Search for a Novel Allergen in Hen's Egg Allergy Using an IgE Immunoblotting Assay.

BACKGROUND: Food allergy is a serious health issue affecting roughly 4% of children, with a substantial effect on quality of life. Chicken egg allergy is frequently observed in infants. Therefore, some of them have to exclude hen's eggs from their daily diet to avoid allergenic symptoms. Hen's egg is composed of 2 soluble parts; one is egg white, which has been characterized as the major source of allergenicity, while the other is egg yolk, which is estimated as a miner source. Only 2 allergens from egg yolk, α-livetin (Gal d 5) and YGP42 (Gal d 6), have been described to date. METHODS: Sera from 53 patients allergic to hen's eggs and 2 patients allergic to sesame were obtained from the Department of Pediatrics, Chiba University Hospital. The study was performed using SDS-PAGE, IgE immunoblotting, and dot blotting. RESULTS: Seven bands of egg yolk were detected by IgE immunoblotting. Out of these bands, a possible new allergen was further characterized by LC-MS/MS. The 33-kDa band was identified as yolk glycoprotein (YGP40) by LC-MS/MS. A total of 21 of the 53 patients (47%) had YGP40 detected by dot blotting. CONCLUSIONS: We identified YGP40 as a new hen's egg yolk allergen and detected 4 sites of YGP40 as linear epitopes.

Enhanced neurogenesis and possible synaptic reorganization in the piriform cortex of adult rat following kainic acid-induced status epilepticus.

Epileptic seizure has been reported to enhance adult neurogenesis and induce aberrant synaptic reorganization in the human dentate gyrus in the hippocampal formation. However, adult neurogenesis in the extrahippocampal regions has not been well studied. To investigate seizure-enhanced neurogenesis in the extrahippocampal regions, we performed histological and immunohistochemical as well as western blot analyses on the cerebrum of Sprague-Dawley rats (n = 51, male, 7 weeks old, body weight 250-300 g) treated with intraperitoneal injection of kainic acid (KA, 10 mg/kg) to induce status epilepticus (SE) (n = 36) or normal saline solution (n = 15) followed by 5'-bromo-2-deoxyuridine (BrdU) injection to label newborn cells. Even though severe neuronal damage was found in the piriform cortex of rats having SE, immunohistochemistry for double cortin (DCX) revealed an increase in the number of immature neurons in the piriform cortex. Double immunofluorescence staining demonstrated that DCX-positive cells in the piriform cortex were positive for both BrdU and neuronal nuclear antigen. Immunohistochemistry and western blotting revealed increased expressions of synaptophysin and postsynaptic density protein 95 in the piriform cortex of rat having SE. These results suggested the enhanced neurogenesis and possible synaptic reorganization in the piriform cortex of the KA-treated rat.

Demonstration of Mitochondrial Damage and Mitophagy in Cisplatin-Mediated Nephrotoxicity.

Cisplatin is a chemotherapeutic widely used in the treatment of various types of solid tumors. Acute kidney injury is the most critical dose-limiting factor in cancer patients treated with cisplatin; mitochondrial dysfunction and resultant cell damage by reactive oxygen species released from damaged mitochondria are suspected to be involved in the kidney injury. Pathological features of mitochondrial damage in relation to cisplatin-mediated nephrotoxicity, however, is not fully described. The purpose of this study was to demonstrate mitochondrial damage and clearance of damaged mitochondria by mitophagy in cisplatin-mediated nephrotoxicity. Three groups of rats received a single intraperitoneal injection of cisplatin at 20 mg/kg and were sacrificed at 24, 48 and 72 hours after the treatment. A time-dependent increase in the number of damaged renal tubules and the serum levels of blood urea nitrogen, creatinine, and mitochondrial aspartate transaminase was observed in rats after the treatment. We showed the increased numbers of swollen and fragmented mitochondria, observed by electron microscopy, and of cytochrome c oxidase IV- and 8-nitroguanosine-positive intracytoplasmic granules, detected by immunohistochemistry, in the degenerated renal tubules of the treated animals. Moreover, activated autophagy process was indicated in the degenerated renal epithelial cells, based on the findings of immunohistochemistry of microtubule-associated protein 1 light chain 3 (LC3), an autophagy marker, and lysosomal-associated membrane protein 1 (LAMP-1), a lysosome marker, and swollen and fragmented mitochondria in autophagosomes. These results suggest that mitochondrial damage and clearance of damaged mitochondria by mitophagy is involved in cisplatin-mediated nephrotoxicity.

