Stratified Squamous Cells Research Articles

Comparative Morphological and Histochemical Study of Esophagus, in Eurasian Collared Dove (Streptoplia decaocto) and Buzzard (Beuteo beuteo vulpinus)

The study carried out on 28 esophagus specimens of healthy, 14 Eurasian Collared Dove (Streptoplia decaocto) and 14 Buzzard (Beuteo beuteo vulpinus). The aimed, to study the esophagus's morphological also histological. The lumen of esophagus in dove appear narrower and shorter in length than Buzzard as well as the crop as well-developed sac , while the crop in buzzard as longitudinal narrow spindle dilation ,and the present research work was done on the histology and histochemistry of the esophagus in dove and buzzard and found that the esophagus was composed of three segment cervical, crop and thoracic ,histologically, the mucosa of cervical, thoracic part was lined by non-keratinized layer of stratified squamous cells. As well as The esophageal glands were absent in cervical part and crop in dove, whereas in the thoracic part these glands were present and their duct open toward the lumen of the esophagus. The mucosal folds well developed in the cervical portion. Histochemically, the epithelium gland of esophagus showed PAS positive reaction that indicated presence of neutral mucopolysaccharides, the esophageal glands showed strong moderate reaction by (PAS)in cervical and thoracic esophagus as well as in thoracic part in dove. Conclusion the results showed that esophagus was significantly different Morphological and histological between two birds.

Keratin 6A Is Expressed at the Invasive Front and Enhances the Progression of Colorectal Cancer

Keratins (KRTs) are intermediate filament proteins in epithelial cells, and they are important for cytoskeletal organization. KRT6A, classified as a type II KRT, is normally expressed in stratified squamous epithelium and squamous cell carcinomas. Little is known about the expression and role of KRT6A in adenocarcinomas. We investigated the clinicopathologic and molecular biological significance of KRT6A in colorectal adenocarcinoma. Immunostaining of colorectal adenocarcinoma cases treated at our institution demonstrated that KRT6A showed significantly stronger expression at the invasive front than that at the tumor center (P < .0001). The high KRT6A–expression cases (n = 47) tended to have a high budding grade associated with significantly worse prognoses. A multivariate analysis revealed that the KRT6A expression status was an independent prognostic factor for overall survival (P = .0004), disease-specific survival (P = .0097), and progression-free survival (P = .0033). The correlation between KRT6A and patient prognoses was also validated in an external cohort from a published data set. To determine the function of KRT6A in vitro, KRT6A was overexpressed in 3 colon cancer cell lines: DLD-1, SW620, and HCT 116. KRT6A overexpression increased migration and invasion in DLD-1 but did not in SW620 and HCT116. In 3-dimensional sphere-forming culture, KRT6A expression enhanced the irregular protrusion around the spheroid in DLD-1. Our findings in this study indicated that KRT6A expression is a valuable prognostic marker of colorectal cancer and KRT6A may be involved the molecular mechanism in the progression of invasive areas of colorectal cancer.

Histological study of seventeen organs from dugong (Dugong dugon).

Dugongs are marine mammals with a crescent-shaped tail fluke and a concave trailing margin that belong to the family Dugongidae., They are distributed widely in the warm coastal waters of the Indo-Pacific region. Importantly, the population of dugongs has decreased over the past decades as they have been classified as rare marine mammals. Previous studies have investigated the habitat and genetic diversity of dugongs. However, a comprehensive histological investigation of their tissue has not yet been conducted. This study provides unique insight into the organs of dugongs and compares them with other mammal species. Tissue sections were stained with Harris's hematoxylin and eosin Y. The histological structure of 17 organ tissues obtained from eight systems was included in this study. Tissue sections were obtained from the urinary system (kidney), muscular system (striated skeletal muscle and smooth muscle), cardiovascular system (cardiac muscle (ventricle), coronary artery, and coronary vein), respiratory system (trachea and lung), gastrointestinal system (esophagus, stomach, small intestine, liver, and pancreas), reproductive system (testis), lymphatic system (spleen and thymus), and endocrine system (pancreas). While most structures were similar to those of other mammal species, there were some differences in the tissue sections of dugongs when compared with other mammalian species and manatees. These include the kidneys of dugongs, which were non-lobular and had a smooth, elongated exterior resulting in a long medullary crest, whereas the dugong pyloric epithelium did not have overlying stratified squamous cells and was noticably different from the Florida manatee. Histological information obtained from various organs of the dugong can serve as an essential foundation of basal data for future microanatomical studies. This information can also be used as high-value data in the diagnosis and pathogenesis of sick dugongs or those with an unknown cause of death.

