Ladinin-1 in actin arcs of oral squamous cell carcinoma is involved in cell migration and epithelial phenotype.

Histopathologically, oral squamous cell carcinoma (OSCC) consists of well-defined interfaces with adjacent non-cancerous epithelium. Previously, we found that SCC tissues expressed higher levels of specific proteins at this interface. Ladinin-1 (LAD1) is one of the specific molecules that has increased expressions in cancer fronts; however, its function in OSCC is unknown. Therefore, this study aimed to elucidate the function of LAD1 in human OSCC cells. LAD1 was localized on the actin arc at the distal periphery of cell clusters in the OSCC cell lines HSC-2, HSC-3, and HSC-4. When LAD1 was knocked down, cellular migration was repressed in wound scratch assays but was reversed in three-dimensional collagen gel invasion assays. Characteristic LAD1 localization along actin arcs forming the leading edge of migrating cells was diminished with loss of filopodia formation and ruffling in knockdown cells, in which the expression levels of cell motility-related genes-p21-activated kinase 1 (PAK1) and caveolin-1 (CAV1)-were upregulated and downregulated, respectively. LAD1 expression was also associated with the downregulation of vimentin and increased histological differentiation of OSCC. These results suggest that LAD1 is involved in actin dynamics during filopodia and lamellipodia formation, and in maintaining the epithelial phenotype of OSCC cells.

Cell-cell interaction determines cell fate of mesoderm-derived cell in tongue development through Hh signaling.

Dysfunction of primary cilia leads to genetic disorder, ciliopathies, which shows various malformations in many vital organs such as brain. Multiple tongue deformities including cleft, hamartoma, and ankyloglossia are also seen in ciliopathies, which yield difficulties in fundamental functions such as mastication and vocalization. Here, we found these tongue anomalies in mice with mutation of ciliary protein. Abnormal cranial neural crest-derived cells (CNCC) failed to evoke Hh signal for differentiation of mesoderm-derived cells into myoblasts, which resulted in abnormal differentiation of mesoderm-derived cells into adipocytes. The ectopic adipose subsequently arrested tongue swelling formation. Ankyloglossia was caused by aberrant cell migration due to lack of non-canonical Wnt signaling. In addition to ciliopathies, these tongue anomalies are often observed as non-familial condition in human. We found that these tongue deformities could be reproduced in wild-type mice by simple mechanical manipulations to disturb cellular processes which were disrupted in mutant mice. Our results provide hints for possible future treatment in ciliopathies.

Oral Focal Mucinosis of the Tongue: Case Report and Review of the Literature.

Oral focal mucinosis (OFM) is an oral mucosal lesion characterized by focal mucosal accumulation that rarely occurs on the tongue. This report describes a rare case of OFM on the right side of the tongue in a 71-year-old female patient. The clinical features of OFM have not been well defined, making it difficult to differentiate it from other lesions based solely on clinical manifestations; therefore, histopathological examinations are necessary. Although OFM on the tongue is rare and has a good prognosis with resection, it should be considered as differential for painless mass lesions in the oral cavity.

Right-sided versus left-sided colorectal cancer in elderly patients: a sub-analysis of a large multicenter case-control study in Japan.

PURPOSE: This study investigated the impact of sidedness of colorectal cancer (CRC) in elderly patients on the prognosis. METHODS: In a sub-analysis of a multicenter case-control study of CRC patients who underwent surgery at ≥ 80 years old conducted in Japan between 2003 and 2007, both short- and long-term outcomes were compared between right-sided colon cancers (RCCs) and left-sided colorectal cancers (LCCs). RCCs were defined as those located from the cecum to the transverse colon. RESULTS: Among the 1680 patients who underwent curative surgery, 812 and 868 had RCCs and LCCs, respectively. RCCs were more frequent than LCCs in those who were female, had renal comorbidities, and had a history of abdominal surgery. Regarding tumor characteristics, RCCs were larger, invaded more deeply, and were diagnosed as either mucinous or signet ring-cell carcinoma more frequently than LCCs. Regarding the prognosis, patients with RCCs had a significantly longer cancer-specific survival (CS-S) and cancer-specific relapse-free survival (CS-RFS) than those with LCCs. Furthermore, sidedness was determined to be an independent prognostic factor for CS-S and CS-RFS. CONCLUSION: RCCs, which accounted for half of the cases in patients ≥ 80 years old, showed better long-term outcomes than LCCs.

