The prognostic impact of the ubiquitin ligase subunits Skp2 and Cks1 in colorectal carcinoma

BACKGROUND

Loss of the cell-cycle inhibitory protein p27Kip1 is associated with poor prognosis in colorectal carcinoma. The decrease in p27Kip1 levels is the result of increased proteasome-dependent degradation, mediated and rate-limited by its specific ubiquitin ligase subunits S-phase kinase protein (Skp) 2 and cyclin-dependent kinase subunit (Cks) 1. Recently, Skp2 and Cks1 expression were found to be increased in some colorectal carcinomas, but their potential role as prognostic markers for survival is unknown. The present study was undertaken to assess the prognostic value of both Skp2 and Cks1 in colorectal carcinoma.

MATERIALS AND METHODS

The expression of Skp2, Cks1, and p27Kip1 was examined by immunohistochemistry using highly specific antibodies on formalin-fixed, paraffin-embedded tissue sections from 80 patients with colorectal carcinoma.

RESULTS

Overexpression of Skp2 and Cks1 strongly correlated with loss of p27Kip1 and loss of tumor differentiation. A significant decrease in overall survival was observed in patients expressing high Skp2 or Cks1 levels, and in particular, patients with Stage II and III disease. Each protein provided significant additional prognostic information to that given by disease stage, tumor grade, or p27Kip1 expression.

CONCLUSIONS

Results suggest that overexpression of Skp2 or Cks1 is strongly associated with poor prognosis and may thus be used as prognostic markers for overall survival in colorectal carcinoma.

The alopecias associated with vitamin D-dependent rickets type IIA and with hairless gene mutations: a comparative clinical, histologic, and immunohistochemical study

OBJECTIVE

To establish the unique and common clinical and microscopic characteristics of the alopecias associated with vitamin D-dependent rickets (VDDR) type IIA and with hairless gene mutations.

DESIGN

A comparative clinical, histologic, and immunohistochemical study of the alopecias in 6 patients with VDDR IIA and 4 patients with atrichia with papular lesions (APL) and/or alopecia universalis congenita (AUC) (hereinafter "APL/AUC").

MAIN OUTCOME MEASURES

Clinical data were gathered from medical records, personal interviews, and physical examinations. Histologic and immunohistochemical studies were performed on 6 scalp punch biopsy specimens from each of the 2 studied groups.

RESULTS

The alopecias in VDDR IIA and APL/AUC showed similar clinical, histologic, and immunohistochemical features. The clinical presentation of the VDDR alopecia resembled either the APL phenotype (ie, with papules and milia) or the AUC phenotype (without papules and milia). The main histologic findings included void infundibula; absence of the lower two thirds of the hair follicles, often replaced by vertically oriented irregular epithelial structures or epithelial cysts; irregular epithelial structures, often with small cysts in the middle and lower dermis; and small, medium, and large keratinizing cysts at all levels of the dermis. The larger epithelial cysts in the upper dermis stained positively for cytokeratin (CK) 10, which suggests an infundibular derivation, whereas the remaining irregular epithelial structures and cysts in the middle and lower dermis stained positively most frequently for CK17, CK19, and CD34, which suggests an outer root sheath derivation.

CONCLUSIONS

The alopecias associated with VDDR IIA and with hairless gene mutations show striking clinical and microscopic similarities. Disintegration of the lower two thirds of the hair follicles seems to be the underlying defect, and a common pathogenetic pathway might be involved.

