Adrenocortical carcinoma with inferior vena cava tumor thrombus found during surgery.

Introduction: The safety and efficacy of minimally invasive approaches for adrenocortical carcinoma with inferior vena cava tumor thrombus have not yet been established. We report a case of large adrenocortical carcinoma with inferior vena cava tumor thrombus found perioperatively which required conversion from a laparoscopic to an open procedure. Case presentation: A 71-year-old woman with right-side 10-cm diameter adrenocortical carcinoma was scheduled for laparoscopic adrenalectomy. The operation was converted to open surgery, however, because inferior vena cava tumor thrombus, which was not detected by preoperative imaging modalities, was found during surgery. Conclusion: In patients with large adrenocortical carcinoma, the possible presence of inferior vena cava thrombus should be considered when selecting surgical procedures.

Low-grade serous carcinoma detected from intraoperative peritoneal washings: Cytological findings and detection of KRAS mutation.

BACKGROUND: Low-grade serous carcinoma (LGSC) of the ovary, which is extremely rare tumor, has better prognosis than high-grade serous carcinoma (HGSC). Genetic backgrounds of those are different, so that LGSC usually shows KRAS or BRAF mutation, whereas HGSC does not show such mutations. Since treatment strategies of those are different, differential pathological diagnosis between LGSC and HGSC is very important. CASE: We report a case of LGSC that was diagnosed by both cytological findings and genetic analysis using small amount cells from cytological specimen. The 30-year-old Japanese woman with bilateral ovarian tumors underwent salpingo-oopherectomy. The peritoneal washing cytologic specimen and touched cytologic specimen from the tumor included non-complex clusters with psammoma bodies composed of tumor cells with mild to moderate atypia and without bizarre nuclei. The ovarian tumor was histologically diagnosed as LGSC. The genetic analysis that was done using exfoliated cells from peritoneal washings specimen by idensy™, detected KRAS mutation at codon 12/13. CONCLUSION: The genetic investigation using cytological specimen as well as characteristic cytological findings were useful to make differential diagnosis between LGSC and HGSC.

Intracranial Hemorrhage in a Patient with TAFRO Syndrome Treated with Cyclosporine A and Rituximab.

TAFRO syndrome, a rare subtype of idiopathic multicentric Castleman disease, manifests as thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly. Thrombotic microangiopathy, including renal dysfunction, is frequently associated with this syndrome. TAFRO syndrome can be life threatening and show rapid progression, and the diagnosis and management of this disorder remain challenging. A 48-year-old woman was diagnosed with TAFRO syndrome complicated by thrombotic microangiopathy based on the clinical and histopathological findings. After receiving high-dose steroids, her thrombocytopenia and anasarca did not improve. The patient subsequently received a combination of cyclosporine A and rituximab as second-line therapy, which resulted in a significant gradual improvement in the clinical symptoms. Meanwhile, her platelet count increased to more than 40 × 109/L; however, she developed intracranial hemorrhage. Following surgical evacuation, the patient recovered with an achievement of sustained remission. Based on these findings, attention should be paid to life-threatening bleeding associated with local thrombotic microangiopathy even when intensive treatment is administered for TAFRO syndrome.

[Erdheim-Chester disease diagnosed with right atrium tumors].

Erdheim-Chester disease (ECD) is a very rare form of the non-Langerhans histiocytic multisystem disorder. The cardiac involvement is often challenging and is associated with poor prognosis. Transthoracic echocardiography was used to detect right atrium tumors in a 62-year-old man with heart failure who was admitted to our hospital. The circumferential soft tissue sheathing of the aorta (coated aorta) and fat infiltration around the kidneys (hairy kidneys) was seen on a contrast-enhanced computed tomography strongly suspecting ECD imaging. The patient was diagnosed with ECD based on histopathology reports of the surgical resection tumor. The characteristic imaging findings of ECD may contribute to an early and accurate diagnosis.

Paneth-like cells in renal cell carcinomas and in cysts associated with acquired cystic kidney disease: Clinicopathologic analysis, comparative study and description of precursor lesions.

