Neurocysticercosis in a Japanese woman with lung cancer who repeatedly visited endemic countries.

BACKGROUND: Taenia solium, present in most developing countries, infects many individuals and may result in their death. Neurocysticercosis (NCC) develops after invasion of the brain by parasitic larvae. It is the most common parasitic disease of the human central nervous system. On imaging scans it can be similar to brain tumors. We report a patient with a metastatic brain tumor and NCC. The co-presence of NCC was diagnosed based on specific neuroimaging- and epidemiologic findings. CASE PRESENTATION: A 36-year-old non-smoking Japanese woman with a history of non-small-cell lung cancer had undergone resection of the lower lobe followed by cytotoxic chemotherapy 2 years before apparently suffering recurrence. A positron emission computed tomography (PET) scan incidentally revealed multiple intracranial cold spots exhibiting differences in their shape and size. On brain magnetic resonance imaging (MRI) scans we observed many different patterns of peripheral edema and gadolinium-enhancing effects. As she had often visited Latin America and Southeast Asia and had eaten raw pork and Kimchi, we suspected that the brain lesions were due to NCC rather than metastatic brain tumors. However, serum immunoblotting assay and DNA analysis were negative for T. solium. Rather than performing resection, we administered albendazole (ABZ) and dexamethasone because her earlier cytotoxic chemotherapy had elicited severe pancytopenia. Except for a single large lesion in the left frontal lobe, this treatment resulted in a significant reduction in the size of these lesions and a decrease in perilesional edema. She underwent resection of the residual lesion 10 months later. Histology revealed it to be a metastatic tumor. Polymerase chain reaction (PCR) assay for NCC was negative. In the course of 11-months follow-up there has been no recurrence. CONCLUSION: This is the first presentation of NCC in a Japanese woman with a metastatic brain tumor. NCC was incidentally discovered on PET scans and, based on her travel history and epidemiological findings; it was diagnosed and successfully treated with ABZ. NCC is endemic in most developing countries and as visits to such countries have increased, NCC must be ruled out in patients with multiple cystic nodular brain lesions.

Adult-onset atypical teratoid/rhabdoid tumor featuring long spindle cells with nuclear palisading and perivascular pseudorosettes.

Atypical teratoid/rhabdoid tumors (AT/RTs) are rare malignant neoplasms of the CNS that preferentially affect young children. We herein report an adult case of AT/RT surviving for more than 5 years with the residual tumor. The patient, a 24-year-old man at onset, presented with a contrast-enhancing mass lesion in the left occipital lobe, and underwent partial tumor resection. Histologically, the tumor was predominantly composed of long spindle cells exhibiting nuclear palisading and perivascular pseudorosettes, which appeared to mimic mesenchymal, ependymal and Schwann cell tumors. A small number of isolated rhabdoid cells did not initially attract attention, and a tentative pathological diagnosis of a malignant mesenchymal tumor was made. In a later examination focusing on the small areas of rhabdoid cells, the extensive loss of the nuclear expression of INI1 was detected in all areas. Diffuse staining with vimentin and focal immunoreactivity for epithelial membrane antigen and alpha smooth muscle actin were observed not only in AT/RT foci, but also in spindle cell areas. Thus, polyphenotypic immunoreactivity was evident. Fluorescence in situ hybridization revealed a homozygous deletion of chromosome 22q covering the INI1 locus. Histopathological differences between infant and adult AT/RTs currently remain unclear. In the case of a malignant adult brain tumor showing a hardly classifiable morphology and immunophenotypic diversity, an analysis of the INI1 status may contribute to an accurate diagnosis.

Failure rates of Asian-type anatomic medullary locking stemmed metal-on-metal total hip replacement: A cause for adverse tissue reactions to metal debris (ARMD).

BACKGROUND: Adverse tissue reaction to metal debris (ARMD) as a secondary complication of Metal-on-metal total hip replacement (MoM THR) has been of concern. We have been performing cementless MoM THR using an Asian-type anatomic medullary locking (AML) stem. The purpose of this study is to examine the incident rate of ARMD, and the implant survival rate. METHODS: The study included 187 patients (211 hip joints) who underwent MoM THR between February 2007 and November 2009 at our hospital and who were followed up for a minimum of 6 years. The cases included 174 female joints and 37 male joints. The average age at the time of surgery was 68.4 years. The average postoperative follow-up period was 87.5 months. RESULTS: ARMD was observed in 23 joints postoperatively, and the incidence rate was 10.9%. Most of the instances occurred within the first 30 months postoperatively. Revision surgery was performed for 14 joints after conservative treatment failed, and we changed the bearing surface. During the intraoperative observation, black-colored deposition of metal debris on the head-neck junction was observed in 13 cases. Kaplan-Meier analysis using the replacement surgery as the end point showed that this implant has a survival rate of 93.8% 7 years after the primary surgery. CONCLUSIONS: We conclude that the major cause of failure of Asian-type AML stemmed MoM THR is likely the breakage of the fixation between the taper neck and metal head at the head-neck junction.