Decreased level of the cell cycle regulator p27 and increased level of its ubiquitin ligase Skp2 in endometrial carcinoma but not in normal secretory or in hyperstimulated endometrium

p27 is a cyclin-dependent kinase (CDK) inhibitor whose specific late G(1) destruction allows progression of the cell across the G(1)/S boundary. The protein is ubiquitinated by S-phase kinase-interacting protein-2 (Skp2) following its specific phosphorylation, and is subsequently degraded by the 26s proteasome. There is a direct relationship between low level of p27 and rapid proliferation occurring in several benign states and in many malignancies. In the glandular cells of the normal endometrium, the level of p27 is exceedingly low during the proliferative phase, whereas it is markedly increased during the secretory phase. The expression of p27 in endometrial carcinoma is very low but has been found to increase following treatment with progesterone. However, estrogen exposure is considered as a major risk factor in developing endometrial cancer. The implications of the high dose of estrogen and progesterone induced during IVF treatment are still unknown. We have examined the expression of p27 and Skp2 as well as of Ki67 proliferation marker by using endometrial extracts and cells from normal endometrium, from ovarian hyperstimulated patients, and from endometrial carcinoma patients. The expression of p27, Skp2 and Ki67 was found to be similar in both normal secretory endometrium and endometrium from ovarian hyperstimulated patients. In striking contrast, p27 is significantly lower while Skp2 and Ki67 are significantly higher in the endometrial carcinoma and in endometrium from the proliferative phase compared with their normal secretory counterpart tissue.

Expression of HER2 and C-KIT in nasopharyngeal carcinoma: implications for a new therapeutic approach

We sought to determine the expression and prognostic significance of HER2 and c-KIT proteins in nasopharyngeal carcinoma (NPC). In this retrospective study, immunohistochemical stains for HER2 and c-KIT were performed on formalin-fixed paraffin-embedded sections from 49 patients with NPC who were treated at our hospital from 1971 to 2000. The clinical and immunohistochemical data were correlated, including gender, ethnic origin, age, histological type, EBV status (EBER in situ hybridization), stage, and overall survival. HER2 expression was not found in the tested samples. C-KIT overexpression was found in 33% (16/49) of the patients. Nine of the 16 samples (56%) were strongly positive for c-KIT protein (staining of >50% of the tumor cells). C-KIT expression was associated with younger age. C-KIT was not found in patients with squamous carcinoma or in those with negative EBV status, although these two groups consisted of only five patients each. Although c-KIT-positive cases tended to be associated with slightly better survival, this was not statistically significant. C-KIT protein was expressed in one third of the NPC patients in this study, only in EBV-positive, undifferentiated, or nonkeratinizing carcinoma patients. Further study is needed to check whether c-KIT expression is correlated with c-KIT DNA mutations and to test the possibility of treatment with imatinib mesylate (Gleevec). HER2 protein was negative in the same tested specimens.

Alterations in the expression of the cell cycle regulatory protein cyclin kinase subunit 1 in colorectal carcinoma

BACKGROUND

Low levels of p27(Kip1) are associated with high aggressiveness and poor prognosis in various malignancies, including colorectal carcinoma. The authors showed that S phase kinase protein 2 (Skp2), the specific ubiquitin ligase subunit that targets p27(Kip1) for degradation, was overexpressed and was inversely related to p27(Kip1) levels in patients with colorectal carcinoma. The essential role of cyclin kinase subunit 1 (Cks1) in Skp2-dependent p27 degradation was recently discovered, but its role in human malignancies is unknown.

METHODS

Quick-frozen colorectal tumor samples from 30 patients were separated by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, transferred to nitrocellulose, and probed with highly specific monoclonal antibodies directed against Cks1, Skp2, and p27(Kip1). The expression of Cks1 was also examined by immunohistochemistry using formalin-fixed, paraffin-embedded tissue sections from the same patients.

RESULTS

A strong correlation was found between Cks1 levels and Skp2 expression and loss of tumor differentiation. A significant inverse relation was also observed between levels of Cks1 and p27(Kip1) and overall survival.

CONCLUSIONS

The results of the current study suggest that increased expression of Cks1 may have an important causative role in decreasing levels of p27 in patients with aggressive colorectal carcinoma.