Paneth-like cells (PLCs) are different from Paneth cells (PCs) and contain Paneth-like granules, which have been reported in non-neoplastic conditions and in neoplasms of various organs. PLCs have been reported in clear cell renal cell carcinoma (CCRCC), but not in non-CCRCC, including acquired cystic disease-associated renal cell carcinoma (ACD-RCC). We analyzed clinicopathological features of 24 acquired cystic disease-associated renal cell carcinoma (ACD-RCC) with PLCs (ACD-RCCP+) and compared with those of 23 ACD-RCCs without PLCs (ACD-RCCP-). Approximately half of ACD-RCCs had PLCs and that almost all kidneys harboring ACD-RCC had cysts with PLCs. The fact that many ACD-RCCs and the cysts had PLCs is further evidence that the cyst with vacuoles and complex architecture might be a precursor lesion for ACD-RCC. The presence of PLCs may provide additional morphologic clue for distinguishing ACD-RCC from PRCC in challenging differential diagnostic workup in acquired cystic disease of the kidney setting.

A case report of synchronous bilateral tonsillar carcinoma associated with human papilloma virus.

The case of a 69-year-old man with bilateral synchronous tonsillar carcinoma is reported. The patient complained of nasal closure, strange voice, and discomfort in his pharynx when he was admitted to the Department of Otolaryngology Head and Neck Surgery at Wakayama Medical University, Wakayama, Japan, in March 2017. The palatine tonsils were enlarged and the surface was irregular. Left cervical lymphadenopathy was also evident. Histological examination from both tonsils was performed and bilateral tonsillar squamous cell carcinoma was diagnosed. PCR analysis showed the same HPV-DNA pattern from bilateral tonsils. Concurrent chemoradiotherapy was performed. Total 70 Gy of irradiation (2Gy/day×35 day) was applied to bilateral tonsillar tumours and upper neck. Follow up was conducted every three months and the patient was free of recurrence for three years. Patient's informed consent was taken to publish the case report.

Microtubule-organizing center-mediated structural atypia in low- and high-grade urothelial carcinoma.

Urothelial carcinoma (UC) comprises two subtypes, low grade (LG-UC) and high grade (HG-UC), with different pathological and clinical behavior. LG-UC and HG-UC are classified based on cellular and structural atypia of pathological findings. The mechanisms responsible for maintaining structural atypia, such as the disturbance of nuclear polarity, remain unclear. In this study, we studied microtubule-organizing center (MTOC)-mediated nuclear polarity in UC subtypes. We evaluated six cases with normal urothelium (NU), 10 LG-UC cases, and 10 HG-UC cases by double immunofluorescence staining of γ-tubulin as a marker of MTOC and E-cadherin as a marker of each cell border. The number and position of γ-tubulin dots of expression in more than 100 cells per case were assessed using the spatial relationship with the nucleus and surface-basal axis. We found one γ-tubulin dot in most normal and tumor cells, and more than two γ-tubulin dots in 4.6% of NU cells, 6.1% of LG-UC cells, and 9.8% of HG-UC cells. More than three γ-tubulin dots were found only in 1.2% of HG-UC cells. Surface side positioning of γ-tubulin was found in 77.4% of normal urothelial cells, 63.8% of LG-UC cells, and 39.2% of HG-UC cells, whereas aberrant lateral and basal side positioning of γ-tubulin was found in 22.6% of normal urothelial cells, 36.1% of LG-UC cells, and 60.8% of HG-UC cells. We concluded that numerical and positional aberrations of MTOC in UC cases were strongly correlated with both cellular and structural atypia as well as abnormal cell proliferation.

Balloon-Assisted Embolization of Wide-Neck Aneurysms Using a Mixture of n-Butyl Cyanoacrylate, Lipiodol, and Ethanol in Swine: A Comparison of Four n-Butyl Cyanoacrylate Concentrations.

PURPOSE: To determine the optimal ratio of n-butyl cyanoacrylate (NBCA)-Lipiodol-ethanol (NLE) mixture for balloon-assisted embolization of wide-neck aneurysms. MATERIALS AND METHODS: We created 32 wide-neck aneurysms on both the common carotid arteries and external iliac arteries in eight female swine. Eight aneurysms were randomly assigned to four groups. Under balloon occlusion, the aneurysms were packed using NLE at one of four ratios of NLE: 2:2:1 (NLE221; 40%NBCA); 3:6:1 (NLE361; 30%NBCA); 2:7:1 (NLE271; 20%NBCA); and 1:5:1 (NLE151; 14.3%NBCA). We performed angiography before and after embolization to assess the aneurysms, and we compared adhesion between NLE and the balloon and assessed NLE migration. Three days after embolization, the aneurysms were removed for histopathologic evaluation. RESULTS: Embolization was performed in 27 aneurysms. Adhesion between NLE and the balloon was not observed in any group. NLE migration was found in 0/7 aneurysms in the NLE221 group, 0/6 in the NLE361 group, 5/6 in the NLE271 group, and 7/8 in the NLE151 group. NLE migration was significantly lower in the NLE221 group than in the NLE271 and NLE151 groups (P = 0.0047 and 0.0014, respectively) and was significantly lower in the NLE361 group than in the NLE271 and NLE151 groups (P = 0.0152 and 0.0047, respectively). Media necrosis of the arterial wall close to the aneurysms was observed in all groups. CONCLUSION: NLE with an NBCA concentration of ≥ 30% is a safe and feasible embolic material for balloon-assisted embolization of wide-neck aneurysms in swine in the short term up to 3 days after embolization.

