Revealing the Precise Role of Calretinin Neurons in Epilepsy: We Are on the Way / 神经科学通报·英文版

Epilepsy is a common neurological disorder characterized by hyperexcitability in the brain. Its pathogenesis is classically associated with an imbalance of excitatory and inhibitory neurons. Calretinin (CR) is one of the three major types of calcium-binding proteins present in inhibitory GABAergic neurons. The functions of CR and its role in neural excitability are still unknown. Recent data suggest that CR neurons have diverse neurotransmitters, morphologies, distributions, and functions in different brain regions across various species. Notably, CR neurons in the hippocampus, amygdala, neocortex, and thalamus are extremely susceptible to excitotoxicity in the epileptic brain, but the causal relationship is unknown. In this review, we focus on the heterogeneous functions of CR neurons in different brain regions and their relationship with neural excitability and epilepsy. Importantly, we provide perspectives on future investigations of the role of CR neurons in epilepsy.

Nervus terminalis and nerves to the vomeronasal organ: a study using human fetal specimens / 대한해부학회지

The human nervus terminalis (terminal nerve) and the nerves to the vomeronasal organ (VNON) are both associated with the olfactory nerves and are of major interest to embryologists. However, there is still limited knowledge on their topographical anatomy in the nasal septum and on the number and distribution of ganglion cells along and near the cribriform plate of the ethmoid bone. We observed serial or semiserial sections of 30 fetuses at 7–18 weeks (crown rump length [CRL], 25–160 mm). Calretinin and S100 protein staining demonstrated not only the terminal nerve along the anterior edge of the perpendicular lamina of the ethmoid, but also the VNON along the posterior edge of the lamina. The terminal nerve was composed of 1–2 nerve bundles that passed through the anterior end of the cribriform plate, whereas the VNON consisted of 2–3 bundles behind the olfactory nerves. The terminal nerve ran along and crossed the posterior side of the nasal branch of the anterior ethmoidal nerve. Multiple clusters of small ganglion cells were found on the lateral surfaces of the ethmoid's crista galli, which are likely the origin of both the terminal nerve and VNON. The ganglions along the crista galli were ball-like and 15–20 µm in diameter and, ranged from 40–153 in unilateral number according to our counting at 21-µm-interval except for one specimen (480 neurons; CRL, 137 mm). An effect of nerve degeneration with increasing age seemed to be masked by a remarkable individual difference.

Ganglion cardiacum or juxtaductal body of human fetuses / 대한해부학회지

The ganglion cardiacum or juxtaductal body is situated along the left recurrent laryngeal nerve in the aortic window and is an extremely large component of the cardiac nerve plexus. This study was performed to describe the morphologies of the ganglion cardiacum or juxtaductal body in human fetuses and to compare characteristics with intracardiac ganglion. Ganglia were immunostained in specimens from five fetuses of gestational age 12–16 weeks and seven fetuses of gestational age 28–34 weeks. Many ganglion cells in the ganglia were positive for tyrosine hydroxylase (TH; sympathetic nerve marker) and chromogranin A, while a few neurons were positive for neuronal nitric oxide synthase (NOS; parasympathetic nerve marker) or calretinin. Another ganglion at the base of the ascending aorta carried almost the same neuronal populations, whereas a ganglion along the left common cardinal vein contained neurons positive for chromogranin A and NOS but no or few TH-positive neurons, suggesting a site-dependent difference in composite neurons. Mixtures of sympathetic and parasympathetic neurons within a single ganglion are consistent with the morphology of the cranial base and pelvic ganglia. Most of the intracardiac neurons are likely to have a non-adrenergic non-cholinergic phenotype, whereas fewer neurons have a dual cholinergic/noradrenergic phenotype. However, there was no evidence showing that chromogranin A- and/or calretinin-positive cardiac neurons corresponded to these specific phenotypes. The present study suggested that the ganglion cardiacum was composed of a mixture of sympathetic and parasympathetic neurons, which were characterized the site-dependent differences in and near the heart.