Human heparanase nuclear localization and enzymatic activity

In previous studies, we have demonstrated that human heparanase (endo-beta-D-glucuronidase) is localized primarily in a perinuclear pattern within lysosomes and late endosomes, and occasionally may be surface associated and secreted. The presence of two potential nuclear localization sequences in human heparanase, led us to investigate heparanase translocation into the nucleus and subsequent degradation of nuclear heparan sulfate. Applying cell fractionation, Western blot analysis, determination of heparanase activity and confocal microscopy, we identified heparanase within the nuclei of human glioma and breast carcinoma cells and estimated its amount to be about 7% of the cytosolic enzyme. Our results indicate that nuclear heparanase colocalizes with nuclear heparan sulfate and is enzymaticaly active. Moreover, following uptake of latent 65 kDa heparanase by cells that do not express the enzyme, an active 50 kDa heparanase was detected in the cell nucleus, capable of degrading both nuclear and extracellular matrix-derived heparan sulfate. Immunohistochemical examination of human squamous cell carcinoma specimens revealed a prominent granular staining of heparanase within the nuclei of the epithelial tumor cells vs no nuclear staining in the adjacent stromal cells. Taken together, it appears that heparanase is translocated into the cell nucleus where it may degrade the nuclear heparan sulfate and thereby affect nuclear functions that are thought to be regulated by heparan sulfate. Nuclear localization of heparanase suggests that the enzyme may fulfill nontraditional functions (ie, regulation of gene expression and signal transduction) apart of its well-documented involvement in cancer metastasis, angiogenesis and inflammation.

Prevalence and relevance of EBV latency in nasopharyngeal carcinoma in Israel

BACKGROUND

Nasopharyngeal carcinoma (NPC) is frequently associated with Epstein-Barr virus (EBV). The incidence of NPC in Western countries is lower than in the Far East, and EBV latency in NPC is less prevalent. Israel, as a part of the Mediterranean area, is one of the countries with an intermediate risk for NPC.

METHODS

Immunohistochemistry (IHC) for latent membrane protein 1 (LMP-1) and in situ hybridisation (ISH) for EBV encoded RNA (EBER) were used to evaluate the prevalence and possible prognostic value of EBV latency among Israeli patients with NPC. Forty five patients with different NPC histologies were studied.

RESULTS

LMP-1 IHC was positive in six samples only, all with undifferentiated histology. EBER ISH was positive in 40 of the 45 samples. According to histological type, three of five patients with squamous cell carcinoma were EBV positive and 37 of 40 non-keratinising and undifferentiated carcinoma cases were positive. Although EBV was more prevalent in patients with non-squamous carcinoma, the difference was not significant, probably because of the small number of patients with keratinising carcinoma. With regard to the clinical categories and survival, no significant difference could be detected between patients who were positive or negative for EBER ISH. No association was found between EBV latency and patient sex, age, origin, stage, or survival.

CONCLUSIONS

NPC in Israel is highly associated with EBV latency as detected by EBER ISH. LMP-1 IHC is considerably less sensitive in detecting EBV latency in NPC among the same patient group.

The Necrotizing Effect of Pulse Cryocycling on Liver Tissue

HYPOTHESIS

Repeated cycles of freezing improve the necrotizing effect of cryosurgery. We investigated whether multiple, very short periods of freezing and thawing (pulse cryocycling) enlarged the area of cell cryonecrosis within the iceball, compared with the standard method of cryocycling.

DESIGN

Liver cryonecrosis was produced in 3 groups of rabbits by means of 2 cycles of 5-minute freezing processes, each followed by 5 minutes of spontaneous thawing. In the control group (group 1), the freezing periods were uninterrupted. In the pulse cryocycling groups, the freezing periods consisted of repeated episodes of freezing and active thawing of 15 seconds (group 2) or 30 seconds (group 3) each. The edges of all lesions were visually marked. The correlation between marking and borders of the cryolesion were examined ultrasonographically. All animals were killed on the following day, and the liver was harvested and examined histologically.

SETTING

Animal experimental laboratory.

RESULTS

Complete liver cell demise was observed up to the edge of the cryolesions in all 3 groups of animals. However, a thin, sharply bounded intermediate zone of incomplete tissue destruction was observed at the border of the cryolesions, which was relatively thicker in group 2.

