The Peritoneal Macrophages in Inflammatory Diseases and Abdominal Cancers.

Peritoneal macrophages (PMs) are the major cell type of peritoneal cells that participate in multiple aspects of innate and acquired immunity in the peritoneal cavity. PMs have an ability to release a large amount of proinflammatory and anti-inflammatory cytokines and therefore play a critical role in regulating the differentiation of innate immune cells and inflammatory T cells. Accumulating studies demonstrate that the immunological reactions and inflammatory responses of PMs are strongly related to the pathogenic processes of various inflammatory diseases and abdominal cancers. Consequently, the regulation of PM activation has gradually emerged as a promising target for immunotherapy, and better understanding of the distinctly biological function of PMs in individual diseases is crucial for designing specific and effective therapeutic agents. This review covers the characterization and immunological function of PMs in hosts with inflammatory diseases and abdominal cancers.

Dehydroepiandrosterone modulates T-cell response after major abdominal surgery.

BACKGROUND: The immune balance controlled by T-helper (Th)1 and Th2 cells is critical in protecting the host from pathogenic invasion, and its imbalance may increase susceptibility to infection in patients undergoing major surgery. The differentiation of naive T cells to Th1 and Th2 cells is largely driven by cytokines. In addition, steroid hormones have been shown to affect Th1/Th2 balance, particularly in autoimmune diseases. The regulation of Th1/Th2 balance in patients undergoing surgery and its potential clinical relevance remain unclear. MATERIALS AND METHODS: Blood samples were obtained from patients both before and 2 h after major abdominal surgery. Peripheral blood mononuclear cells were isolated and cultured in wells coated with either anti-CD3 (direct T-cell stimulation) or phytohemagglutinin (PHA) (indirect T-cell stimulation), with or without 10(-5) M dehydroepiandrosterone (DHEA). The release of interleukin (IL)-2, interferon gamma, and IL-10 was measured by an enzyme-linked immunosorbent assay, and the expression of CD4, CD8, and CD69 was determined by flow cytometry. RESULTS: DHEA decreased the release of IL-2 and IL-10 in directly (anti-CD3) and indirectly (PHA)-stimulated T cells from postoperative samples, whereas the release of interferon gamma in PHA-stimulated T cells was not affected. The distribution of CD4/CD8 was not significantly different after surgery or DHEA. DHEA was associated with a decrease in the expression of the activation marker CD69 on CD4(+) T cells, whereas the activation of CD8(+) T cells remained unchanged. CONCLUSIONS: These results demonstrate that DHEA plays a critical role in controlling Th1/Th2 balance in the immediate postoperative period. Attenuation of both the Th1 and Th2 responses has been suggested to have immunoprotective effects. The role of DHEA in the regulation of Th1/Th2 balance in patients undergoing major abdominal surgery may, therefore, also be of significant clinical relevance and warrants further investigation.

Spontaneous regression of metastatic melanoma - clinical evidence of the abscopal effect.

INTRODUCTION: Metastatic melanoma is poorly understood. Regression of primary lesions has been associated with poor prognosis, but spontaneous regression of all metastatic disease is clearly beneficial. A patient's own immune responses occasionally appear to stimulate spontaneous regression of metastatic disease in melanoma. PATIENTS AND METHODS: We present six interesting cases of complete or nearly complete spontaneous regression of metastatic melanoma, suggest possible causes and review the literature. RESULTS AND CONCLUSIONS: These cases show clear radiological, pathological or clinical evidence of spontaneous regression of metastatic melanoma. This remains a poorly understood phenomena warranting further investigation and may prove useful in the development of immune mediated solutions.

[Local injection of BRM-activated killer cells into an abdominal wall tumor].