Physiological effects of brominated flame retardants on NC/Nga mice.

PURPOSE: Brominated flame retardants (BFRs) are used as an additive or reactive components in various materials. Regarding their health concerns, their immunotoxicity have not been clarified yet. MATERIALS AND METHODS: In the current study, we examined the effects of systemic exposure to two types of BFRs, DE71 and DE79, on pathophysiologic traits of murine atopic dermatitis (AD). Male NC/Nga mice were repeatedly injected intraperitoneally with DE71 and DE79 and/or mite allergen (Dermatophagoides pteronyssinus: Dp) into their right ears. Thereafter, clinical scores, macroscopic findings of inflammatory foci, and Ig values in serum were examined. RESULTS: Both DEs significantly aggravated clinical scores induced by mite allergen including skin dryness and edema. Total IgE titer was significantly greater in the Dp + DE79 group than in the Dp group. CONCLUSIONS: Taken together, exposure to BFRs can exacerbate AD-like skin lesions related to mite allergen in mice. The accentuating effects may be mediated, at least in part, through hyperproduction of IgE.

A Pathological Study of Acute Pulmonary Toxicity Induced by Inhaled Kanto Loam Powder.

The frequency and volume of Asian sand dust (ASD) (Kosa) are increasing in Japan, and it has been reported that ASD may cause adverse respiratory effects. The pulmonary toxicity of ASD has been previously analyzed in mice exposed to ASD particles by intratracheal instillation. To study the pulmonary toxicity induced by inhalation of ASD, ICR mice were exposed by inhalation to 50 or 200 mg/m³ Kanto loam powder, which resembles ASD in elemental composition and particle size, for 6 h a day over 1, 3, 6, 9, or 15 consecutive days. Histological examination revealed that Kanto loam powder induced acute inflammation in the whole lung at all the time points examined. The lesions were characterized by infiltration of neutrophils and macrophages. The intensity of the inflammatory changes in the lung and number of neutrophils in both histological lesions and bronchoalveolar lavage fluid (BALF) appeared to increase over time. Immunohistochemical staining showed interleukin (IL)-6- and tumor necrosis factor (TNF)-α-positive macrophages and a decrease in laminin positivity in the inflammatory lesions of the lung tissues. Electron microscopy revealed vacuolar degeneration in the alveolar epithelial cells close to the Kanto loam particles. The nitric oxide level in the BALF increased over time. These results suggest that inhaled Kanto loam powder may induce diffuse and acute pulmonary inflammation, which is associated with increased expression of inflammatory cytokines and oxidative stress.

Excitatory amino acid transporter 2 downregulation correlates with thalamic neuronal death following kainic acid-induced status epilepticus in rat.

Recurrent seizures without interictal resumption (status epilepticus) have been reported to induce neuronal death in the midline thalamic region that has functional roles in memory and decision-making; however, the pathogenesis underlying status epilepticus-induced thalamic neuronal death is yet to be determined. We performed histological and immunohistochemical studies as well as cerebral blood flow measurement using 4.7 tesla magnetic resonance imaging spectrometer on midline thalamic region in Sprague-Dawley rats (n = 75, male, 7 weeks after birth, body weight 250-300 g) treated with intraperitoneal injection of kainic acid (10 mg/kg) to induce status epilepticus (n = 55) or normal saline solution (n = 20). Histological study using paraffin-embedded specimens revealed neuronal death showing ischemic-like changes and Fluoro-Jade C positivity with calcium deposition in the midline thalamic region of epileptic rats. The distribution of neuronal death was associated with focal loss of immunoreactivity for excitatory amino acid transporter 2 (EAAT2), stronger immunoreaction for glutamate and increase in number of Iba-1-positive microglial cells showing swollen cytoplasm and long processes. Double immunofluorescence study demonstrated co-expression of interleukin-1 beta (IL-1ß) and inducible nitric oxide synthase (iNOS) within microglial cells, and loss of EAAT2 immunoreactivity in reactive astrocytes. These microglial alterations and astrocytic EAAT2 downregulation were also observed in tissue without obvious neuronal death in kainic acid-treated rats. These results suggest the possible role of glutamate excitotoxicity in neuronal death in the midline thalamic region following kainic acid-induced status epilepticus due to astrocytic EAAT2 downregulation following microglial activation showing upregulation of IL-1ß and iNOS.