Marked cardiomegaly in a patient with familial amyloidotic polyneuropathy after orthotopic liver transplantation: a case study.

Hepatocyte-derived mutant amyloidogenic transthyretin (ATTR) causes familial amyloidotic polyneuropathy (FAP), for which orthotopic liver transplantation is an established curative treatment. However, some patients with FAP have cardiac amyloidosis after transplantation. Here, we describe a man with an autonomic disorder diagnosed as FAP ATTR Val30Met and marked cardiomegaly after liver transplantation. He underwent orthotopic liver transplantation at 49 years of age and was prescribed prednisolone to prevent graft rejection. Two years later, autonomic dysfunction and severe heart failure gradually developed. He died suddenly at 59. The autopsy revealed marked cardiomegaly (heart weight: 1020 g). Histological and ultrastructural examinations demonstrated massive amyloid deposition and unusual myocardial hypertrophic injury associated with nuclear translocation of the glucocorticoid receptor (GR). No other FAP patients without heart failure showed GR nuclear translocation. GR is a nuclear transcription factor that leads to myocardial hypertrophy, and cumulative prednisolone doses may promote marked cardiomegaly and severe cardiac amyloidosis.

Primary anaplastic pleomorphic xanthoastrocytoma with widespread neuroaxis dissemination at diagnosis--a pediatric case report and review of the literature.

We report a 5 year-old boy with primary anaplastic pleomorphic xanthoastrocytoma (PXA) with whole neuroaxis dissemination at diagnosis who experienced the sudden onset of generalized convulsion. Head- and spinal magnetic resonance imaging (MRI) showed widespread gadolinium (Gd)-enhanced lesions extending to the bilateral frontal- and medial temporal lobes and the spinal cord. Subsequent MRI study demonstrated that the lesion size increased without any neurological deterioration. Under a histopathologic diagnosis of anaplastic PXA he underwent adjuvant chemotherapy consisting of 12 cycles of carboplatin and vincristine. The patient is alive without any neurological deficits; follow-up MRI showed that the lesions remained stable during 18 months of chemotherapy. We report a very rare pediatric case of primary anaplastic PXA with dissemination involving the entire neuroaxis at the time of diagnosis.

Overexpression of IGF2 and IGF2 receptor in malignant solitary fibrous tumor with hypoglycemia: a case report.

BACKGROUND: Solitary fibrous tumor (SFT) is a prototypical mesenchymal neoplasm that induces non-islet cell tumor hypoglycemia (NICTH) due to overproduction of insulin-like growth factor 2 (IGF2). We here report the case of a malignant SFT associated with a hypoglycemia attack. CASE PRESENTATION: An 81-year-old man with a large subphrenic mass presented with hypoglycemia and loss of consciousness. His serum insulin and IGF1 levels were relatively low, suggesting an excessively high serum IGF2 levels. Preoperative Western blotting of serum confirmed the overproduction of high-molecular-weight IGF2. After total tumor resection, the patient recovered from hypoglycemia without the need for further treatment. Histological examination revealed proliferation of spindle cells and frequent nuclear mitoses with STAT6 and CD34 immunoreactivity, which led to the diagnosis of malignant SFT. IGF2 was strongly upregulated in the tumor upon immunohistochemistry, consistent with the report of NICTH. In addition, the tumor expressed IGF2 receptor (IGF2R) but not IGF1R. CONCLUSIONS: The present results indicate that the tumor co-expressed IGF2 and IGF2R. IGF2R has not previously been recognized as a tyrosine kinase receptor participating in cell signal transduction. Thus, further case series are required to determine whether IGF2R overexpression reflects the action of an unknown autocrine/paracrine system involving IGF2 for cell proliferation or for the scavenging and degradation of IGF2.

Omental torsion.