Measurement and visualization of cell membrane surface charge in fixed cultured cells related with cell morphology.

The diagnosis of patients with malignancies relies on the results of a clinical cytological examination. To enhance the diagnostic qualities of cytological examinations, it is important to have a detailed analysis of the cell's characteristics. There is, therefore, a need for developing a new auxiliary method for cytological diagnosis. In this study, we focused on studying the charge of the cell membrane surface of fixed cells, which is one of important cell's characteristics. Although fixed cells lose membrane potential which is observed in living cells owing to ion dynamics, we hypothesized that fixed cells still have a cell membrane surface charge due to cell membrane components and structure. We used 5 cell lines in this study (ARO, C32TG, RT4, TK, UM-UC-14). After fixation with CytoRich Red, we measured the cell membrane surface charge of fixed cells in solution using zeta potential measurements and fixed cells on glass slides, visualizing it using antibody-labeled beads and positively-charged beads. Furthermore, we measured the cell membrane surface charge of fixed cells under different conditions, such as different solution of fixative, ion concentration, pH, and pepsin treatments. The zeta potential measurements and visualization using the beads indicated that the cell membrane surface of fixed cells was negatively charged, and also that the charge varied among fixed cells. The charge state was affected by the different treatments. Moreover, the number of cell-bound beads was small in interphase, anaphase, and apoptotic cells. We concluded that the negative cell membrane surface charge was influenced by the three-dimensional structure of proteins as well as the different types of amino acids and lipids on the cell membrane. Thus, cell surface charge visualization can be applied as a new auxiliary method for clinical cytological diagnosis. This is the first systematic report of the cell membrane surface charge of fixed cells.

Brentuximab vedotin for refractory anaplastic lymphoma kinase-negative anaplastic large cell lymphoma in leukemic phase with RUNX3 overexpression.

Anaplastic lymphoma kinase (ALK)- negative anaplastic large cell lymphoma (ALCL) is an aggressive CD30-positive non- Hodgkin lymphoma. ALK-ALCL rarely manifests with extensive bone marrow and peripheral blood involvement (known as "leukemic phase"). A 54-year-old woman was diagnosed with ALK-ALCL in leukemic phase, characterized by an extremely poor prognosis. Lymphoma cells in this case showed chromosomal translocation 1p36.1- encoded RUNX3 and overexpression of its protein. She was refractory to CHOP and salvage chemotherapy. Fortunately, she achieved complete remission with three cycles of Brentuximab vedotin (BV) and underwent umbilical cord blood transplantation. However, she died due to treatment-related mortality on day 129. The autopsy findings showed no lymphoma cells. Treatment strategy for ALK-ALCL is controversial, but the efficacy of BV in CD30-positive peripheral T-cell lymphoma not only as salvage regimens, but also in first line, has been reported in recent years. BV may be an effective option for ALK-ALCL in leukemic phase.

False-positive staining of thyroglobulin distinguished from mixed medullary and follicular thyroid carcinoma by duplex in situ hybridization.

Medullary thyroid carcinoma (MTC) may mimic mixed medullary and follicular thyroid carcinoma (MMFTC). MTC originates from para-follicular cells, while MMFTC is an uncommon tumor characterized by coexistence of follicular and para-follicular cell-derived tumor populations. A 35-year-old woman was diagnosed with MTC but showed a hot nodule in thyroid scintigraphy. The tumor included diffusely-spread follicular lesions within it, which were immunostained with thyroglobulin and calcitonin. Immunofluorescence showed the presence of several tumor cells that were double-stained with thyroglobulin and calcitonin. To clarify whether or not the tumor was MMFTC, we used duplex in situ hybridization (ISH). Thyroglobulin and calcitonin-related polypeptide alpha mRNA were not expressed together in a single cell, so we suspected false-positive staining of tumor cells with thyroglobulin. To make comparisons with other follicular lesions in MTC, we searched our hospital database. Five cases within a ten-year period had been pathologically diagnosed as MTC. All had follicular lesions in the tumor, but unlike the other case, they were peripherally localized. Dual differentiation into follicular or para-follicular tumor cells was not indicated by either immunofluorescence or duplex ISH. Compared with the case suspected to be MMFTC, there was only mild invasion of tumor cells into the follicular epithelium. The extent of follicular lesions and invasiveness of tumor cells may be associated with pseudo-staining of thyroglobulin in MTC. Duplex ISH can distinguish MTC that are stained with thyroglobulin from MMFTC.