Differential Expression of Ca²⁺-buffering Protein Calretinin in Cochlear Afferent Fibers: A Possible Link to Vulnerability to Traumatic Noise

The synaptic contacts of cochlear afferent fibers (CAFs) with inner hair cells (IHCs) are spatially segregated according to their firing properties. CAFs also exhibit spatially segregated vulnerabilities to noise. The CAF fibers contacting the modiolar side of IHCs tend to be more vulnerable. Noise vulnerability is thought to be due to the absence of neuroprotective mechanisms in the modiolar side contacting CAFs. In this study, we investigated whether the expression of neuroprotective Ca²⁺-buffering proteins is spatially segregated in CAFs. The expression patterns of calretinin, parvalbumin, and calbindin were examined in rat CAFs using immunolabeling. Calretinin-rich fibers, which made up ~50% of the neurofilament (NF)-positive fibers, took the pillar side course and contacted all IHC sides. NF-positive and calretinin-poor fibers took the modiolar side pathway and contacted the modiolar side of IHCs. Both fiber categories juxtaposed the C-terminal binding protein 2 (CtBP2) puncta and were contacted by synaptophysin puncta. These results indicated that the calretinin-poor fibers, like the calretinin-rich ones, were afferent fibers and probably formed functional efferent synapses. However, the other Ca²⁺-buffering proteins did not exhibit CAF subgroup specificity. Most CAFs near IHCs were parvalbumin-positive. Only the pillar-side half of parvalbumin-positive fibers coexpressed calretinin. Calbindin was not detected in any nerve fibers near IHCs. Taken together, of the Ca²⁺-buffering proteins examined, only calretinin exhibited spatial segregation at IHC-CAF synapses. The absence of calretinin in modiolar-side CAFs might be related to the noise vulnerability of the fibers.

The distribution of calbindin-D28k, parvalbumin, and calretinin immunoreactivity in the inferior colliculus of circling mouse / 대한해부학회지

The circling mice with tmie gene mutation are known as an animal deafness model, which showed hyperactive circling movement. Recently, the reinvestigation of circling mouse was performed to check the inner ear pathology as a main lesion of early hearing loss. In this trial, the inner ear organs were not so damaged to cause the hearing deficit of circling (cir/cir) mouse at 18 postnatal day (P18) though auditory brainstem response data indicated hearing loss of cir/cir mice at P18. Thus, another mechanism may be correlated with the early hearing loss of cir/cir mice at P18. Hearing loss in the early life can disrupt the ascending and descending information to inferior colliculus (IC) as integration site. There were many reports that hearing loss could result in the changes in Ca²⁺ concentration by either cochlear ablation or genetic defect. However, little was known to be reported about the correlation between the pathology of IC and Ca²⁺ changes in circling mice. Therefore, the present study investigated the distribution of calcium-binding proteins (CaBPs), calbindin-D28k, parvalbumin, and calretinin immunoreactivity (IR) in the IC to compare among wild-type (+/+), heterozygous (+/cir), and homozygous (cir/cir) mice by immunohistochemistry. The decreases of CaBPs IR in cir/cir were statistically significant in the neurons as well as neuropil of IC. Thus, this study proposed overall distributional alteration of CaBPs IR in the IC caused by early hearing defect and might be helpful to elucidate the pathology of central auditory disorder related with Ca²⁺ metabolism.

A Case of Recurrent Myxomatous Corneal Degeneration Treated by Interferon Alpha-2b

PURPOSE: To report a case of recurrent myxomatous corneal degeneration after pterygectomy. CASE SUMMARY: A 65-year-old man with a history of abdominal keloid was referred to our hospital for assessment of a well-circumscribed, gelatinous, whitish corneal mass on the nasal corneal area of the left eye that appeared one month prior. The patient had undergone pterygectomy on his left eye 2 years ago. The patient experienced mild foreign body sensation. The other anterior segment and fundus examination of the left eye were both normal. We diagnosed the case as keloid and we performed excisional biopsy of the corneal mass. Histologic findings revealed proliferation of myxoid-appearing material in the anterior corneal stroma. On immunohistochemical examination, sections were stained positive for actin and calretinin, and negative for S-100. We diagnosed the tumor as myxomatous corneal degeneration. After six months, a recurrent mass was found on the previously excised site. Re-excisional biopsy and topical interferon α-2b treatment were then performed in response. After re-excision, there was no recurrence or complications during one year follow-up. CONCLUSIONS: Myxomatous corneal degeneration should be considered during differential diagnosis of an elevated, whitish, gelatinous lesion of the cornea with previous history of trauma or operation, such as pterygectomy. An interferon α-2b topical treatment is useful for recurrent corneal myomatous degeneration.