Evaluation of the advantage of surgeons certified by the endoscopic surgical skill qualification system participating in laparoscopic low anterior rectal resection.

Background: A technical qualification system was developed in 2004 by the Japan Society for Endoscopic Surgery. An analysis of the EnSSURE study on 3188 stage II-III rectal cancer patients, which was performed by including the participation of qualified surgeons as assistants and advisers without restricting their participation as operators, revealed that the participation of technically qualified surgeons in surgery improved the technical and oncological safety of laparoscopic rectal resection. Aim: This secondary retrospective analysis of the EnSSURE study examined the advantage of qualified surgeons participating in laparoscopic low anterior resection (LAR). Methods: The outcomes of low anterior resection were compared between groups with and without the participation of surgeons qualified by the Endoscopic Surgical Skill Qualification System (Q and non-Q groups, respectively). We used propensity score matching to generate paired cohorts at a one-to-one ratio. The postoperative complication rate, short-term results (hemorrhage volume, operative time, number of dissected lymph nodes, open conversion rate, intraoperative complication rate, and R0 resection rate), and long-term results (disease-free survival rate, local recurrence rate, and overall survival rate) were evaluated. Results: The frequencies of postoperative complications, anastomotic bleeding, and intraperitoneal abscess were significantly lower, the operative time was significantly shorter, the postoperative hospital stay was significantly shorter, and the number of dissected lymph nodes was higher in the Q group. No significant differences were observed in disease-free survival, local recurrence, or overall survival rate rates between the groups. Conclusion: The participation of qualified surgeons in LAR is technically advantageous.

Long-term survival and functional outcomes of laparoscopic surgery for clinical stage I ultra-low rectal cancers located within 5 cm of the anal verge: A prospective phase II trial (Ultimate trial).

OBJECTIVE: To clarify the long-term oncological outcomes and postoperative anal, urinary, and sexual functions after laparoscopic surgery for clinical stage I very low rectal carcinoma located near the anal canal. SUMMARY BACKGROUND DATA: Laparoscopic surgery is widely applied for rectal cancer; however, concerns remain, with some studies showing poorer outcomes compared to open surgery. METHODS: This single-arm, phase II trial included patients registered preoperatively from 47 institutions in Japan. The planned sample size was 300. The primary endpoint was the 3-year local recurrence rate. Anal, urinary, and sexual functions were evaluated using a prospective questionnaire. RESULTS: Three-hundred patients were registered between January 2014 and March 2017. Anus-preserving surgery was performed in 278 (93%), including 172 who underwent intersphincteric resection (58%) and 106 (36%) who underwent low anterior resection. The 3-year cumulative local recurrence rate was 6.3%. At 3 years postoperatively, 87% of patients used their own anus, and the median incontinence score improved from 12 at 3 months to 8 at 3 years. Only 5% of patients had severe incontinence (incontinence score of 16 points). Postoperative urinary function evaluation showed that International Prostate Symptom Score and Overactive Bladder Symptom Score decreased 1 week after surgery, but recovered to preoperative level 1 month after surgery. International Consultation on Incontinence Questionnaire-Sort Form remained almost stable after surgery. Sexual function evaluation using the International Index of Erectile Function-5 and International Index of Erectile Function-15 revealed that the patients had deteriorated 3 months after surgery but had recovered only slightly by 6 months. CONCLUSIONS: Laparoscopic surgery achieves feasible long-term oncological outcomes and a high rate of anus preservation with moderate anal function, and an acceptable incontinence score. While urinary function recovered rapidly, sexual function showed poor recovery.

Wnt/ß-catenin-C-kit axis may play a role in adenoid cystic carcinoma prognostication.