Based on the concept of living with cancer, wherein the goal is to help patients with highly advanced solid cancers maintain a high quality of life(QOL)without adverse events and drug resistance, we developed a new immunocyte therapy based on BRM-activated killer(BAK)cells, which are primarily CD56 positive lymphocytes. In a previous report, we documented the disappearance of liver metastases, as assessed by positron emission tomography-computed tomography(PET-CT), in patients with metastatic liver cancers into which BAK immunocytes had been administered via injection into the hepatic artery. Herein, upon the patient's request, we locally injected BAK lymphocytes into an abdominal tumor. In BAK therapy, 20 mL of peripheral blood are collected from a patient. Lymphocytes from this blood sample are subsequently activated and multiplied with immobilized anti-CD3 antibodies and IL-2 and are cultured for 2 weeks with E(bina)and serum-free ALys media to yield approximately 10 billion autologous lymphocytes. On the final day of incubation, the lymphocytes are treated with 1,000 units/mL of interferon(IFN)-a for 15 minutes to enhance their therapeutic killing effects. During the second week, approximately 10 billion isolated autologous lymphocytes are suspended in 200 mL of Ringer's solution and are then drip-infused into the patient over a period of 1 hour. We injected approximately 10 billion BAK lymphocytes suspended in 50 mL of Ringer's solution into a 2-cm abdominal tumor in a single 60-year-old woman under ultrasonography guidance. This procedure was repeated every 3 weeks. After the third administration, we collected a biopsy specimen and examined it using PAS staining and microscopy. The 3 separate local injections of approximately 10 billion activated autologous lymphocytes each, primarily CD56 positive cells, into the tumor led to tumor fragmentation, leaving approximately 10 lymphocytes surrounding each cancer cell. These results suggest that BAK therapy is efficacious and show that locally administered BAK lymphocytes can reach cancer tissues and effectively kill cancer cells.

Minimally invasive surgery in cancer. Immunological response.

Minimally invasive surgery produced major changes in treating abdominal malignancies and early stage lung cancer. Laparoscopy and thoracoscopy are less traumatic than open surgery: allow faster recovery, shorter hospital stay, better cosmesis. Although these clinical benefits are important, prolonged disease-free interval, long-term survival with improved quality of life are most important endpoints for oncologic surgery. Major surgery causes significant alteration of immunological response, of particular importance in oncologic patients, as postoperative immunosuppression has been related to septic complications, lower survival rate, tumor spread and metastases. Clinical studies have shown laparoscopic surgery preserves better the patient's immunological function. Postoperative plasma peak concentrations of IL-6, IL-10, C-reactive protein (CRP) and TNF-alpha were lower after laparoscopic colonic resection. Prospective thoracoscopic VATS lobectomy trials found better preservation of lymphocyte T-cell function and quicker return of proliferative responses to normal, lower levels of CRP, thromboxane and prostacyclin. Immune function is influenced by the extent of surgical trauma. Minimally invasive surgery show reduced acute-phase responses compared with open procedures and better preservation of cellular immune mechanisms.

Excessive blinking and ataxia in a child with occult neuroblastoma and voltage-gated potassium channel antibodies.

A previously healthy 9-year-old girl presented with a 10-day history of slowly progressive unsteadiness, slurred speech, and behavior change. On examination there was cerebellar ataxia and dysarthria, excessive blinking, subtle perioral myoclonus, and labile mood. The finding of oligoclonal bands in the cerebrospinal fluid prompted paraneoplastic serological evaluation and search for an occult neural crest tumor. Antineuronal nuclear autoantibody type 1 (anti-Hu) and voltage-gated potassium channel complex antibodies were detected in serum. Metaiodobenzylguanidine scan and computed tomography scan of the abdomen showed a localized abdominal mass in the region of the porta hepatis. A diagnosis of occult neuroblastoma was made. Resection of the stage 1 neuroblastoma and treatment with pulsed corticosteroids resulted in resolution of all symptoms and signs. Excessive blinking has rarely been described with neuroblastoma, and, when it is not an isolated finding, it may be a useful clue to this paraneoplastic syndrome. Although voltage-gated potassium channel complex autoimmunity has not been described previously in the setting of neuroblastoma, it is associated with a spectrum of paraneoplastic neurologic manifestations in adults, including peripheral nerve hyperexcitability disorders.

Inflammatory myofibroblastic tumor presenting as an abdominal wall mass in an adult patient.

Inflammatory myofibroblastic tumor of the abdominal wall is a rare soft-tissue tumor presentation in adults. A 50-year-old woman was referred with abdominal pain and a palpable mass in the left lower quadrant. Computed tomography scan and magnetic resonance investigation revealed an 8-cm heterogeneous abdominal wall mass. Tumor markers were within normal limits. Fine-needle aspiration cytology and tru-cut biopsies yielded necrotic material. A preoperative diagnosis of a resectable rhabdomyosarcoma was suggested. On exploration a tumor measuring 8 x 8 x 6 cm was resected along with the involved structures. Histopathologic examination of specimen revealed an inflammatory myofibroblastic tumor of the abdominal wall. The patient has been followed up for the last 12 months without clinical or radiographic evidence of recurrence. Inflammatory myofibroblastic tumor arising from the anterior abdominal wall in adults is an unusual manifestation of soft-tissue tumors, which can be managed by a multidisciplinary team of surgeons, oncologists, radiologists and pathologists.