Giant solitary fibrous tumor of the pleura: A case report and literature review / 中南大学学报(医学版)

Solitary fibrous tumor (SFT) is a derived mesenchymal tumor from spindle cells, mostly occurred in the pleura. To analyze the clinical features of the SFT, data for a patient with SFT that involved in the pleura were retrospectively analyzed by assisted thoracoscope in the Affiliated Hospital of Zunyi Medical College in August 2015. The male patient was 45 years old, who showed the main clinical symptoms of chest pain, cough, sputum, and dyspnea. Large amount of right pleural effusion, chest space-occupying lesions were found by chest CT, suggesting a malignant tumor with metastasis at the 2nd and 3rd right rib. Immunohistochemical results showed: CD34 (+), cytokeratin (-), cytokeratin 5/6 (-), calretinin (-), epithelial membrane antigen(-), mesothelial cell (-), vimentin (++), Wilm's tumor-1 (+), Bcl-2 (+), CD56 (-), CD99 (+), desmin (-), and thyroid transcription factor-1 (-). It was diagnosed as SFT at right side wall layer pleura. SFT is a rare disease and it may occur at any site in the body. It lacks characteristic clinical symptoms and can be asymptomatic, or displays symptoms such as cough, chest pain, dyspnea, and hemoptysis. SFTs can only be conclusively diagnosed based on histopathologic and immunohistochemical characteristics of the tumor, and they are mostly benign. The main treatment for SFTs is the complete surgical resection. The prognosis for this disease is relatively good.

The Usefulness of Calretinin Immunohistochemistry for Rectal Suction Biopsy to Diagnose Hirschsprung’s Disease / 소아외과

PURPOSE: Hirschsprung’s disease (HD) is a congenital intestinal disorder with absence of ganglion cells in the intestinal muscle and submucosa. Diagnosis is based on histopathological study such as H&E, and acetylcholinesterase (AchE) immunohistochemistry. Calretinin immunohistochemistry was introduced as a new diagnostic method against limitations of other staining. The aim of this study is to investigate the usefulness of calretinin immunohistochemistry for the diagnosis of HD compared to H&E and AchE. METHODS: Ten patients with HD and 22 non-HD patients were included in the study. H&E staining, AchE and calretinin immunohistochemistry were performed in all 32 patients. All slides were evaluated by same single pathologist and the diagnostic value was calculated for each H&E stain, AchE immunohistochemical staining, and calretinin immunohistochemical staining. RESULTS: Calretinin method had sensitivity of 100% and specificity of 100% for diagnosis of HD. Its diagnostic accuracy was 100%. AchE staining showed 100% of specificity and 80% of sensitivity. Diagnostic accuracy of H&E staining was 56.3%. CONCLUSION: We concluded that calretinin immunohistochemistry is a very useful and valuable method to diagnosis HD patient.

Distribution of D1 and D2-dopamine receptors in calcium-binding-protein expressing interneurons in rat anterior cingulate cortex / 生理学报

Dopamine plays an important role in cognitive functions including decision making, attention, learning and memory in the anterior cingulate cortex (ACC). However, little is known about dopamine receptors (DAR) expression patterns in ACC neurons, especially GABAergic interneurons. The aim of the present study was to investigate the expression of the most abundant DAR subtypes, D1 receptors (D1Rs) and D2 receptors (D2Rs), in major types of GABAergic interneurons in rat ACC, including parvalbumin (PV)-, calretinin (CR)-, and calbindin D-28k (CB)-containing interneurons. Double immunofluorescence staining and confocal scanning were used to detect protein expression in rat brain sections. The results showed a high proportion of PV-containing interneurons express D1Rs and D2Rs, while a low proportion of CR-positive interneurons express D1Rs and D2Rs. D1R- and D2R-expressing PV interneurons are more prevalently distributed in deep layers than superficial layers of ACC. Moreover, we found the proportion of D2Rs expressed in CR cells is much greater than that of D1Rs. These regional and interneuron type-specific differences of D1Rs and D2Rs indicate functionally distinct roles for dopamine in modulating ACC activities via stimulating D1Rs and D2Rs.