Effects of hydrogen peroxide on mucociliary transport in human airway epithelial cells.

The effects of environmental pollutants on airway clearance have not been well elucidated. This study examined mucociliary transport using different sized-fluorescent particles on polarized human airway epithelial cells which were maintained in an air-liquid interface (ALI) culture system. The effects of hydrogen peroxide (H2O2) exposure on mucociliary transport were also investigated. The movement of fluorescent particles with diameters of 10-14 and 2.5-4.5 µm was observed by fluorescent microscopy as an index of the mucociliary transport. The mixture of the particles with two different sizes was propelled concentrically on the apical surface by the interaction of ciliary activity and mucus in the control condition, whereas H2O2 exposure for 24 h significantly inhibited the movement of the particles. The particle sizes did not affect their movement after the control or H2O2 exposure. These results suggest that particle tracking on polarized human airway epithelial cells is a useful experimental tool for the evaluation of the effect of environmental pollutants on mucociliary transport. In addition, reactive oxygen species may impair mucociliary transport, leading to the airway damage and exacerbation of respiratory diseases.

Caveolae-mediated endocytosis of intratracheally instilled gold colloid nanoparticles at the air-blood barrier in mice.

Endocytosis is the primary mechanism by which nanoparticles are translocated over the alveolar epithelium. The purpose of this study was to elucidate the association between endocytosis and the translocation of nanoparticles at the air-blood barrier (ABB). Gold colloid particles (diameter, 20 nm) were intratracheally instilled into male ICR mice. Fifteen minutes after instillation, localized accumulation of agglomerated gold particles was observed in the cytoplasm of macrophages, on the surface of alveolar epithelial cells (AECs), and in alveoli. Electron microscopy revealed particles in the vesicles of macrophages, on the surface of AECs, and in caveolae-like vesicles in type 1 AECs. Immunohistochemistry demonstrated positive immunolabeling for caveolin-1 in the ABB of untreated lungs as well as lungs treated with gold particles. Double immunofluorescence and immunoelectron microscopy revealed the presence of caveolin-1 in AECs in the untreated lungs. These results suggest that instilled gold colloid particles are internalized into the alveolar epithelium at the ABB by caveolae-mediated endocytosis, which is regarded as a physiological function of AECs.

Vanadium toxicity in mice: possible impairment of lipid metabolism and mucosal epithelial cell necrosis in the small intestine.

Because precise information as to the toxicity of vanadium is required for practical use of vanadium compounds as antidiabetic drugs, we examined vanadium toxicity in mice fed normal diet or high-fat diet (C57BL/6N, male, 7 weeks) by oral administration of ammonium metavanadate (AMV) with a maximum dose of 20 mgV/kg/day. Marked lipid accumulation in hepatocytes, renal epithelial cells, and mucosal epithelial cells of the small and large intestines and severe degeneration, necrosis, and loss of mucosal epithelial cells in the small intestine were observed. These pathological changes were more severe in mice fed high-fat diet than mice fed normal diet, and the intensity of the changes increased with increase in the administered dose of AMV. By electron microscopy, the number and size of lipid droplets in hepatocytes were increased. In the small intestine, a TUNEL assay showed a decreased number of positive cells, and positive cells for acrolein immunohistochemistry were observed specifically in the mucosal epithelial cells indicating degeneration and necrosis in the AMV-treated group, suggesting that a possible factor responsible for cell necrosis in the small intestine could be oxidative stress. In conclusion, AMV may impair cellular lipid metabolism, resulting in lipid accumulation, and induce mucosal epithelial cell necrosis in the small intestine.

Pathological study of chronic pulmonary toxicity induced by intratracheally instilled Asian sand dust (kosa).