Adenoid cystic carcinoma (ACC) is one of the most common malignant salivary gland tumors. ACC is composed of myoepithelial and epithelial neoplastic cells which grow slowly and have a tendency for neural invasion. The long term prognosis is still relatively poor. Although several gene abnormalities, such as fusions involving MYB or MYBL1 oncogenes and the transcription factor gene NFIB, and overexpression of KIT have been reported in ACC, their precise functions in the pathogenesis of ACC remain unclear. We recently demonstrated that the elevated expression of Semaphorin 3A (SEMA3A), specifically expressed in myoepithelial neoplastic cells, might function as a novel oncogene-related molecule to enhance cell proliferation through activated AKT signaling in 9/10 (90%) ACC cases. In the current study, the patient with ACC whose tumor was negative for SEMA3A in the previous study, revisited our hospital with late metastasis of ACC to the cervical lymph node eight years after surgical resection of the primary tumor. We characterized this recurrent ACC, and compared it with the primary ACC using immunohistochemical methods. In the recurrent ACC, the duct lining epithelial cells, not myoepithelial neoplastic cells, showed an elevated Ki-67 index and increased cell membrane expression of C-kit, along with the expression of phosphorylated ERK. Late metastasis ACC specimens were not positive for ß-catenin and lymphocyte enhancer binding factor 1 (LEF1), which were detected in the nuclei of perineural infiltrating cells in primary ACC cells. In addition, experiments with the GSK-3 inhibitor revealed that ß-catenin pathway suppressed not only KIT expression but also proliferation of ACC cells. Moreover, stem cell factor (SCF; also known as KIT ligand, KITL) induced ERK activation in ACC cells. These results suggest that inactivation of Wnt/ß-catenin signaling may promote C-kit-ERK signaling and cell proliferation of in metastatic ACC.

High-level phenol bioproduction by engineered Pichia pastoris in glycerol fed-batch fermentation using an efficient pertraction system.

This study aimed to establish a high-level phenol bioproduction system from glycerol through metabolic engineering of the yeast Pichia pastoris (Komagataella phaffii). Introducing tyrosine phenol-lyase to P. pastoris led to a production of 59 mg/L of phenol in flask culture. By employing a strain of P. pastoris that overproduces tyrosine-a precursor to phenol-we achieved a phenol production of 1052 mg/L in glycerol fed-batch fermentation. However, phenol concentrations exceeding 1000 mg/L inhibited P. pastoris growth. A phenol pertraction system utilizing a hollow fiber membrane contactor and tributyrin as the organic solvent was developed to reduce phenol concentration in the culture medium. Integrating this system with glycerol fed-batch fermentation resulted in a 214 % increase in phenol titer (3304 mg/L) compared to glycerol fed-batch fermentation alone. These approaches offer a significant framework for the microbial production of chemicals and materials that are highly toxic to microorganisms.

Comparing the Diagnostic Accuracy of Ultrasonography, CT, MRI, and PET/CT in Cervical Lymph Node Metastasis of Oral Squamous Cell Carcinoma.

(1) Background: In oral cancer staging, ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) with positron emission tomography/computed tomography (PET/CT) are routinely used in clinical practice. The present study is a retrospective examination of the diagnostic accuracy of cervical lymph node metastasis using US, CT, MRI, and PET/CT, with histopathological diagnosis as a reference, to compare the different diagnostic imaging modalities. (2) Methods: The participants included 16 patients with oral squamous cell carcinoma who underwent US-, CT-, MRI-, and PET/CT-based preoperative diagnostic imaging and simultaneous primary lesion resection and neck dissection, including 82 level regions and 424 lymph nodes. We compared the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of each imaging modality based on the imaging results and the pathology results of metastasis. (3) Results: Of the four diagnostic imaging modalities, PET/CT exhibited the highest sensitivity but the lowest specificity and accuracy. US, CT, and MRI had high specificities. Comparing each level region and lymph node showed that differences were observed in PET/CT. (4) Conclusions: PET/CT to diagnose lymph node metastasis requires a comprehensive evaluation because it produces more false positives than other diagnostic imaging modalities. Using US, CT, and MRI, which have excellent spatial resolution, improves diagnostic accuracy at the lymph node level.

Hypoxia-Induced Biosynthesis of the Extracellular Matrix Molecules, Perlecan and Fibronectin, Promotes the Growth of Pleomorphic Adenoma Cells In Vitro Models.