Clinicopathologic features of fetal nuchal cystic hygroma: report of 40 cases / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the pathogenesis, pathologic features and prognosis of fetal nuchal cystic hygroma.</p><p><b>METHODS</b>Forty autopsied cases of fetal nuchal cystic hygroma were collected during January 2003 to December 2012. The clinical history, pathologic changes and immunohistochemical (EnVision method) findings were reviewed, and the pathogenesis and pathologic characteristics were analyzed.</p><p><b>RESULTS</b>Of the 40 cases, 16 (40.0%) showed single malformation and 24 (60.0%) were associated with multiple malformations in other organs and/or systems.Nineteen cases were septated and 21 were not. The associated malformations occurred in the respiratory system, skeletal system and urinary system.In the cases of combined malformations of umbilical cord, 3 were single umbilical artery malformations and 1 was torsion and stricture of umbilical cord.Four cases had chromosomal analysis, and all were trisomy-21.</p><p><b>CONCLUSIONS</b>Fetal nuchal cystic hygroma is a rare disease. The etiology is unknown, but it is not neoplastic.Lymphangioma is divided into 3 types:capillary lymphangioma, cavernous lymphangioma and cystic hygroma according to their expansile growth pattern. The overall prognosis is determined by any co-existing chromosomal anomalies, associated malformations and the time of diagnosis of the cystic hygroma.</p>

Nodular histiocytic/mesothelial hyperplasia: a clinicopathologic analysis of 7 cases / 中华病理学杂志

<p><b>OBJECTIVE</b>To analyze the clinicopathologic and immunohistochemical features of nodular histiocytic/mesothelial hyperplasia (NHMH) and to improve the knowledge of this disease.</p><p><b>METHODS</b>Seven cases of NHMH were collected and the clinicopathologic and immunohistochemical data were analyzed with review of the literature.</p><p><b>RESULTS</b>Seven male patients aged from 1.5 to 5.0 years (mean 2.8). The main clinical symptom was an inguinal mass.Grossly, main pathological changes were the mural nodule or free nodule in lumen, with diameter of 0.1-0.5 cm.Histologically, the tumor cell morphology was relatively single, cohesive polygonal or oval cells which were arranged in solid sheets or nests, usually with ovoid or deeply grooved nuclei and a moderate amount of pale pink cytoplasm in the nodular collection area. The nuclei had delicate chromatin and no obvious atypia, and mitosis was incidentally found. A few scattered lymphocytes were found in the stroma. The cyst wall was lined by a single layer of mesothelial cells.Immunohistochemically, the most cells in nodular lesion were strongly positive for the histiocytic marker CD68, vimentin and α1-antichymotrypsin, while lining mesothelial cells on the wall were positive for calretinin, MC, WT1, CK5/6, CKpan and EMA.</p><p><b>CONCLUSIONS</b>NHMH is a rare and benign tumor-like lesion, and easy to be misdiagnozed, which should be distinguished from neuroendocrine tumors, Langerhans cell histiocytosis, seminoma, mesothelioma and so on. The correct diagnosis of this lesion depends on the clinical characteristics, morphology and immunohistochemistry.</p>

The expression of α2A-adrenoceptors in the calcium-binding protein immunoreactive interneurons in rat prefrontal cortex / 生理学报

The α2A adrenoceptors (α2A-ARs) are the most common adrenergic receptor subtype found in the prefrontal cortex (PFC). It is generally accepted that stimulation of postsynaptic α2A-ARs on pyramidal neurons are key to PFC functions, such as working memory. However, the expression of α2A-ARs in interneurons is largely unknown. In the present study using double-labeling immunofluorencence technique, we investigated the expression of α2A-ARs in major types of rat PFC interneurons expressing calcium-binding proteins parvalbumin (PV), calretinin (CR), and calbindin (CB). Our data demonstrated that α2A-ARs are highly expressed in calcium-binding protein immunoreactive interneurons of rat PFC, suggesting that stimulation of α2A-ARs may alter neural networks comprising pyramidal neurons and interneurons, thereby exerting a beneficial effect on PFC cognitive functions. The present study provides the morphological basis for a potential mechanism by which stimulation of α2A-ARs induces cognitive improvement.

Pleural Mesothelioma: An Institutional Experience of 66 Cases

BACKGROUND: Malignant mesothelioma of the pleura is an aggressive tumor known to be associated with asbestos. Histological diagnosis of mesothelioma is challenging and is usually aided by immunohistochemical markers. METHODS: During an 18-year period (1995-2012), 66 patients with pleural mesothelioma were diagnosed at the Samsung Medical Center in Seoul. We reviewed hematoxylin and eosin and immunohistochemical slides of pleural mesothelioma and evaluated their pathological and clinical features. RESULTS: The male-to-female ratio was 1.75:1, and age of patients ranged from 28 to 80 years with an average age of 56.84 years. Twenty-two out of 66 patients underwent curative pneumonectomy. Follow-up data was available in 60 patients (90.9%), and 50 of them (83.3%) died from the disease. The average overall survival was 15.39 months. Histologically, the epithelioid type was the most common, followed by the sarcomatoid and the biphasic types. Epidemiologic information was not available in most cases, and only one patient was confirmed to have a history of asbestos exposure. CONCLUSIONS: Malignant mesothelioma of the pleura is a fatal tumor, and the therapeutic benefit of pneumonectomy remains unproven. The combination of calretinin, Wilms tumor 1, HMBE-1, and thyroid transcription factor-1 may provide high diagnostic accuracy in diagnosing mesothelioma.