Comprehensive Clinicopathologic Analyses of Acquired Cystic Disease-associated Renal Cell Carcinoma With Focus on Adverse Prognostic Factors and Metastatic Lesions.

Acquired cystic disease of kidney-associated renal cell carcinoma (ACD-RCC) is a distinct subtype of renal cell carcinoma with unique morphologic and clinicopathologic features. Generally, ACD-RCC is regarded as an indolent tumor; however, prognostic and outcomes data have been conflicted by the limited and relatively low number of cases with patient follow-up or adverse events. In this study, we focused on the histology of metastatic lesions and identifying prognostic factors associated with metastatic progression. From 32 cases in the cohort, 9 patients had metastasis [ACD-RCC (M+)] and 23 patients were without metastasis [ACD-RCC (M-)]. The median age of patients was 52 years; right side, n=10; left side, n=18; bilateral, n=4; median tumor size=2.6 cm; median hemodialysis duration=17 y; and the median duration of follow-up was 50 mo. Immunohistochemistry showed ACD-RCC to be racemase positive and CK7 negative to focally positive within tumor cells, with consistent positivity for renal histogenesis-associated markers (PAX8 and RCC antigen); S100A1 was a less reliable marker at metastatic sites. All metastatic ACD-RCC except 2 cases involved lymph nodes (para-aortic, renal hilar, subclavicular). Overall, 6/9 (67%) had visceral metastasis to sites including lung (n=3), liver (n=3), bone (n=5), stomach (n=1), and brain (n=1). In total, 5/9 (56%) metastatic tumors had distinctive cystic growth pattern at the metastatic site; intriguingly metastatic tumors had intrametastatic oxalate crystal deposition, a pathognomonic feature associated with primary tumors. Four of nine (44%) patients with ACD-RCC (M+) had fatal outcomes due to metastatic disease. Clinically significant adverse prognostic features associated with metastasis [median follow-up 47 mo, ACD-RCC (M+) vs. ACD-RCC (M-), 50 mo] included: duration of hemodialysis (≥20 vs. <20 y, P=0.0085) and tumor necrosis (P=0.049). Because of sufficient overlap between these parameters, the study was not able to identify parameters that would be reliable in further management strategies, in clinical settings. Our data indicate that ACD-RCC is a tumor which has distinct metastatic potential with nodal and visceral tropism and proclivity for cystic morphology at metastatic sites; this is the first report of the presence of oxalate crystals in metastatic tumors. Our data suggest that ACD-RCC patients with prolonged hemodialysis and tumoral coagulative necrosis require additional surveillance in view of the association of these parameters with metastatic progression.

Head and Neck Paraganglioma Atypically Carrying a Succinate Dehydrogenase Subunit B Mutation (L157X).

A 53-year-old woman was admitted to a hospital for gradual left-ear hearing loss over 2 years. Head computed tomography revealed a 2-cm mass along the left jugular bulb and another at the right carotid bulb. The right tumor was resected; the pathological diagnosis was carotid body paraganglioma. Mutations of succinate dehydrogenase (SDH) were suspected, but SDHB staining remained in the tumor. Genetic testing identified a known SDHB mutation (L157X). The patient had head and neck paraganglioma with an SDHB mutation (L157X) more typical of an SDHD mutation. SDHB immunohistochemistry is useful for detecting SDHx mutations, but careful interpretation is needed.

A rare case of the recurrent surgery for cribriform-morular variant of papillary thyroid carcinoma.

