Misa Iijima

An unusual variant of ependymoma with extensive tumor cell vacuolization

Abstract We report a case of ependymoma with unusual vacuolar features arising in the left occipital lobe of a 2-year-old child. The tumor was composed of cells with single or multiple cytoplasmic vacuoles and clear cells. Some cells showed a signet ring-like configuration. Clear cells were compactly arranged and showed an oligodendroglioma-like appearance. In addition, there were cellular ependymoma-like areas including perivascular pseudorosettes. On immunohistochemistry, glial fibrillary acidic protein and vimentin were mainly detected in cytoplasmic processes, and epithelial membrane antigen (EMA) staining showed granular and small vesicular reactivity. Ultrastructural investigation demonstrated intercellular microrosettes with or without cilia and long zonula adherens-type junctions that are typical of ependymoma. Furthermore, many intracytoplasmic lumina (ICL) were observed. Some ICL had microvilli and some did not. The latter varied in size, and may have fused with each other to develop giant ICL which could correspond to the signet ring-like configuration. Small ICL without microvilli had an appearance similar to that of distended endoplasmic reticula. Serial semithin and ultrathin sections revealed that EMA-positive structures were consistent with ICL containing microvilli and intercellular microrosettes. To determine the presence of unusual vacuolated ependymoma, electron microscopical examination was required. However, light microscopy was useful for detecting EMA-positive microvesicular and granular structures.

Human choroid plexus is an uniquely involved area of the brain in amyloidosis: a histochemical, immunohistochemical and ultrastructural study

To better understand the characteristics of amyloid deposition in the choroid plexus, we examined autopsied brain by routine histology, immunohistochemistry, and electron microscopy in three group of patients: primary systemic amyloidosis (n = 7), cerebral amyloid angiopathy (CAA, n = 6), and controls (n = 3). Three of the CAA patients had Alzheimers disease. Congophilic, birefringent amyloid deposits of the choroid plexus were seen in six of the seven cases of systemic light chain amyloidosis. Immunohistochemistry revealed that the deposited amyloids had reactivity for immunoglobulin light chain and amyloid P component. Accumulation of macrophages labeled with monoclonal antibodies against CD 68 and major histocompatibility complex class II antigens were observed around the massive amyloid deposits. The presence of approximately 10 nm amyloid fibrils along the epithelial basement membrane as well as in the vascular walls was ascertained by electron microscopy. In CAA, Congo red-positive amyloid deposits were consistently present in meningeal blood vessels and were often found in senile plaques of the cerebral parenchyma; congophilic amyloid deposits were absent in the choroid plexus. Choroid plexus epithelial cells exhibited immunostaining for beta amyloid precursor protein (APP) with N-terminal- and C-terminal-specific antibodies; in particular, consistent staining was obtained for the latter antibody. Immunoreactivity for amyloid beta protein (A beta) with monoclonal antibodies (6E10, 4G8) was often found in choroid plexus epithelial cells. These findings suggest that amyloid deposition of the choroid plexus depends on the major component protein in amyloidosis, and that the choroid plexus may produce APP and A beta protein although A beta amyloidosis is not evident in the choroid plexus.

Pale islands in medulloblastoma consist of differentiated cells with low growth potential

Cerebellar medulloblastomas are the most common embryonal neoplasms occurring in the pediatric age group. Thirty‐five specimens from 28 cases of medulloblastoma and variant neoplasms were examined to elucidate the histopathologic significance of the reticulin‐free pale islands. In 10 specimens, there were light‐looking areas corresponding to pale islands: three specimens from desmoplastic and seven from classic medulloblastoma. The difference in cell population, 1.73‐fold more cells in dark areas than in light areas (P< 0.001), seemed to be a major factor in the formation of the biphasic architecture. Immunohistochemically, occasional tumor cells in both areas were found to express neuronalphenotypes. In addition, positive immunoreactivity for glial markers was exceptional. There was significant difference in the staining indices (SI) for cell proliferation markers. The light areas consistently showed low SI values (mean MIB‐1 SI, 5.75; mean PCNA SI, 11.8) compared with the dark areas (mean MIB‐1 SI, 22.7; mean PCNA SI, 44.9). It is suggested that light areas (pale islands) consist of more differentiated cells of neuronal lineage with relatively low proliferation potential. These tumor cells might proliferate in a group, and then expand, thereby compressing the surrounding tissue to form pale islands.

Infectious mononucleosis lymphadenitis resembling Kikuchi's disease: Cytological, histopathological, and immunohistological findings.

Kikuchi’s disease (KD) is a benign self-limited disease, most frequently seen in young Asians, with painless cervical lymphadenopathy and systemic symptoms such as fever.1 The characteristic cytological findings of KD include tingible body macrophages with crescent-shaped nuclei, prominent karyorrhectic nuclei and the absence of neutrophils.2-4 The causative agents of KD remain unknown. However, Epstein-Barr virus (EBV)-encoded mRNA (EBER) was found in a few cases by in situ hybridization (ISH)1, 5 Here, we report, here, cytological, histopathological, and immunohistochemical findings of a case of infectious mononucleosis (IM) resembling KD. A 40-year-old Japanese woman presented with bilateral cervical lymphadenopathy. A lymph node biopsy was performed and she was tentatively diagnosed with malignant lymphoma. Laboratory studies demonstrated a white blood cell count of 5.260/mm3 with lymphocytosis of 45% including 3% atypical forms, a slightly elevated LDH level (245 <229 IU/L), and moderately abnormal liver function tests: ALT (74 <27 IU/L) and AST (125<47 IU/L). Subsequent serologic tests for EBV showed the following results: a viral capsid antigen (VCA) IgG titer of 0.2 (normal range <1), VCA IgM titer of 0.6 (normal range <0.5), and an antigen (EBNA) titer of 0.1(normal range <0.5). There was no further treatment administered, and the patient was well at the last follow-up two months later. Cytological examination of the imprint smears demonstrated a polymorphic lymphoid cell population, including numerous tingible body macrophages, and isolated or small clusters of epithelioid cells (Fig.1). No macrophages with crescent nuclei were observed in the smear. The majority of the lymphoid cells were small to medium-sized lymphocytes with scattered large transformed lymphocytes and immunoblasts (Fig.1). On Giemsa staining of a smear, the immunoblasts had round nuclei with fine nuclear chromatin, and large central nucleoli, and relatively broad basophilic cytoplasm. Some of them had a perinuclear halo (Fig. 2). Moreover, mature plasma cells, binucleated plasma cells, and cells with plasma cell differentiation were also intermingled with these cells. The epithelioid cells had an oval or elongated vesicular nuclei, and abundant amphophilic cytoplasm (Fig. 1). The lesion contained only a few neutrophils. Histologically, in a low-power field, the lesion contained a focally coagulative necrotic area (Fig. 2). Lymphoid follicles were not prominent. In a high-power field, the lesion was composed of small to medium-sized lymphocytes, large transformed lymphocytes, immunoblasts, tingible body macrophages, epithelioid cells, cells with plasma cell differentiation, and plasma cells (Fig. 5). CD3 and CD20 immunostain demonstrated the mixed natures of large transformed lymphocytes and immunoblasts. CD15 immunostain demonstrated only a few neutrophils. Scattered myeloperoxidase-positive Infectious mononucleosis lymphadenitis resembling Kikuchis disease: Cytological, histopathological, and immunohistological findings.