Two Head and Neck Carcinomas With Squamous and Mucinous Components and Human Papillomavirus Associations: Maxillary Mucoepidermoid Carcinoma ex Sinonasal Schneiderian Papilloma and Tonsillar Invasive Stratified Mucin Producing Carcinoma (ISMC).

Carcinomas of the head-and-neck region with squamous and glandular/mucinous features constitute a heterogeneous group, with a significant minority of tumors showing an human papillomavirus (HPV) association. The differential diagnosis is usually between mucoepidermoid carcinoma (MEC) and adenosquamous carcinoma. We present here two tumors that exemplify both the challenges of diagnostic classification, as well as the complex relationship to HPV: (a) a low risk HPV positive/p16 negative carcinoma that is most consistent with a relatively typical intermediate grade mucoepidermoid type carcinoma with complete MEC phenotype (three cell types), originating from intranasal sinonasal papillomas with exophytic and inverted patterns, and invading surrounding maxillary compartments, and (b) a p16 and keratin 7 (KRT7) positive carcinoma of the right tonsil, characterized by stratified squamous and mucinous cell (mucocyte) features. Whereas the first tumor represents a typical MEC ex-Schneiderian papilloma, the second is morphologically most consistent with the, novel for this anatomic location, diagnosis of "invasive stratified mucin producing carcinoma" (ISMC), pointing to an analogy to similar, high-risk HPV-driven malignancies recently described in the gynecologic (GYN) and genitourinary (GU) areas. Both tumors, despite their mucoepidermoid-like features had no connection to salivary glands and lacked the MAML2 translocation typical of salivary gland MEC, pointing to a mucosal/non-salivary gland origin. Using these two carcinomas as examples, we attempt to address questions related to: (a) the histological distinction between MEC, adenosquamous carcinoma, and ISMC, (b) similarities and differences between these histological entities in mucosal sites versus morphologically similar salivary gland tumors, and (c) the role of HPV in these tumors.

Transmembrane Mucin Response in Conjunctival Epithelial Cells Exposed to Wall Shear Stresses

Human conjunctival epithelium cells (HCEC) line the inner surface of the eyelid and cover the sclera and are continuously subjected to wall shear stresses (WSS). The effects of external forces on the conjunctival epithelium are not fully known. The conjunctival epithelium contains stratified squamous cells that synthesize the membrane-spanning mucins MUC1 and MUC16, which play important roles in protecting the ocular surface. Alterations in both gel-forming and membrane-tethered mucins occur in drying ocular surface diseases. The aim of this study was to explore the mechanobiological characteristics of transmembrane mucin secretion and cellular alterations of primary HCEC exposed to airflow-induced WSS perturbations. We exposed the HCEC to a steady WSS of 0.5 dyne/cm2 for durations of 15 and 30 min. Cytoskeletal alterations and MUC1 secretions were studied using immunohistochemically fluorescent staining with specific antibodies. We investigated for the first time an in vitro model of membrane-tethered mucin secretion by HCEC in response to WSS. The exposure of HCEC to WSS increased the polymerization of F-actin, altered the cytoskeletal shape and reduced the secretion of membrane-tethered MUC1.

Concise Review: Bioengineering of Limbal Stem Cell Niche.

The corneal epithelium is composed of nonkeratinized stratified squamous cells and has a significant turnover rate. Limbal integrity is vital to maintain the clarity and avascularity of the cornea as well as regeneration of the corneal epithelium. Limbal epithelial stem cells (LESCs) are located in the basal epithelial layer of the limbus and preserve this homeostasis. Proper functioning of LESCs is dependent on a specific microenvironment, known as the limbal stem cell niche (LSCN). This structure is made up of various cells, an extracellular matrix (ECM), and signaling molecules. Different etiologies may damage the LSCN, leading to limbal stem cell deficiency (LSCD), which is characterized by conjunctivalization of the cornea. In this review, we first summarize the basics of the LSCN and then focus on current and emerging bioengineering strategies for LSCN restoration to combat LSCD.

Local and Metastatic Relapses in a Young Woman with Papillary Squamous Cell Carcinoma of the Uterine Cervix.