Distinct populations of metastases-enabling myeloid cells expand in the liver of mice harboring invasive and preinvasive intra-abdominal tumor.

The liver is the most common site of adenocarcinoma metastases, even in patients who initially present with early disease. We postulated that immune-suppressive cells in the liver of tumor-bearing hosts inhibit anti-tumor T cells, thereby accelerating the growth of liver metastases. Using models of early preinvasive pancreatic neoplasia and advanced colorectal cancer, aims of this study were to determine immune phenotype, stimulus for recruitment, inhibitory effects, and tumor-enabling function of immune-suppressive cells in the liver of tumor-bearing hosts. We found that in mice with intra-abdominal malignancies, two distinct CD11b(+)Gr1(+) populations with divergent phenotypic and functional properties accumulate in the liver, becoming the dominant hepatic leukocytes. Their expansion is contingent on tumor expression of KC. These cells are distinct from CD11b(+)Gr1(+) populations in other tissues of tumor-bearing hosts in terms of cellular phenotype and cytokine and chemokine profile. Liver CD11b(+)Gr1(+) cells are highly suppressive of T cell activation, proliferation, and cytotoxicity and induce the development of Tregs. Moreover, liver myeloid-derived suppressor cells accelerate the development of hepatic metastases by inactivation of cytotoxic T cells. These findings may explain the propensity of patients with intra-abdominal cancers to develop liver metastases and suggest a promising target for experimental therapeutics.

Sclerosing angiomatoid nodular transformation of the spleen (SANT): clinicopathological study of 10 cases with or without abdominal disseminated calcifying fibrous tumors, and the presence of a significant number of IgG4+ plasma cells.

Sclerosing angiomatoid nodular transformation (SANT) is a peculiar splenic vascular lesion that is characterized by marked stromal sclerosis and the presence of plasma cells, which shares histopathological features associated with IgG4-related sclerosing disease. The cinicopathological features of 10 cases of SANT were reviewed and immunohistochemistry with IgG4 and IgG antibodies was performed. Nine other various splenic lesions served as controls. Five cases of SANT were found incidentally. Three cases of SANT had multiple tumors and five had associated abdominal disseminated calcifying fibrous tumors (CFT). IgG4+ plasma cells were found in all of the cases of SANT and in calcifying fibrous tumors. The densities of IgG4+ and IgG+ cells and the IgG4/IgG ratios were significantly higher in SANT than in control spleens (P= 0.001, 0.006, and 0.028, respectively). Serum IgG4 concentration was elevated in one case. In conclusion, SANT can occur either as a solitary or as multiple tumors. Frequent association with abdominal disseminated CFT simulating carcinomatosis was observed. A statistically significant number of IgG4+ plasma cells was found in all of the cases of SANT and the associated CFT. Whether they are related to the IgG4-related sclerosing disease or not is debatable and warrants further investigation.

Hepatoid carcinoma of the skin: spontaneous rat skin hepatoid carcinoma with eosinophilic globules and crystals immunoreactive to alpha-1-antitrypsin.

We present a case of hepatoid carcinoma of the abdominal skin in a male Wistar rat. Histopathologically, this carcinoma resembled human hepatocellular carcinoma with respect to trabecular-sinusoidal structures. Carcinoma tissues contain numerous eosinophilic globules and crystals, and in this case, we found the characteristic eosinophilic globules in the hepatoid carcinoma cells and the crystals in the extracellular portions. Vivid carcinoma cells full of eosinophilic globules were present near the necrotic areas in tumor tissue, wherein quadrate crystals unstained with eosin were observed. PAS staining after diastase digestion revealed that the globules were PAS positive and diastase resistant. In addition, we found that the hepatoid carcinoma cells were immunoreactive for alpha-1-antitrypsin (anti-A1AT) antibody with the globules and crystals staining peripherally, and a central unstained region. Ultrastructural study of intracytoplasmic globules and extracellular crystals revealed that the fringe of each globule and crystal had no limiting membrane and showed the same level of electron density. These findings suggest that the characteristic crystals in this tumor may have originated from the globules that were emitted from the carcinoma cells after their death as a result of saturation with intracytoplasmic globules.