CONCLUSIONS

In our study, pulse cryocycling had no advantage compared with regular cryocycling, which obtained optimal results in normal liver tissue. However, compared with the 30-second cycles, the 15-second pulse cycling yielded poorer results.

Inverse relationship between Skp2 ubiquitin ligase and the cyclin dependent kinase inhibitor p27Kip1 in prostate cancer

PURPOSE

Prostate carcinomas show a low level of the cell cycle inhibitor p27, which correlates with tumor aggressiveness. In tumors p27 is of the WT species and its deregulation is due to aberrant ubiquitin mediated degradation. The p27 is degraded following phosphorylation and subsequent recognition by SCFSkp2 ubiquitin ligase. We examined the relationship between p27 and its specific ligase Skp2 in normal and malignant prostate tissues. A possible correlation among the levels of these proteins, tumor grading and clinical state was also investigated.

MATERIALS AND METHODS

Using immunohistochemistry immunofluorescence microscopy and Western blot analysis 51 samples from needle biopsies, transurethral resection and radical prostatectomy were analyzed for p27 and Skp2 expression. Correlation with tumor grading (Gleason) was performed. In 22 proven metastatic or organ confined cases correlation was also done with the Ki67 proliferative marker.

RESULTS

Skp2 expression demonstrated a significant and direct correlation with malignancy (p <0.0001). Furthermore, a significant correlation was found between Skp2 level and tumor aggressiveness graded by Gleason score (p <0.0002) and prostate specific antigen. Patients with metastases had significantly higher Skp2 and Ki67 expression than those with organ confined disease (p <0.0001). In addition, Skp2 levels significantly correlated with Ki67 (r = 0.73, p <0.0001). An inverse correlation was found between p27 and Skp2 ligase.

CONCLUSIONS

Skp2 expression in prostate biopsies may be used as an additional marker for tumor aggressiveness. The results also suggest a role for Skp2 in the pathogenesis of prostate malignancy.

Ki67 antigen and PCNA proliferation markers predict survival in anorectal malignant melanoma

AIMS

To find a possible correlation of Ki67 antigen and proliferating cell nuclear antigen (PCNA) with prognosis in anorectal malignant melanoma.

METHODS AND RESULTS

Thirty patients with anorectal malignant melanoma were studied. The percentage of tumour cells stained for Ki67 and PCNA in paraffin sections was assessed. Mode of treatment (local excision or abdominoperineal resection), depth of tumour invasion, attempt at cure as defined by complete tumour excision and absence of distant metastases at presentation, tumour blood vessel invasion, and tumour necrosis, as well as Ki67 and PCNA, were all correlated with survival. By univariate analysis, PCNA, Ki67, attempt at cure, local excision (and not abdominoperineal resection), and depth of invasion were all significantly associated with longer survival. By multivariate analysis, only PCNA was significantly associated with survival, while Ki67 showed a significant positive correlation with PCNA. With a cut-off point of 40%, patients with lower Ki67 scores showed survival advantage over those with higher Ki67 scores (P=0.0004). With a cut-off point of 80%, patients with lower PCNA scores showed survival advantage over those with higher PCNA scores (P=0.0001). The staining for proliferation markers was also associated with depth of tumour invasion.

CONCLUSIONS

Ki67 and PCNA immunostaining in paraffin sections may be useful for the prediction of survival in patients with anorectal malignant melanoma. Larger studies are needed to confirm our results.

MPGN type I induced by granulocyte colony stimulating factor

We report a girl with severe congenital neutropenia who has received long-term granulocyte-colony stimulating factor (G-CSF) therapy and has developed macroscopic hematuria, proteinuria, and decreased renal function associated with biopsy-proven membranoproliferative glomerulonephritis (MPGN) type I. Temporary discontinuation of G-CSF therapy as well as the use of glycosylated G-CSF has resulted in improvement in renal manifestations. We postulate that the MPGN was G-CSF-induced. Long-term G-CSF therapy should be used with great caution and close surveillance of kidney function.