Papillary squamous cell carcinoma (PSCC) is a rare histological type of cervical carcinoma whose biological behavior has not been fully established. A 33-year-old woman with an exophytic cervical mass underwent radical hysterectomy and bilateral pelvic lymph node dissection. Histological examination of the tumor revealed numerous papillary fronds lined by atypical stratified squamous cells, resembling high-grade squamous intraepithelial lesions or urothelium. She was diagnosed with stage IB1 PSCC. Three months postoperatively, a 5.7 cm vaginal stump mass was detected. She received chemoradiotherapy, which helped her achieve a complete response. However, nine months postoperatively, she developed pelvic lymph node metastases. We present a rare case of recurrent cervical PSCC in a young woman. PSCC of the uterine cervix can recur rapidly within just a few months and become aggressive, as in the present case.

Inverted Ductal Papilloma of the Salivary Gland

This is a case consult of slides stated to be from an excision of a buccal mucosa mass in a 58-year-old-man. The specimen was described as a 3 cm diameter roughly oval tan-gray tissue with a 2 x 1.5 cm mucosal ellipse on the surface that has a central ulcerated punctum. Cut section showed an underlying 1.7 cm diameter roughly oval well-circumscribed mass with a granular tan surface. Histological sections show a papillary lesion with an orifice on the mucosal surface and with epithelial nests invaginating into the underlying lamina propria in a non-infiltrative pattern. (Figure 1) The lesion is composed of papillary epithelial fronds with cleft-like spaces between the fronds. (Figure 2) The papillary fronds are lined by non-keratinizing basaloid stratified squamous cells with a superficial layer of columnar glandular cells along with mucous goblet cells interspersed among the squamous cells. (Figure 3) All the cellular components are devoid of cytologic atypia and mitoses. Based on these microscopic features we signed the case out as inverted ductal papilloma (IDP).&#x0D; &#x0D; Ductal papillomas are uncommon benign epithelial tumors with a papillary configuration that originate from the excretory ductal system of salivary gland acini.1-3 The World Health Organization recognizes two sub-types depending on the growth pattern: an intraductal papilloma (IP) and an IDP.1 An IDP usually presents as an asymptomatic submucosal nodule, measuring about 1.5 centimeters in diameter, and most commonly involving the buccal mucosa, followed by the lips, palate, and floor of the mouth.2,3 Histological sections typically show an unencapsulated though well-circumscribed epithelial proliferation with a papillary configuration on the luminal surface, and a nodular, endophytic or invaginating (“inverted”) configuration at its interface with the underlying lamina propria.2 Both the papillary and the invaginating areas are composed of basaloid, non-keratinizing stratified squamous epithelium that are often covered with a cuboidal or columnar ductal cell layer.2 Scattered among these are mucous goblet cells which can form microcysts.1,2 There is an overall morphological similarity to the sinonasal inverted papilloma.3 A relationship to trauma has been proposed.1,4 Association with Human Papilloma Virus (HPV) has also been reported.1 Others, however, have not been able to demonstrate this association.4&#x0D; &#x0D; Differential diagnoses primarily include IP - which is differentiated from IDP architecturally by being a unicystic intraluminal papillary proliferation within a dilated excretory duct 2 – and sialadenoma papilliferum – which is predominantly polypoid and pedunculated with a verrucoid surface rather than a submucosal nodule, and an over-all morphologic similarity to the cutaneous tumor syringocystadenoma papilliferum.1,4 An important differential diagnosis that has to be ruled out is mucoepidermoid carcinoma (MECA) because of the presence of both squamous and mucin-secreting cells. MECA is distinguished by poor circumscription, and an infiltrative solid-cystic growth pattern.2,4&#x0D; &#x0D; IDP is benign and non-recurrent. Unlike the nasal tumor, there has been no report of malignant transformation.2,3 Complete surgical excision is considered curative.1,2 Reporting these cases is encouraged to further our knowledge of the entity and elucidate a potential association with HPV.

The development and stem cells of the esophagus.

The esophagus is derived from the anterior portion of the foregut endoderm, which also gives rise to the respiratory system. As it develops, the esophageal lining is transformed from a simple columnar epithelium into a stratified squamous cell layer, accompanied by the replacement of unspecified mesenchyme with layers of muscle cells. Studies in animal models have provided significant insights into the roles of various signaling pathways in esophageal development. More recent studies using human pluripotent stem cells (hPSCs) further demonstrate that some of these signaling pathways are conserved in human esophageal development. In addition, a combination of mouse genetics and hPSC differentiation approaches have uncovered new players that control esophageal morphogenesis. In this Review, we summarize these new findings and discuss how the esophagus is established and matures throughout different stages, including its initial specification, respiratory-esophageal separation, epithelial morphogenesis and maintenance. We also discuss esophageal muscular development and enteric nervous system innervation, which are essential for esophageal structure and function.

