METHODS

Thirty-three sporadic colorectal cancers and 20 normal colonic tissues were explored by immunohistochemistry for the expression of type I and type II TGF-beta receptors. Eighteen tumor and 20 normal samples were used for radioactive thermocycling and sequencing of the two microsatellite-like regions of the type II receptor.

RESULTS

Both receptors were overexpressed in tumors compared with normal samples. There was a relationship between the abundance of type II receptor expression and the degree of differentiation of the tumors but not the Dukes' staging or the localization of the neoplasias. No mutation was observed in the microsatellite-like regions of receptor II in any of the samples.

CONCLUSIONS

Sporadic colorectal cancers do not show an absence or a presence of mutated TGF-beta receptors that could explain a resistance to TGF-beta-mediated growth inhibition. The pathways to tumorigenesis of sporadic colorectal cancers may be different from those of some hereditary ones.

[Cap polyposis: a rare syndrome]

We report a case of inflammatory cap polyposis of the colon, a rare syndrome, affecting the rectosigmoid. It was observed in a context of mucous diarrhea. Endoscopic and radiological features consisted of elevated and umbilicated nodular lesions. Histology revealed polypoid lesions containing elongated crypts with superficial abrasions, covered by inflammatory and fibrinoid material. Etiopathogenesis of this new syndrome is unknown.

Oral budesonide for lymphocytic colitis

Lymphocytic colitis is a rare inflammatory colonic disease of unknown etiology accompanied by watery diarrhea. Diagnosis is based upon pathological examination of colonic biopsies. Treatment essentially involves antiinflammatory agents such as sulfasalazine/5-ASA or corticosteroids if necessary. We report the case of a female patient suffering from severe lymphocytic colitis who remained unresponsive after 5-ASA therapy but who improved dramatically after oral budesonide administration.

Percutaneous transperineal radiofrequency ablation of prostate tumour: safety, feasibility and pathological effects on human prostate cancer

OBJECTIVE

To evaluate the safety of radiofrequency (RF) energy delivered interstitially in patients with prostate cancer scheduled for radical prostatectomy and to correlate the proposed theoretical lesion size with the pathological findings.

PATIENTS AND METHODS

Radiofrequency interstitial tumour ablation (RITA) was performed in 15 patients with localized prostate cancer before radical surgery. RF energy was delivered to the prostate by active needle electrodes (monopolar or bipolar) placed transperineally under transrectal ultrasonography guidance. Needle electrodes were used with different configurations and in some cases were covered by retractable shields to vary the length and circumference of the thermal lesions created. In eight patients, the procedure was performed immediately before radical prostatectomy, in six RITA was performed under spinal anaesthesia 1 week before surgery and in one patient, no surgery was performed but the patient was followed by serial determinations of prostate specific antigen (PSA). At least two lesions were created in each prostate, including both capsule and peripheral zones. NADPH and haematoxylin & eosin (H&E) staining were used to assess the extent of the necrotic lesion in the radical prostatectomy specimen.

RESULTS

The mean energy delivered was 10.5 kJ, with central temperatures reaching up to 105 degrees C during 12 min of ablation; rectal temperature remained at < 38 degrees C. There were no complications. Macroscopic examination showed well-demarcated lesions including the prostatic capsule, up to 2.2 x 1.5 x 4.5 cm. With monopolar energy, the observed lesion size was comparable to the predicted 2 x 2 x 2 cm lesion, while with bipolar energy, lesion size was related to interneedle distance and uncovered needle length. Microscopic examination showed clearly delineated lesions both with NADPH (in prostates immediately removed after surgery) and H&E (at 1 week after RITA) staining. The lesion size observed on pathological analysis correlated with the predicted lesion size. In one patient, no residual cancer was found in the specimen. In the patient whose entire prostate was targeted and followed by serial PSA measurements, the latter were undetectable at 3 months of follow-up.

CONCLUSION

Transperineally delivered RF energy is capable of safely creating extensive coagulative necrotic lesions in prostate cancer tissue, in a reproducible and controlled manner. The results presented here provide basic information for the potential future application of this form of energy for localized prostate cancer.