INTRODUCTION: The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is an uncommon subtype of PTC, and it is associated with familial adenomatous polyposis (FAP). PRESENTATION OF CASE: We describe a 32-year-old female who presented recurrent CMV-PTC with FAP. Surgery performed after the recurrent disease resulted in left recurrent laryngeal nerve palsy due to formation of strong scar after initial operation. The histopathological examination revealed the recurrent CMV-PTC without thyroid capsular invasion in remnant thyroid tissue of berry ligament. In addition, the immunohistochemical analysis showed that ß-Catenin was diffusely positive in both cytoplasm and nucleus in CMV-PTC tissue. CONCLUSION: Total thyroidectomy in CMV-PTC with FAP should be performed at initial surgery due to high recurrence.

Adipophilin expression in cutaneous malignant melanoma is associated with high proliferation and poor clinical prognosis.

Adipophilin (ADP) is a primary protein component of lipid droplets (LDs). For more than half a century, certain types of cancer cells have been known to contain LDs in their cytoplasm. However, the pathological significance of ADP or LDs in cancer remains unclear. In the present study, we investigated the association between ADP and other pathological characteristics in cutaneous malignant melanomas to clarify the role of ADP in melanoma cells. We immunostained whole paraffin sections of primary cutaneous melanomas obtained from 90 cases for ADP, after which we analyzed the correlation between ADP immunohistochemistry (IHC) and patient survival data. We also studied the relationship between the ADP IHC score and in situ hybridization (ISH) score of ADP mRNA, and the Ki67-labeling index (Ki67-LI) by using tissue microarrays consisting of 74 primary cutaneous malignant melanomas, 19 metastasizing melanomas, and 29 melanocytic nevi. Finally, we analyzed the relationship between ADP expression and cell proliferation in cutaneous melanoma cell lines. We found that high ADP expression was associated with poor metastasis-free survival, disease-specific survival, and overall survival rates of patients with cutaneous melanomas (P < 0.05). By linear regression analysis, ADP IHC was correlated with increasing ADP mRNA ISH H-scores and Ki67-LI scores in melanocytic lesions (P < 0.01). ADP IHC and ADP ISH H-scores and Ki67-LI scores were greater in pT3-4 melanomas than in pT1-2 melanomas. In cell-based assays, cells with increased ADP expression showed higher proliferation rates compared with those of low-ADP cells. Thus, ADP expression in malignant melanoma was significantly associated with high cell proliferation and poor clinical prognosis. Our results thus indicate a significant association between ADP and melanoma progression, and we propose that ADP may be a novel marker of aggressive cutaneous melanoma with a lipogenic phenotype.

Tumor Budding Is an Objective High-risk Factor Associated With Metastasis and Poor Clinical Prognosis in Cutaneous Squamous Cell Carcinoma Sized <4 cm.

Although most cases of early cutaneous squamous cell carcinoma (CSCC) are indolent, a small subset metastasize and can be fatal. However, high-risk features of CSCC are controversial, and it is difficult to predict the biological behavior. In this study, we have tested the prognostic significance of tumor budding in CSCCs <4 cm in diameter. Hematoxylin and eosin-stained sections of surgically resected CSCCs (24 metastasizing and 24 nonmetastasizing cases) <4 cm in size were reviewed retrospectively. Tumor bud, defined as an isolated cancer cell or a cluster comprising<5 cells, was counted at a hot spot (1.23 mm), and graded between 1 and 3; grade 1: 0 to 4 buds; grade 2: 5 to 9 buds; and grade 3: ≥10 buds. Cases with grades 2 or 3 were regarded as positive for tumor budding. We found that tumor budding was positive in 83.3% of metastasizing CSCC, and 37.5% of nonmetastasizing CSCC (P<0.01). Moreover, CSCCs with grade 3 tumor budding showed worse disease-specific survival (P<0.01). Regarding interobserver reproducibility, the median κ value for tumor budding was significantly higher than that for histologic differentiation (P<0.01). In conclusion, tumor budding may be a valuable histologic marker for risk stratification of early CSCC in routine practice. Patients with tumor budding positive CSCC may benefit from evaluation and close follow-up for regional node metastasis.

High-Risk Human Papillomavirus E6/E7 mRNA Is Rarely Detected in Nonanogenital Cutaneous Squamous Cell Carcinoma: An RNA In Situ Hybridization-Based Tissue Microarray Study.