A 65-year-old man presented to the emergency department complaining of right lower abdominal pain. Abdominal computed tomography showed a whirling pattern of fatty streaks and vessels in the greater omentum. From this typical finding, a diagnosis of omental torsion was made immediately, which was confirmed by subsequent surgery. We report a case of surgically and pathologically proven omental torsion that demonstrated a typical appearance on computed tomography and was diagnosed preoperatively.

Oxidized LDL in carotid plaques and plasma associates with plaque instability.

OBJECTIVE: Oxidation of LDL plays a significant pathogenic role in atherosclerosis. In this study, we attempted to clarify the correlation between the morphology of human atherosclerotic plaques and the oxidized LDL (OxLDL) levels in plasma and carotid plaques. METHODS AND RESULTS: OxLDL levels (ng/microg apolipoprotein B) in plasma and carotid plaques from 44 patients undergoing carotid endarterectomy and OxLDL levels in 17 control plasma and 9 normal intima samples were determined by a sandwich ELISA by using specific antibodies against OxLDL (DLH3) and apolipoprotein B. The plaques were immunohistochemically classified as macrophage (Mphi)-rich and Mphi-poor. In paired samples from individual patients, plaque OxLDL was nearly 70 times higher than plasma OxLDL (mean+/-SEM, 11.9+/-1.7 vs 0.18+/-0.01 ng/microg apoB, P<0.0001). The OxLDL level was significantly higher in Mphi-rich- than Mphi-poor plaques (19.6+/-2.8 vs 5.50+/-0.77 ng/microg apoB, P<0.0001) and corresponded with DLH3 antigen positivity of the plaques. In patients with Mphi-rich plaques, plasma OxLDL was significantly higher than in the controls (0.20+/-0.02 vs 0.13+/-0.01 ng/microg apoB, P=0.02). CONCLUSIONS: Our results suggest that LDL undergoes further oxidation in plaques, and that high plasma and plaque levels of OxLDL are correlated with the vulnerability to rupture of atherosclerotic lesions.

Cytoplasmic expression of fibroblast growth factor receptor-4 in human pituitary adenomas: relation to tumor type, size, proliferation, and invasiveness.

The pathogenesis of pituitary adenomas remains unknown. A pituitary tumor-derived (ptd) isoform of fibroblast growth factor receptor-4 (ptd-FGFR4) has been implicated in the neoplastic process. To further understand the expression of FGFR4 in sporadic human pituitary adenomas, we studied 137 pituitary adenomas of various types (102 adenomas from Japanese patients and 35 adenomas from Canadian patients) and 10 nontumorous pituitaries using a polyclonal antiserum that recognizes the C terminus of FGFR4 and analyzed possible relationships among expression of FGFR4, patient nationality, tumor type, size, invasion, and the labeling index of the proliferation marker Ki-67 using the MIB-1 antibody. Cytoplasmic expression of FGFR4 protein was observed in 57.8% of Japanese cases and 62.8% of Canadian cases. FGFR4 reactivity was absent in all 10 normal adenohypophysial tissues examined. FGFR4 expression in pituitary adenomas was restricted mainly to the cytoplasm, a pattern similar to that seen in rat pituitary cells transfected with human ptd-FGFR4 but different from that of cells transfected with wild-type FGFR4, which displayed membrane localization of staining. Protein from primary human adenomas migrated as a 65-kDa species consistent with the predicted size of ptd-FGFR4. FGFR4 protein expression was frequently found in adenomas containing GH, ACTH, or FSH/LH and was also found in null cell adenomas, but reactivity was relatively rare in prolactin-containing adenomas in both Japanese and Canadian groups. The expression of FGFR4 protein was stronger in macroadenomas than in microadenomas (P = 0.02) and high levels of FGFR4 expression (moderate or greater density staining) were more frequently observed in macroadenomas than in microadenomas (P < 0.05). High levels of FGFR4 expression also correlated significantly with the proliferation marker Ki-67 (P = 0.002) and tended (but not significantly) to be found in invasive tumors. These data are consistent with a role for ptd-FGFR4 in pituitary tumorigenesis in a majority of human pituitary adenomas. Moreover, detection of FGFR4 cytoplasmic staining may provide an ancillary diagnostic tool in the diagnosis of pituitary adenoma, particularly in equivocal cases.

Clinicopathological significance of lipid peroxidation in carotid plaques.