Fetal endocardial fibroelastosis: ultrasonographic findings in two cases

EFE is a rare cardiac disorder with poor prognosis and uncertain cause. Primary and secondary forms have been described. Most authors consider that all EFE is secondary--a reactive process set off in the endocardium by stress on the myocardium. We report two cases representing the primary dilated form and the secondary contracted form. The dilated form was associated with intracavitary thrombus of the left ventricle. In both cases, an unusual presence of subendocardial calcifications was noted. The ultrasonographic findings are discussed.

Effects of nitric oxide on blood flow distribution and O2 extraction capabilities during endotoxic shock

The effects of the nitric oxide (NO) synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) and the NO donor 3-morpholinosydnonimine (SIN-1) were tested in 18 endotoxic dogs. L-NMMA infusion (10 mg . kg-1 . h-1) increased arterial and pulmonary artery pressures and systemic and pulmonary vascular resistances but decreased cardiac index, left ventricular stroke work index, and blood flow to the hepatic, portal, mesenteric, and renal beds. SIN-1 infusion (2 microg . kg-1 . min-1) increased cardiac index; left ventricular stroke work index; and hepatic, portal, and mesenteric blood flow. It did not significantly influence arterial and pulmonary artery pressures but decreased renal blood flow. The critical O2 delivery was similar in the L-NMMA group and in the control group (13.3 +/- 1.6 vs. 12.8 +/- 3.3 ml . kg-1 . min-1) but lower in the SIN-1 group (9.1 +/- 1.8 ml . kg-1 . min-1, both P < 0.05). The critical O2 extraction ratio was also higher in the SIN-1 group than in the other groups (58.7 +/- 10.6 vs. 42.2 +/- 7.6% in controls, P < 0.05; 43.0 +/- 15.5% in L-NMMA group, P = not significant). We conclude that NO is not implicated in the alterations in O2 extraction capabilities observed early after endotoxin administration.

Radiofrequency interstitial tumor ablation (RITA) is a possible new modality for treatment of renal cancer: ex vivo and in vivo experience

Small renal tumors are increasingly diagnosed and are frequently treated by nephron-sparing surgery. Tumors can be ablated by radiofrequency (RF) energy, which allows the operator to create very localized necrotic lesions. Radiofrequency interstitial tumor ablation (RITA) has been used in human kidneys in an ex vivo experiment to assess the necrotic lesions produced in a model close to physiologic conditions and then in three patients with localized renal cancer prior to radical nephrectomy. In the ex vivo model, four freshly removed kidneys were treated. Bipolar RF energy was delivered by a generator connected to two needles introduced parallel to each other into the renal parenchyma. A thermocouple was inserted between the two active electrodes. The renal artery at physiologic conditions was maintained at a constant temperature of perfusion of 37 degrees C by a computer-assisted Hot-line monitor. Two lesions were produced in each pole of each kidney including the cortex and the medulla. In an initial human study focusing on safety, feasibility, and pathology, three patients were treated by RITA with bipolar and monopolar energy. One patient with a peripheral 2-cm upper-pole tumor was treated percutaneously under ultrasound guidance with local anesthesia only 1 week prior to surgery. The other patients, with 3- and 5-cm tumors, were treated during surgery under general anesthesia just before nephrectomy. Ex vivo, the maximum temperature at the active needles ranged from 84 degrees C to 130 degrees C with 10 to 14 W applied during 10 to 14 minutes. Lesions were on average 2.2 x 3 x 2.5 cm.3 Microscopic examination showed stromal edema with intensive pyknosis. No damage was seen to adjacent untreated tissue. In the in vivo procedure, tolerance of RTA as an anesthesia-free procedure was excellent. The size of the observed lesions was comparable to the forecast size depending on the needle deployment. No side effects were noted, and no adjacent structures were affected by the RF ablation. These preliminary studies demonstrate the ability of RITA to produce localized extensive necrosis in kidney parenchyma and tumors safely under local anesthesia. Further studies could evaluate this new minimally invasive treatment in small kidney tumors considered for nephron-sparing surgery.