Survival of calbindin, calretinin and parvalbumin positive neurons in mouse hippocampal CA area at chronic stage of pilocarpine-induced epilepsy / 中南大学学报(医学版)

OBJECTIVE@#To analyze the survival and the changes of proportions of Calbindin, Calretinin and Parvalbumin positive neurons in mouse hippocampal CA area at chronic stage of Pilocarpine-induced epilepsy.@*METHODS@#Calbindin, Calretinin and Parvalbumin immunofluoresence staining were done 2 months after Pilocarpine-induced epilepsy in mice or saline injection.@*RESULTS@#Two months after Pilocarine-induced epilepsy, the number of Calbindin, Calretinin and Parvalbumin positive neurons in the CA area decreased significantly compared with the control (P<0.01), especially the Calbindin positive neurons had a great drop and Pavalbumin positive neurons had a least drop. At the chronic stage of epilepsy, the proportion of Calbindin, Calretinin and Parvalbumin positive neurons in the CA area was changed. The content of Pavalbumin positive neurons increased whereas the content of Calbindin positive neurons decreased significantly compared with the control (P<0.01).@*CONCLUSION@#The changes of proportions of Calbindin, Calretinin and Parvalbumin positive neurons in the CA area of mouse hippocampus may be a factor in the ongoing epileptic activity at chronic stage of Pilocarpine-induced epilepsy.

Developmental Role of Anoctamin-1/TMEM16A in Ca2+-Dependent Volume Change in Supporting Cells of the Mouse Cochlea

Mammalian cochlea undergoes morphological and functional changes during the postnatal period, around the hearing onset. Major changes during the initial 2 postnatal weeks of mouse include maturation of sensory hair cells and supporting cells, and acquisition of afferent and efferent innervations. During this period, supporting cells in the greater epithelial ridge (GER) of the cochlea exhibit spontaneous and periodic activities which involves ATP, increase in intracellular Ca2+, and cell volume change. This Ca2+-dependent volume change has been proposed to involve chloride channels or transporters. We found that the spontaneous volume changes were eliminated by anion channel blocker, 100 microM NPPB. Among candidates, expression of Anoctamin-1 (Ano1 or TMEM16A), bestriphin-1 and NKCC1 were investigated in whole-mount cochlea of P9-10 mice. Immunolabeling indicated high level of Ano1 expression in the GER, but not of betrophin-1 or NKCC1. Double-labeling with calretinin and confocal image analysis further elucidated the cellular localization of Ano1 immunoreactivity in supporting cells. It was tested if the Ano1 expression exhibits similar time course to the spontaneous activities in postnatal cochlear supporting cells. Cochlear preparations from P2-3, P5-6, P9-10, P15-16 mice were subjected to immunolabeling. High level of Ano1 immunoreactivity was observed in the GER of P2-3, P5-6, P9-10 cochleae, but not of P15-17 cochleae. Taken together, the localization and time course in Ano1 expression pattern correlates with the spontaneous, periodic volume changes recorded in postnatal cochlear supporting cells. From these results we propose that Ano1 is the pacemaker of spontaneous activities in postnatal cochlea.