Effector T cell analysis of melanoma tumor-infiltrating lymphocyte cultures using HLA-ABC semimatched melanoma cell lines.

The generation of T cells with specific reactivity against tumor-associated antigens is prerequisite for adoptive transfer therapy. Melanoma-specific lymphocyte cultures can be established from tumor-infiltrating lymphocytes (TILs) by in vitro culture with high levels of interleukin-2. In this report, we present TIL data originating from 728 attempted cultures from 33 consecutive melanoma biopsy specimens originating from 30 patients. Cultures were analyzed for the presence of interferon gamma (IFNgamma)-producing cells upon stimulation with a panel of HLA-ABC semimatched melanoma cell lines. We sought to find whether such cell lines could be used to analyze TIL reactivity. Cell lines were used as stimulators to circumvent the need for autologous primary tumor cells. Melanoma-reactive cultures were identified by flow cytometry in 25 of the 30 patients. Four hundred forty-four of 728 (60.9%) cultures contained TILs at the end of experiment. Ninety-one of 318 cultures (28.6%) contained IFNgamma-producing cells after stimulation. In HLA-A*0201 patients IFNgamma analysis was complemented with melanoma-specific tetramer staining. All but one HLA-A*0201 patient had MART-1/Melan-A27-35-directed TILs, with frequencies ranging from 0.1% to 90% of CD8 cells. In addition, tetramer analysis also identified TILs directed against gp100, Tyrosinase, and Her2Neu. Tumor material was collected via needle biopsy in 16 cases and surgery in 18 cases. Overall, surgical material generated more cultures positive for T cells. The described methods are efficient in characterizing clinically relevant melanoma-reactive TILs.

Inflammatory myofibroblastic tumor of mesentery: a case report.

INTRODUCTION: Inflammatory myofibroblastic tumor occurring at intra-abdominal sites in children has rarely been described. In the abdomen, mesentery is a rare location for an inflammatory myofibroblastic tumor. CASE REPORT: A case report of inflammatory myofibroblastic tumor of mesentery presenting as painless abdominal swelling is presented. Histopathological study of specimen documented the diagnosis. Complete resection of tumor was done with no recurrence seen in follow-up.

Cross-priming of T cells to intracranial tumor antigens elicits an immune response that fails in the effector phase but can be augmented with local immunotherapy.

Central nervous system (CNS) tumors are thought to be poorly immunogenic. However, whether defective anti-tumor immunity is a consequence of a relative failure of T cell priming versus a deficient effector phase of the anti-tumor immune response is not clear. We utilized a well-defined model system of B16 melanoma expressing the model antigen SIY-GFP to evaluate tumor antigen cross-priming and tumor rejection from the CNS versus subcutaneous compartments. We observed that B16-SIY cells implanted in the CNS were capable of inducing T cell priming as measured by IFN-gamma ELISPOT in the spleen. Cross-priming occurred in the absence of detectable systemic dissemination of the tumor. Despite the induction of a T cell response, CNS tumors grew progressively and were fatal, whereas the same tumor implanted in the flank was rejected. To study the effector phase of the immune response in more detail, in vitro primed 2C/RAG2-/- TCR transgenic CD8+ cells, which recognize the SIY peptide, were adoptively transferred. In addition, the CNS microenvironment was modulated by intracranial delivery of IL-2. While mice that received primed 2C cells alone showed an increase in survival, co-administration of intracranial IL-2 led to a marked prolongation of survival, with 20% of mice surviving at least 120 days. Our results demonstrate that CD8+ T cell cross-priming does indeed occur in response to a CNS tumor, but that manipulation of the brain tumor microenvironment may be necessary to support the effector phase of the anti-tumor immune response.

Antitumor effects of recombinant human prolactin in human adenocarcinoma-bearing SCID mice with human NK cell xenograft.