Increased transaminases in psychiatry: a case report

We report the case of a patient admitted to the hospital with psychiatric troubles. Soon after admission, he presented severe hepatitis of unknown origin. Careful review of the charts, transvenous liver biopsy, right heart and hepatic pressure measurements, negative toxicologic and viral screenings were highly suggestive of hypoxic hepatitis. Indeed, the patient had previously been treated for a decompensated cardiomyopathy and medications stopped prior to the current admission. Without clear clinical evidence of heart failure he presented a brief malaise two days before the increase in liver enzymes. Holter heart recording showed afterwards bouts of ventricular tachycardia. Treatment with Dobutamine and antiarrythmics led to a rapid decrease of transaminase levels and recovery in liver function. Unfortunately, he died three weeks later from his cardiomyopathy. This case illustrates the need for cardiovascular work-up in the context of hepatitis from unknown origin.

Production and role of interleukin-10 in concanavalin A-induced hepatitis in mice

Experimental T-cell-mediated hepatitis induced by concanavalin A (Con A) involves the production of proinflammatory cytokines. Because interleukin (IL)-10 is a potent anti-inflammatory cytokine derived from macrophages and T cells and is produced within the liver, we investigated the role of IL-10 in modulating the hepatotoxicity and the secretion of cytokines following in vivo injection of Con A. IL-10 is produced early in the serum after Con A challenge. Neutralization of endogenous IL-10 by monoclonal antibodies (mAbs) increases the secretion of tumor necrosis factor alpha (TNF-alpha) (+111%), interferon gamma (IFN-gamma) (+92%), and IL-12 (+730%) 8 hours after Con A injection, and increases the hepatotoxicity, assessed by serum alanine transaminase (ALT) (+174%) measurement and by histology, 24 hours after induction of hepatitis. Conversely, preadministration of recombinant IL-10 reduces the production of these proinflammatory cytokines (-47%, -80%, and -47% for TNF-alpha, IL-12, and IFN-gamma, respectively), and decreases neutrophil infiltration and ALT serum concentration (-74%) 8 hours after Con A challenge. We conclude that IL-10, either endogenously produced or exogenously added, has a hepatoprotective role in Con A-induced hepatitis, through its suppressive property on proinflammatory cytokine production, and that it might be of therapeutic relevance in human liver diseases involving activated T cells.

Possible mechanisms of action of transurethral needle ablation of the prostate on benign prostatic hyperplasia symptoms: a neurohistochemical study

PURPOSE

Transurethral needle ablation of benign prostatic hypertrophy (BPH) is a rapid, anesthesia-free outpatient procedure using low level radiofrequency energy that produces coagulative necrosis lesions at temperatures of approximately 100C. Clinically, significant improvement in objective and subjective parameters has been observed in BPH patients. Transurethral needle ablation has also been shown to be effective in relieving urinary retention. However, the precise mechanism of action of this procedure remains to be clarified. Ablation could produce its action on the dynamic component of the infravesical outlet obstruction. We analyzed the possible effects of transurethral needle ablation on the intraprostatic innervation.

MATERIALS AND METHODS

Histological sections from 10 open prostatectomy specimens (BPH) recovered 1 to 46 days after transurethral needle ablation were stained with hematoxylin and eosin and an immunohistochemical technique, using antibodies against S100 proteins and nonspecific enolase as specific nerve markers, and against anti-prostate specific antigen and anti-desmin for glandular and muscle cells, respectively. We used 5 BPH specimens as controls.

RESULTS

Microscopic examination of the treated areas showed necrotic lesions affecting epithelial and smooth muscle cells in the transition zone at a depth of 0.3 to 1.0 cm, from the preserved urethra. Nerve fibers in the control specimens and untreated prostatic areas were predominant in the urethral submucosal layer and in the stroma surrounding the epithelial nodules. No staining of any axon or isolated nerve cell was observed in any specimen treated by transurethral needle ablation, and there was a sharp and clear delineation between treated and untreated areas.

