Neurofibromatosis type 1 (NF1) is one of the most common genetic disorders. NF1 is a complex disease resulting from a spectrum of mutations that may occur at many locations along the large, complex NF1 gene, which is located on chromosome 17. Mutations of the NF1 gene lead to abnormal tumor suppression. Consequently, patients with NF1 have an increased prevalence of benign and malignant neoplasms throughout the body. There are five categories of NF1 tumors that occur in the abdomen: neurogenic, neuroendocrine, nonneurogenic gastrointestinal mesenchymal, embryonal, and miscellaneous. Many of these tumors are age related, occur at specific anatomic locations, and have unique imaging features. Notably, many patients have a variety of organs affected because there is a high prevalence of multiple tumors occurring in the same patient. Neurofibromas are the most common benign neoplasms and may occur in the retroperitoneum or visceral organs. Malignant peripheral nerve sheath tumor is an aggressive malignancy that is the most common malignant tumor of the abdomen in patients with NF1. Interpreting abdominal imaging studies in patients with NF1 can be challenging because of the wide spectrum and diverse nature of tumors that occur in this disease.

This report describes 3 cases of a distinctive, hitherto unreported gastric epitheliomesenchymal biphasic tumor that differs from other biphasic tumors of the stomach and elsewhere: carcinosarcoma, biphasic synovial sarcoma, teratoma, and mixed tumor. The tumors occurred in young adults, 2 males and 1 female, of ages 19, 27, and 30 years. Two tumors were located in the greater curvature in the gastric body and one in the antrum. The tumors measured 5, 6, and 15 cm in maximum diameter, and their mitotic rates were 0, 4, and 30 mitoses per 50HPF. There were 2 components: uniform oval or spindled cells in diffuse sheets, and clusters or cords of epithelial cells occasionally forming glandular structures with small lumens. The epithelial elements were positive for keratin cocktail AE1/AE3, keratin 18, and partly for keratin 7, but were negative for keratins 5/6, 20 and epithelial membrane antigen. The spindle cells were positive for vimentin and CD10. All components were negative for CD34, CD99, estrogen receptor, KIT, smooth muscle actin, desmin S100 protein, p63, calretinin, chromogranin, synaptophysin, CDX2, and thyroid transcription factor 1. In situ hybridization for SS18 rearrangement was negative in all cases separating this tumor from synovial sarcoma. All 3 patients were alive after follow-up of 3.5, 5, and 14 years. Because these tumors have some resemblance to blastomas of other organs, we propose the term "gastroblastoma" for this distinctive, at least low-grade malignant epitheliomesenchymal tumor of the stomach.

The purpose of this report is to record a patient with myelodysplastic syndrome (MDS) associated acute myelogenous leukemia (AML) and leukemia cutis who had blast expression of the neural cell adhesion molecule (NCAM) and to review the world literature on prognostic implications of extramedullary myeloid cell tumors (granulocytic sarcoma, myeloblastoma, chloroma and leukemia cutis) in MDS and MDS associated AML. Case report and world literature from January 1965-January 1994 for all cases of MDS-associated extramedullary myeloid cell tumors (EMT) is reviewed, and the first patient with EMT, MDS associated AML and blast expression of NCAM is described. There have been 46 cases of MDS associated EMT previously reported. 32 cases occurred in the absence of AML. AML developed in 47% of these patients at a mean of 38 weeks from initial EMT. Of the patients not developing AML, median survival from initial EMT was 11 weeks. Nine patients received chemotherapy at the time of EMT and had a median survival of 36 weeks. The median survival for patients receiving conservative therapy for EMT was 48 weeks. Patients (n = 15) with EMT and MDS associated AML had a poor outcome regardless of therapy with a median survival of 11 weeks. Unlike other forms of isolated EMT, MDS associated EMT is not always a forerunner of AML. Premature induction therapy for MDS associated EMT does not appear to prolong survival. EMT in the setting of MDS associated AML is associated with a poor prognosis despite aggressive chemotherapy. Blast expression of NCAM may prove to be a risk factor for EMT in MDS associated AML.

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Activation of peripheral blood CD4+ helper T lymphocytes establishes a permissive state for growth of HIV-1. Activated T lymphocytes expressed increased sialidase (neuraminidase) activity and were hyposialylated. Treatment of freshly isolated peripheral blood mononuclear cells (PBMCs) with microbial neuraminidase (NANase) or phytohemagglutinin (PHA) prior to infection at low multiplicity with T cell line-adapted HIV-1IIIB resulted in production of large amounts of p24 antigen and reverse transcriptase. In contrast, neither viral component was detected in the medium of mock-treated cells infected at a similar multiplicity through 21 days in culture. The titer of a stock solution of HIV-1IIIB was 1.4 +/- 0.18 log10 greater in NANase-treated PBMCs than in mock-treated cells; the titer was similarly raised 1.5 to 1.76 +/- 0.18 log10 in PHA-treated cells. Growth of the primary isolate HIV-1(91/US/056) was also enhanced in NANase-treated PBMCs; the titer of a stock solution of HIV-1(91/US/056 was 1.0 +/- 0.16 log10 greater in NANase-treated PBMCs than in mock-treated cells 7 days after infection. No enhancement of viral growth in PBMCs was detected when NANase was heat-inactivated or specifically inhibited with 2,3-dehydro-2-desoxy-N-acetyl-neuraminic acid prior to use. Treatment of PBMCs with NANase did not alter the distribution of lymphocyte subsets nor change the density of CD4 antigen per cell after 7 days in culture. Whereas PHA treatment of PBMCs was mitogenic, pretreatment with NANase was not; the amount of [3H]thymidine incorporated into DNA and culture growth characteristics were similar for NANase- and mock-treated cells. Thus, desialylation of PBMCs promoted a permissive state for growth of HIV-1 without affecting the rate of DNA synthesis or relative number of target CD4+ cells.