High-risk human papillomavirus (HR-HPV) is known to play an oncogenic role in squamous cell carcinoma (SCC) at certain anatomical sites, namely the uterine cervix, oropharynx, and anogenital skin. However, the association between HR-HPV and nonanogenital cutaneous SCC (CSCC) remains controversial. In this study, we addressed this controversy by performing HR-HPV E6/E7 mRNA in situ hybridization (ISH) on 243 CSCC samples. A cocktail of E6/E7 mRNA ISH probes, recognizing 18 HR-HPV genotypes, was applied to a tissue microarray of paraffin-embedded sections of 154 invasive and 89 in situ CSCC specimens. The anatomical sites of CSCC included the head and neck (n = 100), extremities (n = 100), trunk (n = 25), and anogenitalia (n = 18). We also investigated the correlation between the p16 expression and HR-HPV status by immunohistochemistry. The results of HR-HPV E6/E7 mRNA ISH showed that 5.8% (14/243) of all CSCC samples were positive for HR-HPV, including 66.7% (12/18) of the anogenital and only 0.9% (2/225) of the nonanogenital CSCC samples (P < 0.01). For the detection of diffuse p16 expression by immunohistochemistry, the sensitivity was 100% (14/14 HR-HPV-positive CSCC samples), and the specificity was 72.1% (165/229 HR-HPV-negative specimens). Thus, HR-HPV E6/E7 mRNA was rarely detected in nonanogenital CSCC, making it unlikely that the virus contributes to the pathogenesis of this malignancy. In addition, p16 immunoreactivity has a limited value as a surrogate marker for transcriptionally active HR-HPV in nonanogenital CSCC.

Predominant Improvement of Alpha Cell Function after Steroid Therapy in a Patient with Autoimmune Pancreatitis: Case Report.

INTRODUCTION: Autoimmune pancreatitis (AIP) is a subset of inflammatory pancreatic disease, responsive to corticosteroid therapy. It is prone to being affected by diabetes mellitus, but the effectiveness of steroid therapy on pancreatic endocrine function is still controversial. We present a case of AIP, focusing on pancreatic endocrine function after steroid therapy. CASE REPORT: The patient was referred to our hospital with exacerbation of diabetic control and pancreatic swelling. By admission, the insulin secretory capacity was severely impaired. The patient was diagnosed with AIP and treated with prednisolone, resulting in marked improvement of the pancreatic swelling. Glycemic control worsened transiently after initiation of steroid therapy, but insulin requirements decreased along with tapering prednisolone dosage. Pancreatic cytology showed that the acinar structure had been destroyed, and the islets had disappeared. Insulin and glucagon immunostaining revealed slightly scattered alpha and beta cells within the fibrotic stroma. The patient notably showed improved pancreatic alpha cell function predominantly after steroid therapy, despite partial improvement of beta cell function. CONCLUSION: An imbalance between alpha and beta cell function may contribute to insufficient diabetic control in some patients with AIP. The pancreatic endocrine function test in combination with pancreatic cytology could be helpful when considering the treatment strategy for diabetic control in patients with AIP.

HER2 is frequently overexpressed in hepatoid adenocarcinoma and gastric carcinoma with enteroblastic differentiation: a comparison of 35 cases to 334 gastric carcinomas of other histological types.

AIMS: α-Fetoprotein (AFP)-producing gastric carcinoma (AFPGC) is one of the most aggressive GC subtypes. Frequent expression of human epidermal growth factor receptor 2 (HER2) has previously been reported in hepatoid adenocarcinoma (HAC), a major histological subtype of AFPGC originating from common-type GC (CGC). However, HER2 expression levels in other AFPGC histological subtypes are unknown. In this study, we analysed HER2 expression in GCs with primitive phenotypes in addition to HAC. METHODS: HER2 expression was evaluated in representative complete sections from 16 HACs, 19 GCs with enteroblastic differentiation (GCEDs) and 334 GCs of other histological types as controls. The Ruschoff/Hofmann method was used to score HER2 immunohistochemistry. Samples with a HER2 score of 2+ were further assessed using fluorescence in situ hybridisation. Oncofetal protein (OFP) expression in HAC and GCED was tested via immunohistochemical staining for AFP, glypican 3 and Sal-like protein 4. RESULTS: Thirty of 35 HAC/GCED cases comprised more than two histological patterns. The HER2 positivity rates of each histological component in the HACs/GCEDs were 25.0% for HAC (n=16), 34.6% for GCED (n=26) and 48.1% for CGC (n=27), which were higher than those of the control group (13.8%). Additionally, the majority of CGC components in HACs/GCEDs were positive for OFP (88.9%). CONCLUSIONS: HER2 is frequently overexpressed not only in HAC but also in GCED and CGC components of HACs/GCEDs, which suggests an association between HER2 and OFP expression. Moreover, our findings suggest that HER2-positive CGC has a higher risk of progression to HAC/GCED than HER2-negative GC.