CONCLUSIONS

Our study demonstrated severe thermal damage to intraprostatic nerve fibers caused by transurethral needle ablation. A long-term denervation of alpha-receptors and/or sensory nerves could explain the clinical effects of transurethral needle ablation of the prostate. Theoretically, the best location to produce necrotic lesions should include submucosal and subcapsular nerve endings. Differences in the distribution of the adrenoreceptors and morphometry of the prostate transition zone could partly explain differences in clinical outcome observed after transurethral needle ablation of the prostate.

Hepatoprotective role of interleukin 10 in galactosamine/lipopolysaccharide mouse liver injury

BACKGROUND & AIMS

Interleukin (IL)-10 is a potent anti-inflammatory cytokine. Its role in modulating liver injury induced by galactosamine and lipopolysaccharide (Gal/LPS) was investigated.

METHODS

The effects of recombinant IL-10 (rIL-10), anti-IL-10 monoclonal antibodies, or gadolinium chloride (GdCl3) pretreatment were studied in mice challenged with Gal/LPS. Tumor necrosis factor (TNF) alpha and IL-10 serum concentrations were measured and liver injury was assessed by alanine aminotransferase (ALT) serum concentrations and by histology.

RESULTS

(1) IL-10 is produced early and together with TNF-alpha after Gal/LPS challenge. (2) Anti-IL-10 pretreatment increases TNF-alpha (+443%, P = 0.04), ALT (+160%, P = 0.04) serum levels, and the percentage of severe necrosis compared with control monoclonal antibodies. (3) Administration of rIL-10 30 minutes before Gal/LPS decreases TNF-alpha (-67%, P = 0.02), ALT (-94%, P = 0.01) serum concentrations, and the proportion of severe necrosis. The hepatoprotective effect is still observed when rIL-10 is injected 30 or 120 minutes after Gal/LPS. (4) GdCl3 pretreatment protects against hepatotoxicity, decreases TNF-alpha, but increases IL-10 serum concentrations.

CONCLUSIONS

These results indicate that IL-10 protects the liver in the Gal/LPS mouse model. Increased IL-10 and decreased TNF-alpha secretion are potentially involved in the hepatoprotection observed after GdCl3 pretreatment.

Localization of transforming growth factor-beta 1 precursor and latent TGF-beta 1 binding protein in colorectal adenomas

Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional cytokine and is thought to be involved in colorectal tumorigenesis as a regulator of cell growth and differentiation. This role is mainly supported by in vitro studies while its role in vivo remains unclear. The aim of the present study was to investigate whether the TGF-beta 1 precursor (beta 1-LAP) and the latent TGF-beta 1 binding protein (LTBP) are expressed in colorectal adenomas, the presumed precursors of most of colorectal adenocarcinomas. TGF-beta 1 precursor and LTBP were examined in 35 adenomas and 10 normal colonic mucosa specimens by immunohistochemistry, using specific polyclonal antibodies. In normal colonic mucosa, beta 1-LAP was moderately expressed in epithelial crypt cells and in the stromal cells in the lamina propria. In adenomas, beta 1-LAP was localized in epithelial cells with an heterogeneous pattern and was also present in stromal cells around the adenomatous glands. LTBP was not detected in epithelial cells but was observed in stromal cells and in the extracellular matrix (ECM). beta 1-LAP expression in epithelial cells did not correlate with the grade of dysplasia, while LTBP localized in stromal cells and ECM appeared to be closely associated with areas of higher grade of dysplasia. This study is the first demonstration of both beta 1-LAP and LTBP in colorectal adenomas with different dysplasia grades. Our results suggest that TGF-beta 1 might be involved in the mechanisms controlling in vivo colorectal tumorigenesis and support a role for the stromal-associated TGF-beta 1.

[A new method of cancer treatment: the use of radiofrequencies in urological tumors]

This study reports our preliminary experience with interstitial radiofrequencies in the treatment of urological malignancies. Bipolar radiofrequency was interstitially delivered in four freshly removed human kidneys in an ex-vivo model. The kidney was perfused ex-vivo with 37 degrees C saline in order to mimic physiological conditions. Large reproducible and controlled lesions (hypereosinophilia and pyknosis) were observed in the parenchyma between the active needles. Further animal and human clinical studies are planned to precise the place of bipolar RF in the treatment or urological malignancies, and especially in kidney tumors.