Branchial Cleft Anomalies in Children

INTRODUCTION: Objective: A retrospective study was planned to evaluate the clinical and radiological findings of childhood branchial anomalies together with the subclasses of the anomaly and to discuss the surgical results. Method: The medical records of the patients managed for branchial cleft anomaly between 2014 and 2019 were examined. Demographic features, clinical and radiological findings, surgical managements and outcomes were recorded. Results: Eighteen cases were included in the study. Median age of the cases was 5 years (1-14). Male/female ratio was 9/9. The complaints were discharge from the BC (n=13, 72%) and painless neck mass (n=3, 17%). The BC was at right side in 8 (44%), left side in 9 (%50) and bilateral in 1 case (6%). Physical examination revealed the presence of a fistula, and its orifice in 14 cases and cystic lesion was palpable in 4 cases. Ultrasound was performed in 9 cases (50%) and cyst could be detected in 3 of them. All cases were operated and step-ladder incision was used in 8 cases. The fistula tract was ended near to pharynx in 2, near to pretonsillar fossa in 10, submandibular region in 5, and external auditory tract in 1 case. Histopathological examination revealed inflammation in 2 cases and cartilage in 1 case. Stratified ciliary columnar and stratified squamous cell epithelium was detected in samples. Conclusion: Physical examination is the most important diagnostic method. The management is surgery and excision of whole lesion is important in preventing recurrences. Although using methylene blue is a guiding technique in surgical excision of tracts, the effect of its use on surgical outcome and recurrence rates is still debatable.

S3431 An Odd Place for Acne: Ectopic Esophageal Sebaceous Glands

INTRODUCTION: Sebaceous glands are typically found on the skin, providing lubrication to the skin and hair follicles. These glands are generally clustered on the face and scalp with fewer being found on the remaining skin surface. Esophageal sebaceous glands are extremely rare. As of 2017, less than 25 case reports had been published on this entity. Although rare and therefore not fully understood, esophageal sebaceous glands have not been linked to any attributable symptoms or risk or cancer. The following is a case of a patient evaluated for chronic cough who was ultimately found to have sebaceous glands in his esophagus. CASE DESCRIPTION/METHODS: A 63-year-old man was seen in gastroenterology clinic for evaluation of chronic cough and globus sensation. An esophagogastroduodenoscopy (EGD) displayed yellow, plaque-like material extending from proximal to distal esophagus (images A and B). These lesions could not be removed with lavage and were subsequently biopsied. The biopsy demonstrated a collection of round cohesive cells with cleared out cytoplasm and small centrally located nuclei arranged in an acinar configuration, consistent with ectopic sebaceous glands (image C). These glands are located within the lamina propria underlying a normal appearing stratified squamous cell epithelium. The patient also had esophageal pH testing showing a normal DeMeester score. Patient was treated with nasal fluticasone with improvement in his presenting symptoms. Therefore, symptoms were attributed to post-nasal drip, rather than the ectopic sebaceous glands. DISCUSSION: Ectopic esophageal sebaceous glands are a rare, benign finding. There is no known malignant potential to these lesions and no known attributable symptoms. Although rare and benign, endoscopists should have a familiarity with the appearance of ectopic esophageal sebaceous glands in order to distinguish them from other, non-benign lesions (such as squamous cell carcinoma) and potentially avoid unnecessary biopsies or other invasive testing.Figure 1.: Esophagus with sebaceous glands.Figure 2.: Esophagus with sebaceous glands.Figure 3.: Pathology slide of sebaceous glands in the esophagus.

Povidone iodine treatment is deleterious to human ocular surface conjunctival cells in culture

ObjectiveTo determine the effect of povidone iodine (PI), an antiseptic commonly used prior to ocular surgery, on viability of mixed populations of conjunctival stratified squamous and goblet cells, purified conjunctival...