Splenic littoral cell haemangioendothelioma: a new low-grade variant of malignant littoral cell tumour

AIMS

Littoral cell angioma is a recently described splenic vascular tumour of splenic sinus lining cells. Almost all cases of splenic littoral cell tumours hitherto described were benign.

METHODS AND RESULTS

A splenic littoral cell tumour recurred 8 years after splenectomy, with an abdominal mass and multiple liver metastases, resulting in the patient's death. Histologically, the original splenic tumour showed solid areas with small necrotic foci in addition to large areas of typical littoral cell angioma. The recurrent tumours showed increased solid architecture and slightly increased nuclear atypia. The tumours showed an immunohistochemical profile positive for factor VIII, CD31, CD68, cathepsin D, and CD21 and negative for CD34 and CD8, consistent with the immunophenotype of classic littoral cell angioma. Ki67 index in the recurrent tumours was higher than in the primary tumour.

CONCLUSIONS

The mildly atypical, but not frankly malignant, histological features as well as the protracted clinical course support definition of the tumour as 'littoral cell haemangioendothelioma'. Low rate of Ki67 staining and diploid DNA histogram with low S-phase fraction of the tumours are in accordance with a low-grade malignancy. Literature review revealed two other cases of littoral cell tumours with disseminated disease that may be other examples of littoral cell haemangioendothelioma. Littoral cell haemangioendothelioma should be distinguished from the overtly malignant splenic angiosarcomas, of which a few may show splenic lining cell differentiation with some immunohistochemical features of littoral cells. Due to difficulties in predicting biological behaviour based on histological features of splenic littoral cell tumours, a long-term follow-up for these patients, especially for those with atypical histology, is recommended.

High-dose-rate endobronchial brachytherapy in endobronchial metastatic malignant chondroid syringoma

A 65-year-old man with malignant chondroid syringoma (MCS) was found to have pulmonary metastases in the form of multiple pulmonary nodules 4 years after wide excision and adjuvant radiotherapy of a primary abdominal wall tumor. Atelectasis of the lingula due to obstructive endobronchial metastasis, resistant to combination chemotherapy, led us to perform high-dose rate (HDR) endobronchial brachytherapy for the first time in this rare tumor with a favorable response. This case emphasizes the role of HDR brachytherapy as a palliative procedure in endobronchial tumors not responding to other treatment modalities, even those considered to be radioresistant.

Calcifying fibrous pseudotumor of mesentery presenting with acute peritonitis: case report with immunohistochemical study and review of literature

Calcifying fibrous pseudotumor (CFP) is a benign soft tissue lesion composed of thick collagen bundles, scattered fibroblasts, and psammomatous and dystrophic calcifications, located most commonly in the extremities and trunk of children and young adults. The present case in a 36-year-old woman is to the best of our knowledge the first report of a large CFP confined to the mesentery, which, because of torsion, led to acute peritonitis and emergency laparotomy. The typical histologic features were accompanied by a prominent myofibroblastic proliferation along with inflammatory response at the periphery of the lesion. The spindle cells of the lesion were positive for vimentin and focally for CD34 and smooth-muscle actin. Review of the literature and discussion of differential diagnosis in this report focuses on abdominal CFP and other intraabdominal soft tissue lesions, some of which may be precursors of CFP. Int J Surg Pathol 9(3):249-253, 2001

Inverse relation between levels of p27(Kip1) and of its ubiquitin ligase subunit Skp2 in colorectal carcinomas

BACKGROUND

Previous studies have shown that low levels of p27(Kip1), an inhibitor of G1 cyclin-dependent kinases, are associated with high aggressiveness and poor prognosis in a variety of cancers. Decreased levels of p27 are caused, at least in part, by acceleration of the rate of its ubiquitin-mediated degradation. In cultured cells and cell-free biochemical systems, it has been shown that p27 is targeted for degradation by a ubiquitin ligase complex that contains Skp2 (S-phase kinase-associated protein 2) as the specific substrate-recognizing and rate-limiting subunit. This investigation was undertaken to examine the possible relation between levels of p27 and of its specific ubiquitin ligase subunit Skp2 in human cancers.