Transurethral needle ablation of the prostate: clinical experience in patients in urinary acute retention

OBJECTIVE

To evaluate the clinical outcome of patients in urinary retention due to benign prostatic enlargement (BPE) treated using transurethral needle ablation (TUNA), an outpatient procedure requiring only local intra-urethral anaesthesia and intravenous sedoanalgesia.

PATIENTS AND METHODS

The TUNA technique was used in 38 patients in acute retention due to BPE, 34 of whom were a poor surgical risk. A special cytoscopic catheter device delivered low-level radiofrequency (RF) energy interstitially to a localized area of the prostate, producing necrotic lesions within the prostatic parenchyma. After treatment, all men were evaluated using urinary flow rates, residual urine volume, the International Prostate Symptom Score and quality of life score at 1, 3 and 6 months.

RESULTS

The mean prostate size was 43.1 g (range 18-90). Tolerance of the procedure when using topical anaesthetic and intravenous sedation was excellent. Of the 38 patients treated using TUNA, 30 (79%) resumed voiding within a mean of 8.7 days (range 2-27). After 6 months, the sustained mean peak flow rate was 10.4 +/- 3.4 mL/s and the mean residual volume was 76 +/- 45 mL. Five of the patients who did not resume voiding after TUNA underwent retropubic prostatectomy and one patient underwent TURP. The mean prostate size in these patients was 55.7 g. Failure to void was associated with the treatment of too few areas of the prostate for its volume.

CONCLUSION

This study demonstrated that TUNA is highly effective in relieving patients in urinary retention due to BPE and seems particularly suitable for treating patients who are at greater risk during surgery.

p53 Protein overexpression in verrucous carcinoma of the skin

BACKGROUND

Verrucous carcinoma is a rare variant of well-differentiated squamous cell carcinoma which is characterized by a marked local aggressivity and a poor metastatic potential. Until now, little has been known about the oncogenic mechanisms of this tumor. Recently, extensive investigations have shown that p53 protein, a nuclear protein with oncogene-suppressing activity, may play a crucial role in cell transformation and immunoreactivity for this protein is found in a wide variety of cancers.

OBJECTIVE AND METHODS

The aim of the present study is to examine the frequency of immunohistochemically detectable p53 protein by using two monoclonal antibodies (D07 and BP53-12) in 8 cases of formalin-fixed and paraffin-embedded specimens of verrucous skin carcinoma.

RESULTS

Overexpression of p53 protein was detected in 6 (75%) of the cases examined with the D07 antibody and in 5 (62.5%) cases with BP53-12. The p53 positivity was shown in a peripheral distribution affecting mainly the basal cell layers of tumoral islands.

CONCLUSION

In a high percentage of verrucous carcinoma, p53 immunoreactivity has not been previously described in the literature and our findings suggest that abnormal expression of p53 tumor suppressor protein is a common event in the pathogenesis of this tumor.

Proliferating cell nuclear antigen distribution in verrucous carcinoma of the skin

Verrucous carcinoma (VC) of the skin is a rare variety of well-differentiated squamous cell carcinoma (SCC) characterized by aggressive local growth and a low metastatic potential. These tumours are known to have histological and virological features similar to classic warts or condylomata. The aim of the present study was to map the proliferative compartment in VC (n = 7) in comparison with warts (n = 10) and typical well-differentiated SCC (n = 10). The proliferating cells were detected by immunostaining of proliferating cell nuclear antigen (PCNA) in formalin-fixed, paraffin-embedded tissue sections, using the commercially available anti-PCNA monoclonal antibody PC10. Normal epidermis served as a positive control and reference. In VC and warts, the PCNA-positive cells were principally located at the periphery of lesions, in the basal layer of the tumour islands. In some warts, however, stronger PCNA expressed was noted in the superficial layers, of the lesions corresponding to virus-infected keratinocytes (koilocytotic cells). In contrast, in SCC, PCNA-positive cells were randomly scattered throughout the tumours. Our findings suggest that, on the basis of mapping of PCNA distribution, VC resembles large warts or condylomata rather than typical SCC. Thus, VC appears to be a distinct clinical entity, intermediate between these two types of lesions, not only because of its clinical entity, intermediate between these two types of lesions, not only because of its clinical and virological features, but also with regard to its proliferative organization.