Several reports have suggested an association between lipid peroxidation and human carotid atherosclerosis, but few reports have demonstrated a link between lipid peroxidation and carotid plaques in humans. In this study, we investigated the relationship between clinical features, histopathological characteristics and lipid peroxidation in patients undergoing carotid endarterectomy (CEA). Forty-one carotid plaques were obtained. A portion of the most severe lesions was subjected to histopathologic examination, and the remainder of the plaques examined for lipid peroxidation. Thiobarbituric acid-reactive substances (TBARS) values were determined as a marker for lipid peroxidation. The lipid-rich core (LC) and macrophage infiltration (Mphi) component as a percentage of total plaque area were measured morphometrically. Based on the results, all plaques were classified into four groups. Group I (GI): LC <10%; Group IIa (GIIa): LC 10-30%, Mphi <5%; Group IIb (GIIb): LC 10-30%, Mphi < or = 5%, and Group III (GIII): LC < or =30%. The plaque TBARS values of GIII were significantly higher than those of GI, GIIa, and GIIb. The TBARS values of GIIb were one-and-a-half times higher than those of GIIa. Our results show that lipid peroxidation in carotid plaques is significantly associated with carotid atherosclerosis, especially plaque instability. These findings provide direct evidence of an association between lipid peroxidation and human atherosclerosis.

Morules with optically clear nuclei in ovarian borderline endometrioid tumor.

Optically clear nuclei (OCN) have been observed in morules of some neoplasms and in some conditions unrelated to the development of the morules. We first report a case of ovarian borderline endometrioid tumor (BET) showing the morules associated with OCN. The patient was a 47-year-old premenopausal woman with a left ovarian cystic tumor, atypical endometrial hyperplasia, and elevated serum levels of FSH, LH, estradiol, and CA 125. The resected ovarian tumor measured 6 cm in diameter, and showed a papillary growth. Histologically, the ovarian tumor was consistent with BET, and the morules with OCN were scattered. Immunohistochemically, OCN were proven to be rich in biotin. An aberrant nuclear expression of beta-catenin was observed in both the tumor cells and the morular cells. Our case may suggest the possibility that the appearance of OCN with or without morules in ovarian tumors is related to endometrioid differentiation of the tumor cells, and should be recognized as a diagnostic clue of ovarian endometrioid tumors. Although female sex hormones have been reported to play a role in the occurrence of OCN, the participation of beta-catenin mutation has also been suggested.

Alterations of E-cadherin, alpha-catenin and beta-catenin expression in neuroendocrine tumors of the gastrointestinal tract.

Neuroendocrine tumors (NETs) of the gastrointestinal tract comprise a heterogeneous group of neoplasms arising from the diffuse neuroendocrine system. These tumors strongly differ from each other on the basis of different pathogenetic, clinical, functional, histological, and prognostic patterns. Previous studies have shown that abnormal and reduced expression of the E-cadherin/catenin complex in several human cancers is associated with tumor dedifferentiation, advanced clinical stages, and poor survival rate. We assessed correlations between the expression of E-cadherin and catenins, Ki-67, and the following clinicopathological factors: age, embryological site of origin, size, histological growth pattern, the depth of penetration into the intestinal wall, and the presence of metastasis. In this study, reduction of membranous E-cadherin expression to a variable degree was detected in more than two-thirds (42 of 51) of gastrointestinal NETs (19 foregut, 8 midgut, and 24 hindgut) belonging to the complete neuroendocrine neoplastic spectrum [18 well-differentiated NETs, 22 well-differentiated neuroendocrine carcinomas (NECs), and 11 poorly differentiated NECs]. The reduction of E-cadherin expression was concomitant with the reduction of alpha-catenin (44 of 51) and beta-catenin (35 of 51) expression. Our immunohistochemical analysis demonstrated significant differences of percentage of membranous positive cells of E-cadherin, alpha-catenin, or beta-catenin between normal tissues and well-differentiated NETs (P=0.0038, P=0.004, and P=0.0329, respectively), well-differentiated NECs (P<0.001, P<0.001, and P<0.001, respectively) and poorly differentiated NECs (P=0.0002, P<0.0002, and P=0.0002, respectively). Among the gastrointestinal NETs, there were significantly more positive cells of E-cadherin, alpha-catenin, or beta-catenin in well-differentiated NETs than well-differentiated NECs (P=0.0006, P=0.0065, and P=0.0001, respectively) or poorly differentiated NECs (P=0.0053, P=0.0041, and P<0.001, respectively). MIB-1 labeling index generally showed a low proliferative activity in well-differentiated NETs (0.49+/-0.37) and well-differentiated NECs (0.662+/-0.66). A high proliferation rate was observed in poorly differentiated NECs (41.518+/-16.59). MIB-1 labeling index was significantly higher in poorly differentiated NECs than well-differentiated NETs and well-differentiated NECs (P<0.0001 and P<0.0001, respectively). E-cadherin, alpha-catenin, and beta-catenin expression were correlated significantly with transmural tumor invasion (P<0.0001, P=0.0001, and P<0.0001, respectively) and with size (P=0.0013, P=0.0001, and P<0.0001, respectively). These results indicate that the alteration in the E-cadherin/catenin expression may be involved in the growth and progression of gastrointestinal NETs.