Salivary pleomorphic adenoma is histopathologically characterized by its colorful stroma with myxoid, chondroid, and hyaline appearances, due to enhanced biosynthesis of extracellular matrix (ECM) molecules and poor vascularity. Thus, pleomorphic adenoma cells embedded in the stroma typically survive under hypoxic conditions. We determined the expression kinetics of ECM molecules, such as perlecan and fibronectin (FN), under hypoxia in SM-AP1 cells which are duct epithelial differentiated cells, and in SM-AP4 cells, which are myoepithelial differentiated cells, cloned from pleomorphic adenoma of the parotid gland. We investigated hypoxia-inducible factor-1α (HIF-1α)-inducing pathways through a variety of ECM molecules in association with their cellular proliferation and migration. We observed that hypoxic conditions with elevated HIF-1α protein levels induced increased expression of perlecan and FN in SM-AP cells than in controls. Moreover, perlecan and FN knockdown reduced the proliferation of SM-AP1 and SM-AP4 cells under hypoxia. Further, SM-AP1 cell migration was enhanced by both perlecan and FN knockdown, whereas SM-AP4 cell migration was increased by perlecan knockdown and inhibited by fibronectin knockdown. The results indicated that pleomorphic adenoma cells can survive under hypoxic conditions by promoting cell proliferation via enhanced synthesis of ECM molecules. Overall, ECM molecules may be a new anti-tumor target under hypoxic conditions.

A randomized phase II study comparing preoperative mFOLFOX6 versus FOLFOXIRI for locally advanced colon cancer: JCOG2006.

The prognosis of locally advanced colon cancer (LACC) with surgical resection followed only by adjuvant chemotherapy is poor. Preoperative chemotherapy for LACC patients with risk factors such as cT4bN+ or cT3-4aN2-3 has attracted attention. Here, the authors describe the rationale and design of JCOG2006, a randomized phase II study comparing preoperative chemotherapy with mFOLFOX6 versus FOLFOXIRI for LACC. Their efficacy and safety are evaluated and a determination of which is the more promising treatment will be conducted in a subsequent phase III trial. A total of 86 patients will be accrued from 44 institutions over 2 years. The primary end point is the proportion of patients with a Tumor Regression Score of 0-2, and secondary end points include overall survival, response rate and adverse events. Clinical Trial Registration: jRCTs031210365 (https://jrct.niph.go.jp/).

Solitary choroidal metastasis of distal cholangiocarcinoma: A case report.

Metastatic choroidal carcinoma is rare and generally has a poor prognosis. The present case report describes a case of choroidal metastasis from distal cholangiocarcinoma, which was successfully managed using stereotactic radiotherapy (SRT). A 67-year-old Japanese man underwent pancreaticoduodenectomy for distal cholangiocarcinoma. The pathological stage was T2N0M0 stage IIA, according to the Union for International Cancer Control 8th edition. After surgery, the patient received adjuvant chemotherapy with oral TS-1® for 1 month. A total of 2 months after surgery, the patient was readmitted to hospital due to decreased visual acuity. Fundoscopy revealed a macular hole in the right eye that accounted for the decreased visual acuity. Additionally, Goldmann three-mirror contact lens examination revealed a 4-mm choroidal mass with a yellowish color situated at a considerable distance from the optic nerve. Magnetic resonance imaging revealed an enhanced choroidal mass. Based on the findings of ophthalmologic examinations and the patient's history of cholangiocarcinoma, they were diagnosed with choroidal metastasis from distal cholangiocarcinoma. SRT was administered at a total dose of 40 Gy divided into 8 Gy fractions. A total of 1 year after SRT, the patient achieved complete remission without decreased visual acuity. The patient remains alive and in good health without recurrence, 4 years after the diagnosis of choroidal metastasis. To the best of our knowledge, this is the second reported case of intraocular metastasis from cholangiocarcinoma. In conclusion, SRT may provide an opportunity to control metastatic choroidal carcinoma without decreasing visual acuity.

Significance of timing of therapeutic line on effectiveness of nivolumab for metastatic renal cell carcinoma.

Objectives: This study aimed to clarify the significance of therapeutic timing on the effectiveness of nivolumab for treating metastatic renal cell carcinoma. Marterials and methods: Fifty-eight patients with metastatic renal cell carcinoma treated with nivolumab monotherapy were retrospectively studied. Patients who were treated with nivolumab as second-line therapy were included in the second-line group, while the others were included in the later-line group. The clinicopathological characteristics, effects of nivolumab, and prognoses of these groups were compared. Results: Twenty and thirty-eight patients were included in the second-line and later-line groups, respectively. There were no significant differences in the distribution of International Metastatic Renal Cell Carcinoma Database Consotium risk and other clinicopathological characteristics between the 2 groups. The proportion of patients whose objective best response was progressive disease in the second-line group was significantly lower than that in the later-line group (15% vs. 50%, p = 0.0090). The 50% progression-free survival with nivolumab in the second-line group was significantly better than that in the later-line group (not reached and 5 months, p = 0.0018). Multivariate analysis showed that the second-line setting was an independent predictive factor for better progression-free survival (p = 0.0028, hazard ratio = 0.108). The 50% overall survival after starting nivolumab in the second-line and later-line groups was not reached and 27.8 months, respectively (p = 0.2652). Conclusions: The therapeutic efficacy of nivolumab as second-line therapy is expected to be better than that of later therapy.