To survey the immune regulatory function of recombinant human prolactin (rhPRL) and its potential application in adoptive immunotherapy, CB17-SCID mice were loaded with human colon adenocarcinoma HT-29 cells (5 x 10(5) cells/mouse, i.p.) 24 h before adoptive transfer with the purified human NK cells followed by rhPRL injection (10 mug/mouse, every other day for a total of 10 injections). Upon analysis, rhPRL did not exert any direct inhibitory effects on HT-29 cells but slightly improved the tumor cell growth both in vitro and in vivo. After SCID mice were reconstituted with human NK cells, rhPRL improved the antitumor effects of human NK cells in HT-29-bearing SCID mice, showing a prolonged survival from 70.4 to 112.1 days, and the increased survival rate from all died to 40% survival for more than 160 days. rhPRL improved the proliferation of human NK cells with or without PHA stimulation. rhPRL also directly enhanced the cytotoxicity of human NK cells against HT-29 tumor cells in 4-h coculture. The supernatant of rhPRL-stimulating NK cells inhibited the proliferation of HT-29 cells through, at least partly, the interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in the supernatant. Thus, rhPRL administration in HT-29 tumor-bearing SCID mice promotes the antitumor effects of adoptively transferred NK cells.

Immunological advantages of advanced laparoscopy.

Surgical trauma causes significant alterations in host immune function. Compared with open surgery, laparoscopic surgery is associated with reduced postoperative pain and more rapid return to normal activity. Experimental data have also shown more aggressive tumor establishment and growth rates following open surgery and laparoscopic surgery. Surgery-related immunosuppression may be partly responsible for the differences in cancer growth and outcome noted. It is clear that the choice of abdominal surgical approach has immunologic consequences. Further studies are needed to better the time course and extent of surgery-related alterations in the immune system and their clinical importance. A better understanding of the impact of surgery on the immune system may provide opportunities for pharmacologic manipulation of postoperative immune function to improve clinical results.

Huge IgD plasmacytoma in the abdomen presenting coagulation necrosis.

A 65-year-old Japanese woman was diagnosed in 1996 with a pathological fracture of the left femur caused by immunoglobulin D-type myeloma (IgD myeloma). She responded well to combination chemotherapy followed by irradiation. The patient experienced renal failure and became dependent on haemodialysis. In 1999, large plasmacytomas developed in the abdomen and left humerus. The abdominal tumour appeared to induce gastroduodenal ulcers and jejunal obstruction. We initiated irradiation therapy without chemotherapy to prevent further growth of the plasmacytoma, although treatment-resistant gastroduodenal ulcers developed. Continued blood loss from the gastroduodenal ulcers resulted in a deterioration in the patient's health, which prevented successful haemodialysis. An autopsy showed that the plasmacytoma had undergone coagulation necrosis. We conclude that the use of combination chemotherapy with topical irradiation was an acceptable treatment measure against IgD plasmacytoma; irradiation without chemotherapy was the most likely cause of the coagulation necrosis seen in the plasmacytoma at autopsy.

[A case report of extrahepatic hepatocellular carcinoma with lymphocytic infiltration]. / Carcinome hépatocellulaire à stroma lymphoïde extrahépatique. A propos d'un cas.

Hepatocellular carcinoma (HCC) with lymphocytic infiltration is a rare entity recently described, sometimes associated with hepatitis C. Histologically, remarkable inflammatory cell infiltration of cancer nests is observed, mostly composed of T cytotoxic lymphocytes. When prominent, this inflammatory cell component can obscure the neoplastic cells, leading to diagnostic difficulty. Alike tumors showing dense lymphocytic infiltrate, it discloses a better prognosis than other HCC. We report a case of HCC with lymphocytic infiltration arising in the right suprarenal space, in a 45-year-old man with no chronic liver disease. The patient is alive without recurrence three years after surgical resection. This report is original because HCC growing ectopically are rare and need to be distinguished, specially in the right retroperitoneal, from metastatic adrenal HCC.

[Study of the therapeutic effects of costimulatory molecules B7-1 and interleukin 12 modified tumor cells vaccines on ovarian epithelial carcinoma through induction of anti-cancer immunity of the body].