Adenocarcinoma of the ileum. A case report, and review of the literature

A 47-year-old female presented with intestinal occlusion and a lower abdominal mass. On laparotomy, a 10 cm diameter mass was discovered involving the ileum, jejunum, vagina and the bladder. Pathological studies conclusion was a primary adenocarcinoma of the ileum involving the jejunum. Small bowel carcinoma is rare. It occurs between sixty- and seventy-year-old equally in male and female. It presents most frequently in the duodenum, sometimes in the jejunum, and occasionally in the ileum. The symptoms are not specific and do not point to the diagnosis which must be made radiologically and endoscopically. Currently, for a minority of patients, surgical resection remains the only hope of cure. Palliative resections and bypass procedures can prevent occlusion or subocclusion.

Transitional cell carcinoma of the bladder: evaluation of the role of human papillomaviruses

OBJECTIVES

The study evaluated the conflicting results of the role of human papillomavirus (HPV) in the development of bladder carcinoma.

METHODS

We analyzed the frequency of HPV types 6, 11, 16, 18, and 33 by using polymerase chain reaction on formalin-fixed, paraffin-embedded specimens, from 75 cases of transitional cell carcinoma (TCC) of the bladder. Fifteen samples of normal urothelium adjacent to TCC (10) or from normal bladder obtained at autopsy (5) served as negative controls.

RESULTS

HPV type 16 deoxyribonucleic acid (DNA) was detected in 2 (2.7%) of the 75 cases of TCC and in none of the normal urinary bladder cases. The 2 patients with HPV type 16 were immunosuppressed after undergoing renal and cardiac transplantation.

CONCLUSIONS

These results strongly suggest that HPVs play a minor role in the development of TCC of the bladder in the general population, although they can act as oncogenic agents in predisposed patients, such as those who are immunosuppressed.

Human papillomavirus type 16 associated with multifocal transitional cell carcinomas of the bladder in two transplanted patients

This report describes two cases of rapidly progressive, multifocal transitional cell carcinomas of the bladder that developed in two patients after renal and cardiac transplantation, respectively. In both cases human papillomavirus (HPV) type 16 DNA was detected using the polymerase chain reaction DNA amplification method. To our knowledge, this HPV type has not been previously described in multifocal bladder transitional cell carcinoma in transplanted patients. Our findings suggest that HPV may play a major role in the development of rapidly progressive, multifocal transitional cell carcinoma in immunosuppressed patients.

Two cases of water-melon stomach and a review of the literature

We report two cases of "water-melon stomach", which is a peculiar form of gastric antral vascular ectasia, characterized by a specific and striking endoscopic aspect. It is observed in a context of chronic iron deficiency anemia and gastrointestinal blood loss, particularly in elderly female patients. The clinical endoscopic, histologic, pathogenic and therapeutic aspects are described, with review of the literature.

Transformation of common warts into squamous cell carcinoma on sun-exposed areas in an immunosuppressed patient

We report one case of renal transplant recipient who developed widespread multiple verrucous skin lesions. Histologic examination revealed typical warts and, only from several sites exposed to sun (hands and face), a development of dysplasia within the warts and a transformation of some of them toward infiltrating squamous cell carcinoma (SCC). Human papillomavirus (HPV) testing for DNA by polymerase chain reaction DNA amplification identified HPV type 1 in both warts and SCC. Our findings suggest that classic warts may progress to high-grade lesions and that, in addition to the oncogenic potential of the virus alone, other factors including the host's immunosuppressed state and ultraviolet radiation seem to be essential to malignant transformation.