A lesson from polybutylene succinate plastisphere to the discovery of novel plastic degrading enzyme genes in marine vibrios.

Polybutylene succinate (PBS) is an eco-friendly green plastic. However, PBS was shown as being non-biodegradable in marine environments, and up until now, only a limited number of PBS-degrading marine microbes have been discovered. We first set up in vitro PBS- and PBSA (polybutylene succinate adipate)-plastispheres to characterize novel PBS-degrading marine microbes. Microbial growth and oxygen consumption were observed in both PBS- and PBSA-plastispheres enriched with natural seawater collected from Usujiri, Hokkaido, Japan, and Vibrionaceae and Pseudoalteromonadaceae were significantly enriched on these films. Further gene identification indicated that vibrios belonging to the Gazogenes clade possess genes related to a PBS degrading enzyme (PBSase). The PBS degradation assay for six Gazogenes clade vibrios identified Vibrio ruber, Vibrio rhizosphaerae, and Vibrio spartinae as being capable of degrading PBS. We further identified the gene responsible for PBSase from the type strain of V. ruber, and the purified recombinant vibrio PBSase was found to have low-temperature adaptation and was active under high NaCl concentrations. We also provided docking models between the vibrio PBSase and PBS and PBSA units to show how vibrio PBSase interacts with each substrate compared to the Acidovorax PBSase. These results could contribute to a more sustainable society through further utilization of PBS in marine environments and plastic recycling.

Clinical significance of metastatic tumor deposit foci in rectal cancer in the lateral pelvic lymph node area.

BACKGROUND: Although previous studies have demonstrated that tumor deposits (TDs) are associated with worse prognosis in colon cancer, their clinical significance in rectal cancer has not been fully elucidated, especially in the lateral pelvic lymph node (LPLN) area. This study aimed to clarify the clinical significance of TDs, focusing on the number of metastatic foci, including lymph node metastases (LNMs) and TDs, in the LPLN area. METHODS: This retrospective study involved 226 consecutive patients with cStage II/III low rectal cancer who underwent LPLN dissection. Metastatic foci, including LNM and TD, in the LPLN area were defined as lateral pelvic metastases (LP-M) and were evaluated according to LP-M status: presence (absence vs. presence), histopathological classification (LNM vs. TD), and number (one to three vs. four or more). We evaluated the relapse-free survival of each model and compared them using the Akaike information criterion (AIC) and Harrell's concordance index (c-index). RESULTS: Forty-nine of 226 patients (22%) had LP-M, and 15 patients (7%) had TDs. The median number of LP-M per patient was one (range, 1-9). The best risk stratification power was observed for number (AIC, 758; c-index, 0.668) compared with presence (AIC, 759; c-index, 0.665) and histopathological classification (AIC, 761; c-index, 0.664). The number of LP-M was an independent prognostic factor for both relapse-free and overall survival, and was significantly associated with cumulative local recurrence. CONCLUSION: The number of metastatic foci, including LNMs and TDs, in the LPLN area is useful for risk stratification of patients with low rectal cancer.

Masticatory muscle tendon-aponeurosis hyperplasia that was initially misdiagnosed for polymyositis: a case report and review of the literature.

