Hirose, Takanori

Deletion (DL) of chromosome 1p is common in oligodendroglial (OLG) tumors and is prognostically significant. We studied 1p DL (FISH method) and morphologic/ultrastructural (EM)/immunohistochemical (IHC) features of OLG, in 22 tumors. Six of 12 gr II, 6 of 8 gr III and 1 of 2 gr IV tumors were 1p DL. On EM, all tumors contained round cells with lucent to organelle (Golgi, mitochondria, microtubules)‐rich cytoplasm and few or no intermediate filaments (IF); 3 features (myelin figures, whorls of IF, synapses) suggested OLG, astrocytic and neuronal status, respectively. OLG features were seen in 3 DL gr II OLG, 2 nondeleted (NDL) gr II and in 1 NDL gr III tumor. Astrocytic feature was seen in 2 DL gr II, 4 DL gr III, and in all 9 NDL tumors. Neuronal features were seen in 3 DL gr II OLG, 2 NDL gr II and in 1 NDL gr III tumor. Overall, the 3 phenotypes were present in 23 , 46 and 23 % in of DL OLGs and in 44, 100 and 33 % of NDL tumors, respectively. IHC for synaptophysin (SYN), neurofilament protein (NFP), chromogranin, and Neu N were performed. Reactivity(s) were noted in 77% of all tumors, 71% of pure OLG, 100% of mixed tumors, 69% of DL tumors, and 89% of NDL tumors. Neu‐N and SYN were most often seen. Of all tumors with OLG, astrocytic and/or neuronal EM, 86, 71 and 83% showed staining, respectively. In summary, a) ND is common in OLG, both pure and mixed, and b) OLG tumors with and without a glioneuronal EM +/− IHC phenotype may both be 1p DL. Mayo Clinic funded.

Malignant nerve sheath tumors involving cranial nerves are rare. We identified 13 cases of MCNST arising in cranial nerve or from benign nerve sheath tumors, all but three being intracranial. The patients included 10 males and 3 females, one pediatric (5 years) and the remainder ranging in age from 23 to 69 years (mean, 40). The vestibular (n=5) and vagal nerves (n=3) were favored sites, followed by posterior fossa (n=2), facial nerve (n=1), frontal lobe parenchyma (n=1) and the lateral ventricle (n=1). Some patients were known to have NF1(n=3) or probable NF2 (n=1). Three tumors arose in transition from a conventional schwannoma and one from a plexiform neurofibroma. The majority of the tumors (n=11) were high grade (5 WHO III and 6 WHO IV) lesions. Immunohistochemistry was performed in 11 cases; S‐100 protein reactivity was diffuse (n=1), partial (n=2), focal (n=5) or negative (n=3). Collagen IV was also diffuse (n=2), partial (n=3), focal (n=5) or negative (n=1). p53 protein staining was high (n=7), moderate (n=2), or low (n=2). Clinical follow‐up was available in 10 cases; of the 8 patients who died, six patients did so within six months of surgery, and two within three years. Only one tumor, a grade IV MCNST with heterologous bone formation, developed extensive spinal leptomeningeal drop metastases. The one pediatric patient is alive at 8 years. No clinically apparent systemic metastases were encountered.

AbstractPrimary CNS lymphoma (PCNSL) is a rare diffuse large B-cell lymphoma originating within the central nervous system. The overall incidence of PCNSL is rising, particularly in the elderly population. Immunosuppression is a strong risk factor, but most patients with this tumor are apparently immunocompetent. Diagnosis of PCNSL can be challenging. Non-invasive or minimally invasive tests such as ophthalmological evaluation and spinal fluid analysis may be useful, but the majority of patients require tumor biopsy for definitive diagnosis. Our knowledge concerning optimum treatment of PCNSL is fragmentary due to paucity of adequately sized trials. Most patients are now initially treated with high-dose-methotrexate-based chemotherapy alone, as the addition of whole-brain radiotherapy at standard doses has not been shown to increase survival and does increase the risk of neurological toxicity. Ongoing trials are addressing issues such as the roles of reduced-dose radiotherapy, the addition of the CD20 antibody rituximab to chemotherapy, high-dose chemotherapy followed by autologous stem cell transplantation, and maintenance therapy in the primary management of PCNSL.

We describe two examples of soft tissue perineurioma, a hard tumor, 1.7 cm in diameter, involving the dermis and superficial subcutaneous tissue of the left thumb, and the other a massive, lobulated lesion of the pelvis. Both occurred in 49-year-old men. Both were mobile and well demarcated but unencapsulated. Their cut surfaces were white and collagenous. Microscopically, each consisted of spindle-shaped or epithelioid tumor cells in a dense stroma of haphazardly oriented collagen bundles. Spindle-shaped cells were individually distributed, whereas epithelioid cells were often arranged in cords or clusters. Cytologic atypia was conspicuous in the massive tumor, but no mitotic activity was observed. Immunostains showed diffuse reactivity for vimentin, membrane pattern staining for epithelial membrane antigen and type IV collagen, as well as patchy CD34 reactivity. Stains for S-100 protein, Leu-7, smooth muscle actin, desmin, and cytokeratin were negative. Ultrastructural studies showed perineurial cell characteristics, including slender cytoplasmic processes, numerous pinocytotic vesicles, occasional tight junctions, and discontinuous surface basement membrane. Perineuriomas featuring marked stromal sclerosis often occur in the hands of young adults, as has recently been reported; the authors considered it a clinicopathologic variant. Herein we report two sclerotic perineuriomas, one a small tumor of the thumb and the other a centrally situated, massive pelvic tumor with sclerosis and degenerative cytologic atypia. We believe that exaggerated collagen deposition in perineuriomas, occasionally associated with degenerative nuclear changes, is not a manifestation of a unique, clinically relevant tumor variant but rather a manifestation of chronicity akin to that seen in “ancient schwannoma” and ‘atypical neurofibroma.’