Oligodendroglial neoplasms are a subgroup of gliomas with distinctive morphological characteristics. In the present study we have evaluated a series of these tumors to define their molecular profiles and to determine whether there is a relationship between molecular genetic parameters and histological pattern in this tumor type. Loss of heterozygosity (LOH) for 1p and 19q was seen in 17/23 (74%) well-differentiated oligodendrogliomas, in 18/23 (83%) anaplastic oligodendrogliomas, and in 3/8 (38%) oligoastrocytomas grades II and III. LOH for 17p and/or mutations of the TP53 gene occurred in 14 of these 55 tumors. Only one of the 14 cases with 17p LOH/TP53 gene mutation also had LOH for 1p and 19q, and significant astrocytic elements were seen histologically in the majority of these 14 tumors. LOH for 9p and/or deletion of the CDKN2A gene occurred in 15 of these 55 tumors, and 11 of these cases were among the 24 (42%) anaplastic oligodendrogliomas. Comparative genomic hybridization (CGH) identified the majority of cases with 1p and 19q loss and, in addition, showed frequent loss of chromosomes 4, 14, 15, and 18. These findings demonstrate that oligodendroglial neoplasms usually have loss of 1p and 19q whereas astrocytomas of the progressive type frequently contain mutations of the TP53 gene, and that 9p loss and CDKN2A deletions are associated with progression from well-differentiated to anaplastic oligodendrogliomas.

Pilomatrixoma is a cutaneous neoplasm that is one of most common causes of superficial head and neck masses in children. Although the presurgical diagnosis may be difficult in some cases, pilomatrixoma must be kept in the differential of superficial head and neck masses in children. Surgical excision is almost always curative.

Trichodysplasia spinulosa (TS) is a folliculocentric and clinically papular dermatological disorder occurring in the setting of immunosuppression typically in association with solid organ transplantation or hematolymphoid malignancies. We report the occurrence of TS in a 7-year-old girl with Down syndrome and pre-B-acute lymphoblastic leukemia (pre-B-ALL) who was completing chemotherapy at onset. The patient’s affected follicles were dilated by an expansion of a dystrophic follicular inner root sheath cell population displaying enlarged trichohyaline cytoplasmic granules and progressing centrally to keratotic and parakeratotic debris, and superficially demonstrating some diminutive hair shaft-like material within the keratotic spicules. Electron microscopic studies of a follicular lesion demonstrated extracellular viral particles suggestive of a polyomavirus within the central follicular keratotic debris. DNA Polymerase chain reaction (PCR) and gene sequencing studies, performed on the tissue of the microscopic slide and paraffin block, for the recently identified trichodysplasia spinulosa-associated polyomavirus (TSPyV), were resulted as positive for TSPyV. PCR for the Merkel cell polyomavirus (MCPyV) was negative. To date this case is unique in representing the first case of TS confirmed by electron microscopy in which a related viral pathogen has been molecularly identified. An additional 19 reported cases classifiable as TS are tabulated and reviewed.

The WT1 gene encodes a transcription factor implicated in normal and neoplastic development. The purpose of this study was to evaluate the diagnostic utility of a commercial WT1 antibody on a variety of pediatric small round blue cell tumors (SRBCT). A mouse monoclonal antibody (clone: 6F-H2, DAKO) raised against the N-terminal amino acids 1-181 of the human WT1 protein was tested. Microscopic sections from 66 specimens were stained using an antigen retrieval protocol with trypsin. The tumors included peripheral neuroectodermal tumors (PNET/Ewing's), neuroblastomas, desmoplastic small round cell tumors (DSRCT), lymphomas, Wilms' tumors, and rhabdomyosarcomas (RMS). One RMS case was investigated by Western blot analysis and RT-PCR to confirm the antibody specificity. A strong cytoplasmic staining was demonstrated in all RMS (11/11). The Western blot analysis confirmed the WT1 protein in the tissue, and the RT-PCR confirmed the presence of WT1 mRNA in the peripheral blood and tissue of one RMS patient. The Wilms' tumors had a variable nuclear and/or cytoplasmic positivity in most (17/24) cases. All PNET/Ewing's were negative. The nuclei of two lymphoblastic lymphomas stained strongly. A weak nuclear or cytoplasmic staining was reported in a few DSRCT (3/5), lymphomas (2/10), and neuroblastomas (2/8). This is a useful antibody in the differentiation of RMS from other SRBCTs. A strong cytoplasmic staining favors an RMS, and a strong nuclear staining is suggestive of a Wilms' tumor. A role for WT1 in the pathogenesis of rhabdomyosarcomas is raised. The limited sampling precludes any conclusions regarding the value of tissue or peripheral blood analysis for WT1 mRNA in patients with rhabdomyosarcoma. The WT1 gene (1) encodes a protein with four zinc fingers of the Kruppel-type in the C-terminal region that recognizes a guanidine-cytidine (GC)-rich "EGR1" consensus sequence (2) required in tissue differentiation and proliferation (2-4). The N-terminal half contains a large proline-glutaminerich domain important for inhibition of transcriptional activation (5, 6). There are at least eight protein isoforms ranging between 52 and 62 kDa in mammals produced by a combination of alternative splicing and RNA editing (4, 7). The WT1 proteins are normally expressed in the nuclei of glomerular podocytes and mesothelial cells. It has also been demonstrated in stem cells bearing the CD34ϩ phenotype (8). The role of WT1 in normal human development also extends to a diversity of mammalian mesodermal tissues (9), including the body-wall musculature in a 13.5-days postconception (dpc) mouse embryo (43-49 dpc human). Embryologic studies of wt1-null mice reveal a failure to develop kidney and gonads (10). Mutations and splicing disruptions of WT1 have been described in , WAGR (15), and Frasier (13,16) (17-22), mesothelial-derived neoplasms (23-27), breast cancer (28, 29), genitourinary tumors (30, 31), and small round blue cell tumors (SRBCT;24,27,(32)(33)(34). Recent studies have evaluated the possible role of peripheral blood RNA ...

The term “ancient” schwannoma was proposed for a group of neural tumors showing degenerative changes and marked nuclear atypia. Prior to the realization that the observed atypia was a regressive phenomenon, many of these lesions were erroneously diagnosed as sarcomas. Fine‐needle aspiration (FNA) cytologic material from five patients is included in this study. Tissue examined histologically included four resected tumors and 18 gauge core biopsies of one tumor. Aspirates of ancient schwannoma showed many of the same features as FNA of regular schwannoma: aggregates of spindled cells with indistinct cytoplasm and elongate nuclei with blunt point ends. The feature unique to these lesions was nuclear pleomorphism, which was identified in all aspirates. Nuclear inclusions were identified in all but one case. Cystic degeneration, xanthomatous changes, and perivascular sclerosis were identified in excised lesions. Ancient schwannomas show most of the FNA features of benign schwannomas but can demonstrate marked nuclear atypia. The FNA features of ancient schwannoma are important to note because of the potential to confuse this lesion with a more serious one such as sarcoma on FNA. Diagn. Cytopathol. 1999;20:307–311. © 1999 Wiley‐Liss, Inc.