BACKGROUND: Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a relatively newly identified clinical condition that manifests as trismus with a square-shaped mandible. Herein, we report a case of MMATH that was initially misdiagnosed for polymyositis due to trismus and simultaneous lower limb pain, with literature review. CASE PRESENTATION: A 30-year-old woman had a history of lower limb pain after exertion for 2 years. Initial physical examination had been performed at the Department of General Medicine in our hospital. There was also redness in the hands and fingers. Although polymyositis was suspected, it was denied. The patient visited our department for right maxillary wisdom tooth extraction. Clinical examination revealed that the patient had a square-shaped mandible. The maximal mouth opening was 22 mm. There was no temporomandibular joint pain at the time of opening. Furthermore, there was awareness of clenching while working. Panoramic radiography revealed developed square mandibular angles with flattened condyles. Computed tomography showed enlarged masseter muscles with high-density areas around the anterior and lateral fascia. Magnetic resonance imaging also showed thickened tendons and aponeuroses on the anterior surface and inside bilateral masseter muscles. Finally, the patient was diagnosed with MMTAH. Bilateral aponeurectomy of the masseter muscles with coronoidectomy and masseter muscle myotomy was performed under general anesthesia. The maximum opening during surgery was 48 mm. Mouth opening training was started on day 3 after surgery. Histopathological examination of the surgical specimen showed that the muscle fibers were enlarged to 60 µm. Immunohistochemistry testing for calcineurin, which was associated with muscle hypertrophy due to overload in some case reports, showed positive results. Twelve months after surgery, the mouth self-opening and forced opening were over 35 mm and 44 mm, respectively. CONCLUSIONS: Herein, we report a case of MMATH. Lower limb pain due to prolonged standing at work and overload due to clenching were considered risk factors for symptoms onset of MMATH.

Alkane production from fatty alcohols by the combined reactions catalyzed by an alcohol dehydrogenase and an aldehyde-deformylating oxygenase.

PsADH, an alcohol dehydrogenase originating in Pantoea sp. was characterized and found to convert a broad variety of fatty alcohols into their corresponding aldehydes, the substrates of alkane biosynthesis. By coupling PsADH with NpAD, a cyanobacterial aldehyde-deformylating oxygenase, and by optimizing the conditions of the enzyme-catalyzed reactions, we achieved a 52% conversion of 1-tetradecanol to tridecane. We further applied this system to generate alkanes ranging from C5-17. These alkanes can be used as biofuels, suggesting that introducing a suitable alcohol dehydrogenase is an effective strategy to utilize fatty alcohols for alkane production.

Cholesterol Is a Regulator of CAV1 Localization and Cell Migration in Oral Squamous Cell Carcinoma.

Cholesterol plays an important role in cancer progression, as it is utilized in membrane biogenesis and cell signaling. Cholesterol-lowering drugs have exhibited tumor-suppressive effects in oral squamous cell carcinoma (OSCC), suggesting that cholesterol is also essential in OSCC pathogenesis. However, the direct effects of cholesterol on OSCC cells remain unclear. Here, we investigated the role of cholesterol in OSCC with respect to caveolin-1 (CAV1), a cholesterol-binding protein involved in intracellular cholesterol transport. Cholesterol levels in OSCC cell lines were depleted using methyl-ß-cyclodextrin and increased using the methyl-ß-cyclodextrin-cholesterol complex. Functional analysis was performed using timelapse imaging, and CAV1 expression in cholesterol-manipulated cells was investigated using immunofluorescence and immunoblotting assays. CAV1 immunohistochemistry was performed on surgical OSCC samples. We observed that cholesterol addition induced polarized cell morphology, along with CAV1 localization at the trailing edge, and promoted cell migration. Moreover, CAV1 was upregulated in the lipid rafts and formed aggregates in the plasma membrane in cholesterol-added cells. High membranous CAV1 expression in tissue specimens was associated with OSCC recurrence. Therefore, cholesterol promotes the migration of OSCC cells by regulating cell polarity and CAV1 localization to the lipid raft. Furthermore, membranous CAV1 expression is a potential prognostic marker for OSCC patients.

Liquid-based cytology for differentiating two cases of pemphigus vulgaris from oral squamous cell carcinoma.

Pemphigus vulgaris (PV) is a rare autoimmune disease characterized by blisters on the skin and mucous membrane. Since it often appears in the oral mucosa first, it may be diagnosed by oral mucosal cytology. Although the cytologic finding is characterized by acantholytic cells, that is, Tzanck cells, it is important to distinguish PV from neoplastic lesions of the oral mucosal epithelium, including differentiation from atypical parabasal/basal cells, which appear in squamous cell carcinoma (SCC). In this study, we examined the cellular findings in two cases of PV and a case of well-differentiated SCC with loss of epithelial cell cohesion. The samples were prepared using liquid-based cytology, which showed small round-shaped and deeply stained atypical, orangeophilic keratinocytes not only in SCC but also in PV, which made differentiation between the two difficult. However, Tzanck cells found in PV differ from the deep atypical parabasal/basal cells of SCC, suggesting that the cell outline is indistinct and small protrusions and brush-like structures are observed. This feature of Tzanck cells may be useful in cytological judgment.