METHODS

Quick-frozen colorectal tumor samples from 20 patients were homogenized at 0 degrees C in buffer containing a mixture of protease inhibitors. Samples were separated by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, transferred to nitrocellulose, and probed with highly specific monoclonal antibodies directed against Skp2 and p27. The expression of Skp2 also was examined by immunohistochemistry using formalin fixed, paraffin embedded tissue sections from the same cases.

RESULTS

A strongly significant inverse correlation was found between levels of Skp2 and p27 (r = -0.812; P < 0.0001). Thus, decreased levels of p27 were associated with strongly increased levels of Skp2, whereas high levels of p27 coincided with low levels of Skp2. Immunohistochemical examination of Skp2 expression agreed with immunoblot analysis in 89% of cases.

CONCLUSIONS

The results are compatible with the notion that increased expression of Skp2 may have a causative role in decreasing the levels of p27 in aggressive colorectal carcinomas.

Inverse relation between levels of p27(Kip1) and of its ubiquitin ligase subunit Skp2 in colorectal carcinomas

BACKGROUND

Previous studies have shown that low levels of p27(Kip1), an inhibitor of G1 cyclin-dependent kinases, are associated with high aggressiveness and poor prognosis in a variety of cancers. Decreased levels of p27 are caused, at least in part, by acceleration of the rate of its ubiquitin-mediated degradation. In cultured cells and cell-free biochemical systems, it has been shown that p27 is targeted for degradation by a ubiquitin ligase complex that contains Skp2 (S-phase kinase-associated protein 2) as the specific substrate-recognizing and rate-limiting subunit. This investigation was undertaken to examine the possible relation between levels of p27 and of its specific ubiquitin ligase subunit Skp2 in human cancers.

METHODS

Quick-frozen colorectal tumor samples from 20 patients were homogenized at 0 degrees C in buffer containing a mixture of protease inhibitors. Samples were separated by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, transferred to nitrocellulose, and probed with highly specific monoclonal antibodies directed against Skp2 and p27. The expression of Skp2 also was examined by immunohistochemistry using formalin fixed, paraffin embedded tissue sections from the same cases.

RESULTS

A strongly significant inverse correlation was found between levels of Skp2 and p27 (r = -0.812; P < 0.0001). Thus, decreased levels of p27 were associated with strongly increased levels of Skp2, whereas high levels of p27 coincided with low levels of Skp2. Immunohistochemical examination of Skp2 expression agreed with immunoblot analysis in 89% of cases.

CONCLUSIONS

The results are compatible with the notion that increased expression of Skp2 may have a causative role in decreasing the levels of p27 in aggressive colorectal carcinomas.

Renovascular hypertension associated with neurofibromatosis: two cases and review of the literature

The authors report two cases of renovascular hypertension associated with neurofibromatosis. A 19-year-old woman was admitted to our hospital with a complaint of abdominal pain and blood pressure of 180/120 mmHg. Examination revealed café-au-lait spots over her chest and extremities. Peripheral plasma renin activity (PRA) under basal conditions was 2.8 ng/ml/h and increased to 12.6 ng/ml/h after administration of 50 mg captopril. Plasma and urinary catecholamines were normal. Selective renal angiography showed left aneurysmal dilatation of the segmentary branch and right renal artery stenosis with multiple aneurysmal affecting different branches. Blood pressure was controlled by multiple drugs, including beta-blockers and angiotensin-converting enzyme inhibitor. Another patient, a 20-year-old woman, was admitted because of severe arterial hypertension, numerous café-au-lait spots, scoliosis, and mass over the right arm. PRA from the right renal vein was extremely elevated, and selective angiography demonstrated bilateral renal artery stenosis. Aortorenal bypass was performed successfully.