Von Hippel-Lindau disease.

Von Hippel-Lindau (VHL) disease is an uncommon, autosomal dominant hereditary multitumor syndrome caused by germline alterations of the VHL gene, which has been cloned recently and identified as a tumor suppressor gene. The major lesions in VHL disease include hemangioblastomas in the central nervous system and retina, clear cell renal cell carcinomas, pheochromocytomas, pancreatic tumors, epididymal cystadenomas, endolymphatic sac tumors, carcinoid tumors, and multiple cysts of the kidney, pancreas, and epididymis. Compared with sporadic ones, the tumors in VHL disease develop at an earlier age and often multifocally. Histologic features of VHL tumors are characterized by their high degree of vascularization and the presence of a clear cell component. Hypervascularization is induced by overexpression of vascular endothelial growth factor (VEGF), and because the principal function of VHL protein is the negative regulation of hypoxia-inducible mRNAs including VEGF mRNA, inactivation of VHL gene plays critical roles in angiogenesis of the VHL tumors. In addition, since VHL protein is also required for the down-regulation of transcription activity of certain genes for the cell growth and cell cycle, inactivation of VHL gene may contribute to tumorigenesis of the VHL tumors. A significant difference in the frequency of types of VHL gene mutation has been noted among the affected families, known as the genotype-phenotype correlations.

Subependymoma of the spinal cord and review of the literature.

Subependymoma is a tumor of the central nervous system, which frequently occurs in the ventricles and rarely in the spinal cord. Most of the intraventricular subependymomas are subclinical and thus incidentally encountered at autopsy, whereas the spinal ones are inevitably accompanied by myelopathy and are often diagnosed clinically as ependymomas or astrocytomas. Two cases of spinal cord subependymomas are reported, one of which recurred 9 years after the initial operation. All specimens of both cases showed similar microscopic features. Within a highly fibrillary background, round to ovoid tumor cells were unevenly distributed and arranged in cell clusters. Mitoses were rarely encountered. No necrosis was demonstrated in any of the specimens. Ultrastructural examination demonstrated many slender processes containing abundant intermediate filaments and occasional small lumen-like structures with many microvillous projections and cell junctions. Subependymomas arising in the spinal cord should be distinguished from other more aggressive gliomas, such as diffuse astrocytomas and ependymomas. Characteristic microscopic features and the ultrastructural studies support the diagnosis.

Growing teratoma syndrome in a patient with a non-germinomatous germ cell tumor in the neurohypophysis--case report.

A 16-year-old woman presented with a non-germinomatous germ cell tumor in the neurohypophysis manifesting as progressive visual disturbance, amenorrhea, hydrodipsia, and polyuria. Her serum alpha-fetoprotein and human chorionic gonadotropin levels were elevated. She experienced sudden, rapid visual deterioration and underwent emergency partial tumor removal to decompress the optic nerves. Her vision subsequently improved. Histological examination of the surgical specimens confirmed immature teratoma. She received chemotherapy (ifosphamide 900 mg/m2, cisplatin 20 mg/m2, etoposide 60 mg/m2) for 5 consecutive days. Although the tumor marker levels decreased remarkably, her vision again declined rapidly due to enlargement of the tumor after the first course of chemotherapy. A second radical operation resulted in vision improvement. The tumor specimen showed only mature teratoma elements. This phenomenon, called the growing teratoma syndrome, is very rare in intracranial non-germinomatous germ cell tumors.

Neurocutaneous melanosis associated with malignant leptomeningeal melanoma in an adult: clinical significance of 5-S-cysteinyldopa in the cerebrospinal fluid---case report.

