Desmoplastic small round cell tumor: report of a case presenting as a primary ovarian neoplasm.

BACKGROUND: Desmoplastic small round cell tumor (DSRCT) is an intra-abdominal malignancy that typically has extensive peritoneal spread at the time of diagnosis. We report a case of DSRCT with involvement of the ovary and omentum as well as an elevated CA-125 level at presentation. CASE: A 23-year-old female presented to another institution with a pelvic mass and a CA-125 level of 140 U/ml. During tumor reductive surgery the right ovary, omentum, and liver were found to be involved. Initial histologic examination favored an undifferentiated small cell carcinoma of the ovary. The patient received two cycles of Taxol and cisplatin chemotherapy and was referred to the University of Texas M. D. Anderson Cancer Center. Upon review of the pathology material at the time of the referral, a diagnosis of DSRCT was made. Despite two additional cycles of chemotherapy, the tumor progressed, and the patient returned home. CONCLUSION: DSRCT may mimic an ovarian primary tumor by presenting with involvement of the ovary and an elevated CA-125 level, and should be included in the differential diagnosis of ovarian neoplasms in young patients.

Identification of carbohydrate-binding domains in the attachment proteins of type 1 and type 3 reoviruses.

The reovirus attachment protein, sigma1, is responsible for strain-specific patterns of viral tropism in the murine central nervous system and receptor binding on cultured cells. The sigma1 protein consists of a fibrous tail domain proximal to the virion surface and a virion-distal globular head domain. To better understand mechanisms of reovirus attachment to cells, we conducted studies to identify the region of sigma1 that binds cell surface carbohydrate. Chimeric and truncated sigma1 proteins derived from prototype reovirus strains type 1 Lang (T1L) and type 3 Dearing (T3D) were expressed in insect cells by using a baculovirus vector. Assessment of expressed protein susceptibility to proteolytic cleavage, binding to anti-sigma1 antibodies, and oligomerization indicates that the chimeric and truncated sigma1 proteins are properly folded. To assess carbohydrate binding, recombinant sigma1 proteins were tested for the capacity to agglutinate mammalian erythrocytes and to bind sialic acid presented on glycophorin, the cell surface molecule bound by type 3 reovirus on human erythrocytes. Using a panel of two wild-type and ten chimeric and truncated sigma1 proteins, the sialic acid-binding domain of type 3 sigma1 was mapped to a region of sequence proposed to form the more amino terminal of two predicted beta-sheet structures in the tail. This unit corresponds to morphologic region T(iii) observed in computer-processed electron micrographs of sigma1 protein purified from virions. In contrast, the homologous region of T1L sigma1 sequence was not implicated in carbohydrate binding; rather, sequences in the distal portion of the tail known as the neck were required. Results of these studies demonstrate that a functional receptor-binding domain, which uses sialic acid as its ligand, is contained within morphologic region T(iii) of the type 3 sigma1 tail. Furthermore, our findings indicate that T1L and T3D sigma1 proteins contain different arrangements of receptor-binding domains.