Asian sand dust (ASD) events are associated with an increase in pulmonary morbidity and mortality. The number of ASD events has increased rapidly in the east Asian region since 2000. To study the chronic lung toxicity of ASD, saline suspensions of low doses (200 and 400 µg) and high doses (800 and 3,000 µg) of ASD were intratracheally instilled into ICR mice. Animals were sacrificed at 24 hr, 1 week, or 1, 2, or 3 months after instillation. Histopathological examination revealed that ASD induced acute inflammation at 24 hr after instillation. The acute inflammation was transient and subsided at 1 week and 1 month after instillation. At 2 and 3 months after instillation, focal infiltration of lymphocytes with accumulation of epithelioid macrophages, which is a suggestive finding of transformation to granuloma, and granuloma formation were occasionally observed. Aggregation of macrophages containing particles was observed in the pulmonary lymph nodes at 3 months after instillation in high-dose groups. Prolonged inflammatory foci (granuloma) and presence of ASD particles in pulmonary lymph nodes would have a chance to induce immunological modulation leading to adverse health effects in the exposed animals.

Pathological study of acute pulmonary toxicity induced by intratracheally instilled Asian sand dust (kosa).

The objective of this study was to investigate acute lung toxicity caused by Asian sand dust. Simulated Asian sand dust collected from the Tennger desert in China (CJ-2 particles) and Asian sand dust collected from the atmosphere in Japan (Tottori particles) were used. Saline suspensions of 50, 200, 800, and 3,000 µg Asian sand dust were intratracheally instilled to ICR mice. Localized accumulation of the dust particles was observed in the bronchioles and the alveoli of the lung tissues; acute inflammatory changes characterized by infiltration of macrophages and neutrophils were observed around the particles. Degenerated alveolar walls and bronchial epithelial cells, as well as a weakened positive immunolabeling for laminin, were observed to be associated with particle attachment. Positive immunolabelings for interleukin-6, tumor necrosis factor-α inducible nitric oxide synthase, and dimeric copper- and zinc-containing superoxide dismutase were observed mainly in the inflammatory cells in the lesions; these findings were not observed in the controls or in areas lacking lesions. These results suggest that Asian sand dust particles caused damage to the lung tissue through a direct physical effect. In addition, secondary released cytokines and oxidative stress generated in the lesion may be involved in the development of the acute lung toxicity.

Experimental Scuticociliatosis in Japanese flounder (Paralichthys olivaceus) infected with Miamiensis avidus: pathological study on the possible neural routes of invasion and dissemination of the scuticociliate inside the fish body.

Japanese flounder (Paralichthys olivaceus) were experimentally infected with the highly pathogenic scuticociliate Miamiensis avidus (syn. Philasterides dicentrarachi) using the immersion method to clarify/identify the possible neural routes of entry and possible ways of dissemination of the scuticociliate in the fish body. Scuticociliates were observed on the skin and gills right from day 0-1 post-infection, muscle tissue on day 2 post-infection, reached the brain, and spinal cord on day 3 post-infection, and systemic infection was prominent afterwards. Brain lesions were observed in most of the examined fish from days 3 and 4 post-infection and considered to be the cause of the sudden increase in mortality. Affected fish showed varying degrees of tissue damage including severe epidermal and dermal necrotic lesions, necrotic myositis, encephalitis and myelitis. Whereas, scuticociliates were frequently observed along the optic and/or olfactory nerve in the fish which were accompanied by severe brain lesions but by minimum lesions in the gills and skin, suggesting that in addition to skin and/or gills, neural routes including periorbital and nasal routes may play a role in scuticociliate invasion to the brain. Scuticociliates were also observed in the peripheral nerve fibers in the muscle tissue, cranial and spinal nerves, cranial cavity and in the vertebral canal, suggesting that nerve fibers and/or cerebrospinal fluid circulation may be involved in the spread of the scuticociliate throughout the body in addition to the blood circulation and connective tissue.

Pathological study on the scuticociliatosis affecting farmed Japanese flounder (Paralichthys olivaceus) in Japan.

Pathological findings associated with scuticociliatosis in farmed Japanese flounder in Japan are described. Ten moribund fishes, farmed in Tottori Prefectural Fisheries Experimental Station, showed cutaneous ulcers, darkened skin, fin and tail rot, exophthalmia and alterations in swimming behaviour. Histopathologically, severe epidermal degeneration and necrosis, hyperplasia of branchial epithelium, myositis, myelitis, encephalitis associated with heavy accumulation of scuticociliates in the periorbital cavity and optic nerve fiber were observed. Moreover, masses of ciliates were found to feed on the host tissues such as skeletal muscles, gills and brain, causing severe degenerative changes associated with abundant neutrophilic and lymphocytic infiltration. These findings suggest that the present scuticociliate, Miamiensis avidus, is a highly invasive and destructive pathogen infecting Japanese flounder and capable of developing systemic fatal infection.