Laryngotracheobronchial involvement in a patient with nonendemic rhinoscleroma

We report the first case of rhinoscleroma in an Israeli citizen, a former sailor with a transatlantic shipping company. Characteristic histologic changes from a tracheal biopsy and isolation of Klebsiella rhinoscleromatis from a blood culture after diagnostic bronchoscopy confirmed the diagnosis. Extreme delay in the diagnosis, a not uncommon feature in nonendemic areas, was associated with severe advanced laryngotracheobronchial disease. Treatment with quinolones was followed by significant improvement, but the patient died 1 month after presentation, apparently from upper airway obstruction.

Cryohemostasis of uncontrolled hemorrhage from liver injury

Uncontrolled hemorrhage is the primary cause of death in both blunt and penetrating liver trauma. Cryohemostasis was attempted in the past for elective liver surgery but did not gain popularity. During past decades, cryoequipment was refined and successfully used for tumor ablation. The purpose of the present study was to assess the efficacy of cryosurgery as a potential adjuvant hemostatic technique in the treatment of grades III-IV liver injuries. A standard liver crush-evulsion injury was created in pigs. In the control group, the liver was left to bleed freely. In the experimental group, the severed liver surface was immediately frozen to -160 degrees C for 10 min, spontaneously thawed, and left to bleed thereafter. Blood pressure, pulse rate, urine output, and serum lactate were monitored. The total blood loss was measured 180 min after liver injury was inflicted. The volume of frozen liver parenchyma was measured. For further laboratory evaluation, three additional experimental animals were not sacrificed and recovered. Cryohemostasis significantly reduced blood loss and substantially attenuated hemorrhagic shock. The frozen liver parenchyma underwent necrosis but did not jeopardize survival. Cryosurgery may be an efficient adjuvant technique in the early control of hemorrhage in grades III-IV liver injury.

Primary malignant melanoma of the anterior mediastinum in a child

Primary malignant melanoma of the mediastinum is extremely rare. We report a case not previously reported of primary malignant melanoma located in the mediastinum in a 11-year-old boy. The tumor could not be completely resected as a result of extensive invasion of the large blood vessels. Histologically, the tumor was heavily pigmented and composed of vague fascicles of spindle cells intermingled with epithelioid cells. Immunohistochemical analysis showed vimentin, S-100 protein, Melan-A, and HMB-45 immunoreactivity in most of the tumor cells. Nearly 50% of the tumor cells were also positive for p53. It is suggested that primary malignant melanoma of the anterior mediastinum may have a histogenetic relationship to the recently described aggregates of nevus cells in the thymus or mediastinal lymph nodes.

Pleomorphic hyalinizing angiectatic tumor of soft parts: immunohistochemical study including the expression of vascular endothelial growth factor

We report morphologic, flow cytometric, and immunohistochemical findings in two cases of pleomorphic hyalinizing angiectatic tumor of soft parts. Both patients were middle-aged women with subcutaneous lesions located in the lower extremity. The tumors consisted of sheets of spindled and pleomorphic cells with frequent intranuclear pseudoinclusions associated with clusters of ectatic vessels surrounded by prominent perivascular hyaline material. Numerous, nonhyalinized vessels were also present, mostly in the peripheral areas of the lesions. Some of these vessels had their walls permeated by numerous small capillaries. Immunostaining for vascular endothelial growth factor (VEGF), a secreted protein that has been implicated in tumor-associated angiogenesis, demonstrated positive staining in both tumoral and endothelial cells. Tumor cells were also reactive to vimentin and CD34. Focal positivity for CD99 and factor XIIIa was also present. Flow cytometry yielded a diploid DNA histogram with S-phase fraction of 7%. Our findings corroborate those from previously reported cases. They further suggest that angiogenesis and the angiogenic factor VEGF may play a role in the development of this peculiar tumor.