A 35-year-old male presented with a variant of neurocutaneous melanosis with leptomeningeal malignant melanoma. He had three pigmented nevi from birth. He suffered diplopia followed by headache. T1-weighted magnetic resonance (MR) imaging revealed hydrocephalus and a small linear hyperintense lesion in the right frontal cortex. Several parts of the cortical sulci and the brain surface were slightly enhanced by gadolinium. Ventriculoperitoneal shunting was performed and extensive pigmented leptomeninges were recognized. Open biopsy established the diagnosis of leptomeningeal malignant melanoma. Combined chemoimmunotherapy was repeated every other month with monitoring of the 5-S-cysteinyldopa (5-S-CD) level in the cerebrospinal fluid (CSF). The 5-S-CD level decreased after each treatment, but the basal level steadily increased prior to the next treatment. Two years after the onset, he showed paraplegia caused by an extramedullary mass at the T-6 level. MR imaging showed that melanoma had involved the entire subarachnoid space including the whole spine. He underwent emergent removal of the spinal tumor and showed transient marked improvement. Further intensive chemotherapy was given. However, he died 31 months after the onset of massive proliferation of intracranial leptomeningeal melanoma. Measurement of CSF 5-S-CD levels is valuable for evaluating the therapeutic efficacy and for monitoring the progression of melanoma.

Thrombospondin-1 is highly expressed in desmoplastic components of invasive ductal carcinoma of the breast and associated with lymph node metastasis.

Desmoplastic (scirrhous) invasion and lymph node metastasis are critical for the treatment and prognosis of invasive ductal carcinoma of the breast. Despite being an anti-angiogenic therapeutic candidate, Thrombospondin-1 (TSP-1) promotes invasion and metastasis of some carcinomas. To clarify the effect of TSP-1 on invasion and metastasis, we obtained 101 invasive ductal carcinomas of the breast with axillary lymph node resection. All tumors were histologically divided into two categories, carcinomas with, and those with non- /minimal desmoplastic component. Immunohistochemistry for TSP-1 was performed on all primary tumors and axillary lymph nodes with tumor metastasis. Fifty-four (53.5%) of 101 tumors were recognized as positive for TSP-1 in the cytoplasm of tumor cells. Histological study showed that significantly more cancers with desmoplastic components (46/69, 66.7%) manifested TSP-1 expression than did cancers with no- or minimal (less than 20%) desmoplasia (8/32, 25.0%; p<0.001). Axillary lymph node metastasis was significantly higher in TSP-1-positive- (28/54, 51.9%) than TSP-1-negative cancers (11/47, 23.4%; p<0.005). The present study indicates that tumor cells in the desmoplastic component strongly expressed TSP-1 in invasive ductal carcinoma of the breast and TSP-1 participates in invasion of these tumors. Our findings also suggest that TSP-1 promotes lymph node metastasis and TSP-1 potentially could be a predictive marker for metastasis.

Inactivation of RASSF1A tumor suppressor gene by aberrant promoter hypermethylation in human pituitary adenomas.

Aberrant promoter methylation and resultant silencing of several tumor suppressor genes play an important role in the pathogenesis of many tumor types. The human Ras association domain family 1A gene (RASSF1A), recently cloned from the lung tumor locus at 3p21.3, was shown to be frequently inactivated by hypermethylation of its promoter region in a number of malignancies. We have investigated the expression and epigenetic changes of this novel universal tumor suppressor gene in pituitary adenomas and correlated the data with clinicopathologic findings. Fresh frozen normal pituitary tissues and 52 primary pituitary adenomas including all major types were examined. Methylation-specific polymerase chain reaction (MSP), combined bisulfite restriction analysis (COBRA), bisulfite sequencing and semiquantitative reverse transcription-polymerase chain reaction were used to analyze DNA promoter methylation status and the mRNA expression of RASSF1A, respectively. High levels of RASSF1A transcript and no methylation of the RASSF1A promoter were found in normal pituitary tissues. RASSF1A promoter methylation was detected in 20 of 52 (38%) adenomas including all major types of pituitary adenomas. However, a lower frequency of methylation of the RASSF1A promoter was found in gonadotroph cell adenomas (15%) compared with growth hormone cell, prolactin cell, or adrenocorticotropic hormone cell adenomas (54, 46 and 50%, respectively). Methylation frequency was higher in the most aggressive adenomas (87% in grade IV tumors, P=0.0163). In addition, methylation of the RASSF1A promoter potentially correlated with higher labeling index of the proliferation marker Ki-67 (P=0.1475). Loss or significant reduction of RASSF1A messenger RNA transcripts was identified in 18 of 20 (90%) adenomas with hypermethylation of RASSF1A (P<0.0001). Our data suggest that promoter hypermethylation of RASSF1A and resultant alterations of RASSF1A expression may play a critical role in pituitary tumorigenesis and may be involved in tumor progression.