Pathogenesis of liver lesions in Theileria orientalis-inoculated cattle and severe combined immunodeficiency mice with bovine erythrocyte transfusion.

Theileria orientalis (T. orientalis) is a bovine protozoal disease similar to malaria in humans. Although the common outcome of malaria in humans and T. orientalis infection in cattle is hepatic disorder, the mechanisms of its development remain unknown. In this study, we investigated hepatocyte injury characterized by accumulation of macrophages with ingested erythrocytes in sinusoid and extramedullary hematopoiesis in cattle and mice experimentally infected with T. orientalis (T. orientalis-infected cattle and T. orientalis-infected mice). Vacuolization of hepatic cells was frequently observed in the vicinity of the aggregated macrophages in the liver sinusoids of T. orientalis-infected mice. A significant percentage of the macrophages accumulated in the liver sinusoids of the severely infected cattle and mice (14.6% and 24.2 to 53.2%, respectively) reacted positively with interleukin-1, interleukin-6 and TNF-α antibodies. Increase in the production of these cytokines was confirmed in T. orientalis-infected cattle and mice by real-time RT-PCR. These findings strongly suggest that increased cytokine production by the macrophages that have phagocytosed T. orientalis-infected erythrocytes causes hepatic disorder in T. orientalis-infected animals.

Urinary trypsin inhibitor protects against liver injury and coagulation pathway dysregulation induced by lipopolysaccharide/D-galactosamine in mice.

Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used for patients with inflammatory disorders including disseminated intravascular coagulation, shock, and pancreatitis in Japan. Our recent studies using UTI-null (-/-) mice have shown that UTI protects against systemic inflammatory responses and acute lung injury. However, the role of UTI in liver injury has not been elucidated. This study determined the contribution of UTI to liver injury and coagulatory disturbance induced by lipopolysaccharide and D-galactosamine (LPS/D-GalN) using UTI (-/-) and wild-type (WT) mice. LPS/D-GalN treatment caused severe liver injury characterized by neutrophilic inflammation, hemorrhagic change, necrosis, and apoptosis, which was more prominent in UTI (-/-) than in WT mice. In both genotypes of mice, LPS/D-GalN challenge caused elevations of aspartate amino-transferase and alanine amino-transferase, prolongation of the prothrombin and activated partial thromboplastin time, and decreases in fibrinogen and platelet counts, as compared with vehicle challenge. These changes, however, were significantly greater in UTI (-/-) than in WT mice. Circulatory levels of tumor necrosis factor (TNF)-alpha (P<0.05) and interferon (IFN)-gamma were also greater in UTI (-/-) than in WT mice after LPS/D-GalN challenge. These results suggest that UTI protects against severe liver injury and subsequent coagulatory disturbance induced by LPS/D-GalN, which was mediated, at least partly, through the suppression of TNF-alpha production along with its antiprotease activity.

Size effects of latex nanomaterials on lung inflammation in mice.

Effects of nano-sized materials (nanomaterials) on sensitive population have not been well elucidated. This study examined the effects of pulmonary exposure to (latex) nanomaterials on lung inflammation related to lipopolysaccharide (LPS) or allergen in mice, especially in terms of their size-dependency. In protocol 1, ICR male mice were divided into 8 experimental groups that intratracheally received a single exposure to vehicle, latex nanomaterials (250 microg/animal) with three sizes (25, 50, and 100 nm), LPS (75 microg/animal), or LPS plus latex nanomaterials. In protocol 2, ICR male mice were divided into 8 experimental groups that intratracheally received repeated exposure to vehicle, latex nanomaterials (100 microg/animal), allergen (ovalbumin: OVA; 1 microg/animal), or allergen plus latex nanomaterials. In protocol 1, latex nanomaterials with all sizes exacerbated lung inflammation elicited by LPS, showing an overall trend of amplified lung expressions of proinflammatory cytokines. Furthermore, LPS plus nanomaterials, especially with size less than 50 nm, significantly elevated circulatory levels of fibrinogen, macrophage chemoattractant protein-1, and keratinocyte-derived chemoattractant, and von Willebrand factor as compared with LPS alone. The enhancement tended overall to be greater with the smaller nanomaterials than with the larger ones. In protocol 2, latex nanomaterials with all sizes did not significantly enhance the pathophysiology of allergic asthma, characterized by eosinophilic lung inflammation and Igs production, although latex nanomaterials with less than 50 nm significantly induced/enhanced neutrophilic lung inflammation. These results suggest that latex nanomaterials differentially affect two types of (innate and adaptive immunity-dominant) lung inflammation.