OBJECTIVE: To study the biological characters of tumor cell vaccines modified by interleukin 12 (IL-12) and co-stimulatory molecule B(7 - 1) and their combination therapeutic effect on rat ovarian cancer animal model. METHODS: Retroviral vector pLmB(7 - 1)SN, which expressed murine B(7 - 1) was constructed. An epithelial ovarian cancer cell line NuTu-19 was infected with pLmIL-12SN and/or pLmB(7 - 1)SN by lipofectin-mediated gene transfer system. Cell lines that could highly express either or both of these cytokines were named NuTu-19/IL-12, NuTu-19/B(7 - 1) or NuTu-19/IL-12-B(7 - 1), according to the results of enzyme-linked immunosorbent assay (ELISA) and flow cytometry (FCM). NuTu-19/Neo, the cell line that was transfected by vector pLXSN was used as a control. Various types of cytokine-modified tumor cells were injected subcutaneously into syngeneic rats Fischer 344 and their tumorigenecities were recorded. After being immunized twice by various types of mitomycin C treated gene modified tumor cells, the survival time of the intraperitoneal disseminating ovarian cancer animal model was observed, and the anti-tumor mechanisms of different gene modified tumor cell lines were discussed. RESULTS: The reconstruction of pLmB(7 - 1)SN was successful. Stable IL-12 and B(7 - 1) expression in cell lines NuTu-19/B(7 - 1), NuTu-19/IL-12 and NuTu-19/IL-12-B(7 - 1) were confirmed by ELISA and FCM. Tumorigenecities of various gene modified tumor cells decreased in syngeneic rats. The splenic lymphocytes proliferation indices (PI) in B(7 - 1) group (NuTu-19/B(7 - 1) immunized group) and IL-12 group (NuTu-19/IL-12 immunized group) were 2.4 and 4.6 (the letter P < 0.05 compared with that in control group), while PI in B(7 - 1) and IL-12 combination group (NuTu-19/IL-12-B(7 - 1) immunized group) increase to 10.2, being of significantly difference compared with those in control or B(7 - 1) or IL - 12 group (P < 0.01). More significant cytotoxic effects of cytotoxic lymphocytes (CTLs) on syngeneic tumor cells could be observed in B(7 - 1) group (15.0%) or IL-12 group (31.5%) (P < 0.05 or P < 0.01, compared with 2.6% in control group), while coexpression of IL-12 and B(7 - 1) was of great importance in enhancing CTL activity (52.4%), compared with that in control or B(7 - 1) or IL-12 group (P < 0.05, respectively). The life spans of ovarian cancer-bearing rats immunized by IL-12 (59.8 d) or B(7 - 1) (56.2 d) tumor cell vaccines were a little longer than that in control group (53.4 d), but no significant differences existed (P > 0.05), whereas in the animal models who had received IL-12 and B(7 - 1) co-immunization, prolonged survival time was showed which had statistical significance compared with that in control group (66.0 d, P < 0.05). CONCLUSION: B(7 - 1) and IL-12 modified tumor cell vaccines can induce anti-tumor immunity through stimulating lymphocytes proliferation and inducing recognition and cytotoxic effects of CTLs on tumor cells. An obvious synergistic effect exists when the two cytokines are combined. Combined immunogenic therapy with IL-12 and B(7 - 1) should prove to be a promising therapeutic strategy in ovarian cancer.

Desmoplastic small round cell tumor: a clinicopathologic, immunohistochemical, and molecular study of 32 tumors.

Desmoplastic small round cell tumor is a rare, aggressive neoplasm that mainly affects young male patients and is characterized by a reciprocal translocation t(11;22)(p13;q12) associated with the EWS-WT1 gene fusion transcript. Clinical, histopathologic, immunohistochemical, and molecular genetics features were reviewed for 32 tumors. There were 29 male and three female patients, with ages from 6 to 54 years (mean, 25 years). The main clinical signs and symptoms included abdominal pain (eight patients), weight loss (five patients), and presence of umbilical hernia (four patients). Two tumors primarily involved the ethmoid sinus and the soft tissues of the scalp; the other tumors (mean size, 10 cm) involved the abdominal cavity (88%). One patient presented initially with an axillary lymph node metastasis. Generally, all tumors showed the typical histologic findings of variably sized clusters of small, round, or spindled cells lying in a desmoplastic stroma. The neoplastic cells in formalin-fixed, paraffin-embedded tissue sections were positive for desmin (dot pattern) (81% of the cases), WT1 (91%), keratin (87%), neuron-specific enolase (84%), CD99 (23%), and actin (3%). The EWS-WT1 gene fusion transcript was detected in 29 of 30 tumors. One tumor with typical clinicopathologic and immunohistochemical features did not show the gene fusion. Follow-up for 27 patients showed that 19 patients (70%) died of uncontrolled, local, or widespread metastatic disease 3-46 months (mean, 20 months) after diagnosis, and eight patients were alive with known evidence of disease. Occasionally, desmoplastic small round cell tumor lacks the classic clinical, histologic, and immunohistochemical features. This study emphasizes the utility of analysis of the EWS-WT1 gene fusion transcript, which was performed on paraffin-embedded tissues, to confirm the diagnosis.