Ovarian steroid cell tumor, not otherwise specified: a clinicopathologic study / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the clinicopathologic features, diagnostic criteria, differential diagnosis and treatment options of ovarian steroid cell tumor, not otherwise specified (NOS).</p><p><b>METHODS</b>Light microscopy and immunohistochemical study was carried out in 8 cases of ovarian steroid cell tumor, NOS. The literature was reviewed.</p><p><b>RESULTS</b>The 7 cases of benign ovarian steroid cell tumor, NOS were composed mainly of polygonal cells with granular eosinophilic cytoplasm and larger cells with vacuolated cytoplasm. They resembled the architecture of normal adrenal gland, with formation of cell nests and trabeculae. The single case of malignant ovarian steroid cell tumor had evidence of significant cellular pleomorphism, haemorrhage and coagulative tumor necrosis. The mitotic count measured about 7 per 10 high-power fields. Immunohistochemical study showed that the tumor cells expressed calretinin and alpha-inhibin. Differential diagnosis included oxyphilic granulosa cell tumor, thecoma, Sertoli cell tumor and clear cell carcinoma. The treatment options of benign ovarian steroid cell tumor, NOS was local excision or ipsilateral salpingo-oophorectomy, while the malignant counterpart should be treated with a combination of surgery and chemotherapy, including administration of GnRH agonist.</p><p><b>CONCLUSIONS</b>Ovarian steroid cell tumor, NOS, is the most common type of ovarian steroid cell tumors. Most of which are associated with a benign clinical outcome. Immunohistochemistry is an important adjunct for diagnosis. The treatment options of ovarian steroid cell tumor, NOS depend on its malignant potential.</p>

The Diagnostic Utility of Mesothelial Markers in Distinguishing between Reactive Mesothelial Cell and Adenocarcinoma Cells in Serous Effusions with Cytospin Preparation / 대한세포병리학회지

Evaluation of serous effusions can include immunocytochemical stains that differentiate reactive mesothelial cell from adenocarcinoma cell. Among several positive mesothelial cell markers, we used desmin, CK5/6, WT1 and calretinin all known to have high sensitivity and specificity as selective mesothelial cell markers. We studied smears obtained with cytospin from 15 malignant and eight benign effusions. The mesothelial cells were positively stained by desmin, CK5/6, WT1 and calretinin in 60.9%, 29.1%, 26.7% and 56.5%, respectively among 8 benign and 15 malignant effusions; the adenocarcinoma cells were positively stained 6.7%, 13.3%, 1.0% and 0.0%, respectively among 15 malignant effusions. The percentage of positively stained mesothelial cells were somewhat lower for all antibodies compared to the results of previous studies. This was likely due to the differences in preparation methods and fixatives among studies. In conclusion, the use of desmin and calretinin were more valuable than CK5/6 and WT1 for distinguishing between reactive mesothelial cell and adenocarcinoma cells in serous effusion; however, choice of the proper preparation methods and fixatives are also important

Adenomatoid Tumor of the Testis with Infiltration to the Seminiferous Tubules / 대한비뇨기과학회지

A 41-year-old man presented a bean sized, solid, painless left scrotal mass he'd had for 10 years. The mass was well demarcated and it showed homogeneous echogenecity on ultrasonography. Simple mass excision was performed and the specimen revealed a relatively well circumscribed mass lesion composed of dilated tubules with flattened lining cells. A focal infiltration to the seminiferous tubule and involvement of the biopsy margins were observed. The tubules had a positive reaction to the calretinin and anti-mesothelial antibody on immunohistochemical stain. Therefore, the tumor was diagnosed as adenomatoid tumor of the testis. Adenomatoid tumors of testis are rare benign neoplasms that are thought to originate from mesothelum. Most cases were reported in the epididymis, spermatic cord and testicular tunica, and rare cases were from the ejaculatory duct, prostate and adrenal gland. The findings of adenomatoid tumor infiltrating through the testis parenchyme and seminiferous tubule, like for our case, have not been previously reported in Korea.

Well Differentiated Papillary Mesothelioma of the Ovarian Surface: A Case Report

Well differentiated papillary mesothelioma (WDPM) is an unusual variant of epithelial mesothelioma. Most WDPMs exhibit either benign or indolent behavior. Making the differential diagnosis between this rare tumor and serous papillary carcinoma can be problematic. We report here on a case of a 43-year-old woman with a WDPM of the surface. She presented to our hospital for a routine gynecologic evaluation, and she had no specific symptoms or a history of asbestos exposure. Gynecologic ultrasonography revealed a right ovarian mass that measured 6 x 3.8 x 3 cm in size. No ascites was detected. Right salpingo-oophorectomy was performed; grossly, the tumor was a yellowish firm, multinodular mass. Microscopically, the tumor consisted of numerous papillae that were lined by a single layer of uniform mesothelial cells. Nuclear pleomorphism and mitoses were not found. On immunohistochemical study, the tumor cells were positive for calretinin and cytokeratin, but they were negative for CEA. It is important to differentiate WDPM from serous papillary carcinoma or other malignant tumors to avoid treating them as malignant tumors.