Translocation pathway of the intratracheally instilled C60 fullerene from the lung into the blood circulation in the mouse: possible association of diffusion and caveolae-mediated pinocytosis.

Ultrafine particles are ubiquitous in ambient urban and indoor air from multiple sources and may contribute to adverse respiratory and cardiovascular diseases. Recently, it has been demonstrated that ultrafine particles (UFPs) are translocated from the lung into the systemic circulation. The exact pathway, however, for the translocation in the lung remains unclear. In this study, we examined the translocation pathway of intratracheally instilled C60 fullerene particles from the lung into the blood circulation in the mouse. Using light microscopy, aggregated particles of fullerene were observed in the capillary lumen in the lung and the pulmonary lymph nodes immediately after instillation. Electron microscopic analysis demonstrated an increased number of pinocytotic vesicles (caveolae) of various sizes in the type 1 alveolar epithelial cells (AEC) and endothelial cells; occasional caveolae containing some particulate substances were observed. In addition, particles of various sizes were observed throughout the structure of the air-blood barrier (ABB). These findings suggest that fullerene particles may pass the ABB by both diffusion and caveolae-mediated pinocytosis, resulting in immediate translocation into the systemic circulation.

Metallothionein as an anti-inflammatory mediator.

The integration of knowledge concerning the regulation of MT, a highly conserved, low molecular weight, cystein-rich metalloprotein, on its proposed functions is necessary to clarify how MT affects cellular processes. MT expression is induced/enhanced in various tissues by a number of physiological mediators. The cellular accumulation of MT depends on the availability of cellular zinc derived from the diet. MT modulates the binding and exchange/transport of heavy metals such as zinc, cadmium, or copper under physiological conditions and cytoprotection from their toxicities, and the release of gaseous mediators such as hydroxyl radicals or nitric oxide. In addition, MT reportedly affects a number of cellular processes, such as gene expression, apoptosis, proliferation, and differentiation. Given the genetic approach, the apparently healthy status of MT-deficient mice argues against an essential biological role for MT; however, this molecule may be critical in cells/tissues/organs in times of stress, since MT expression is also evoked/enhanced by various stresses. In particular, because metallothionein (MT) is induced by inflammatory stress, its roles in inflammation are implied. Also, MT expression in various organs/tissues can be enhanced by inflammatory stimuli, implicating in inflammatory diseases. In this paper, we review the role of MT of various inflammatory conditions.

Distribution of the inflammatory lesions in the central nervous system of dogs affected with disseminated and ocular form of granulomatous meningoencephalomyelitis.

An aged Maltese dog (dog 1) showed gait ataxia for a month and suddenly died after convulsion. An aged Toy Poodle dog (dog 2) showed sudden blindness with unresponsive pupillary light reflexes and sudden death due to acute cardiac failure. Histological examination of the two dogs demonstrated severe granulomatous perivascular inflammation in the white matter throughout the central nervous system (CNS) including the brain and spinal cord. Based on the clinical and pathological findings, these dogs were diagnosed as granulomatous meningoencephalomyelitis (GME). In dog 2, the inflammatory changes predominated in the visual system such as the optic nerve, optic tract and optic radiation in the cerebrum (ocular form). Distribution pattern of the inflammatory lesions in the CNS was compared between the two dogs.

Lymphoepithelial thymoma characterized by proliferation of spindle cells in a Samoyed dog.

Lymphoepithelial thymoma was diagnosed in a 14-year-old Samoyed dog with clinical symptoms of myasthenia gravis at 6 months of age. At necropsy, dark red-colored mass with many nodular protuberances was found in the anterior mediastinal area. Histologically, the mass consisted of solid proliferation of neoplastic cells with spindle nuclei and cytoplasm and a few lymphocytes, which is separated by an abundant fibrous and adipose tissue. Immunohistochemically, spindle cells were positive for cytokeratin, and infiltrating lymphocytes were positive for CD3. On the basis of these findings, this tumor was diagnosed as lymphoepithelial thymoma, which is morphologically similar to type A thymoma in humans.