Establishment of Immortalized Laryngeal Epithelial Cells Transfected with Bmi1

Primary laryngeal epithelial cells are essential to exploring the mechanisms of laryngeal and voice disorders; however, they are difficult to study and apply because of their limited life span. The purpose of this study was to develop a stable and reliable in vitro model for the comprehensive study of the pathogenesis of laryngeal and voice diseases. The pLVTHM-Bmi1 plasmid was constructed and used to immortalize primary laryngeal epithelial cells by lentiviral infection. The expressions of Bmi1, human telomerase reverse transcriptase (hTERT), p53, and pRB pathway proteins were detected by western blotting. Functional characteristics of the immortalized cell lines were verified by cell senescence β-galactosidase staining, 5-ethynyl-2′-deoxyuridine cell proliferation test, and flow cytometry. We successfully introduced Bmi into human subglottic (hSG) cells and human ventricle (hV) cells. Both the human immortalized subglottic Bmi1 (hSG-Bmi1) cell line and the human immortalized ventricle Bmi1 (hV-Bmi1) cell line maintained normal epithelial morphology and divided successfully after more than 20 culture passages. As Bmi1 was overexpressed in these cells, the expression of human telomerase reverse transcriptase (hTERT) and phosphorylated Rb increased while p16 and p21 decreased. Following Bmi1-mediated immortalization, cell senescence decreased significantly, and cell proliferation was accelerated. Tumor formation was not observed for hSG, hV, or hSG-Bmi1, and hV-Bmi1 cells in nude mice. hSG-Bmi1 cells dominated by stratified squamous epithelium and hV-Bmi1 cells dominated by columnar cells were established. The new cell lines lay a foundation for the study of the pathogenic mechanisms of laryngeal and voice diseases.

20 - GATA4 Inhibits Expression of P63 and its Downstream Targets in Stratified Squamous Cells

20 - GATA4 Inhibits Expression of P63 and its Downstream Targets in Stratified Squamous Cells

Human Conjunctival Epithelial Sheets Grown on Poly(Lactic-Co-Glycolic) Acid Membranes and Cocultured With Human Tenon's Fibroblasts for Corneal Repair.

We determine the feasibility of human conjunctival epithelial cells (hCjECs) on poly(lactic-co-glycolic) acid (PLGA) membranes for corneal epithelium regeneration. hCjECs on PLGA or polyester (PET) membranes with or without coculture of human Tenon's fibroblasts (hTFs) were compared in vitro, and to determine whether epithelial sheets grown on PLGA membranes can repair injured rabbit corneal epithelium by transplantation for 2 weeks in vivo. Primary hCjECs were cultured on PLGA or the original PET membrane-based transwell inserts with or without coculture of hTFs on the floor of the culture plate. Cell behaviors, such as proliferation and differentiation, were compared. For in vivo assessment, the corneas of rabbits were burned, and PLGA-based epithelial sheets then were transplanted for 2 weeks before histologic staining was conducted and analyzed to determine the effectiveness of the repair. Primary human epithelial cells on the PLGA membrane showed an increased proliferation when cocultured with fibroblasts, which was confirmed by CCK-8 analysis, and upregulation of Ki67, with the expression of the epithelial marker CK19. The stratified squamous cell marker MUC1 and conjunctival cell marker MUC5AC also were expressed in the epithelial sheet. The epithelial defect in the burned corneas was decreased in the PLGA-based epithelial sheet treatment group (6.1% ± 1.6% of the area) compared to that in the no-treatment group (30.5% ± 6.3%) 2 weeks postoperatively. We developed a coculture system using a human feeder cell layer and PLGA membrane-based transwell inserts to create human conjunctival epithelial sheets. This system represents a promising strategy to regenerate corneal epithelium by transplantation.

A dermoid cyst of the caecum

We present a case of a 39-year-old female who was found to have an adnexal mass during routine obstetric review. On ultrasound there was a 9 cm cyst superior to the right ovary, which intraoperatively was localised to the caecum. On excision, a uniloculated cyst was seen deep to the muscularis propria of the caecum, adjacent to the appendix. The cyst contained soft creamy material admixed with hair. Microscopically, the cyst had a mature stratified squamous cell lining with scattered underlying pilosebaceous elements. In the absence of ovarian and lymphoid tissue, and without mesodermal or endodermal cellular components, a diagnosis of a dermoid cyst was made.

Cellular events and behaviors after grafting of stratified squamous epithelial cell sheet onto a hydrated collagen gel.

Autologous stratified squamous epithelial cell sheets have been successfully used to treat epithelial defects in tissues such as the cornea and the esophagus. However, the regenerative cellular events occurring in the grafted epithelial cells are unclear in the early stages of wound healing. In this study, we created an in vitro grafting model using cultured normal human epidermal keratinocyte (NHEK) sheets and a type I collagen gel to investigate the cellular processes that occur within the grafted cell sheet. Cultured NHEK cells successfully became a stratified squamous cell sheet resembling epithelial tissue, retained expression of cellular integrins and adhesion proteins, and adhered successfully to a type I collagen gel. After culture on the collagen gel, expression of E‐cadherin, and β‐catenin decreased in the cells of the basal layer of the grafted cell sheet, resembling events characteristic of a partial epithelial–mesenchymal transition (EMT). These basal cells also induced migration of the cell sheet. Those phenomena are consistent with the essential events that occur in the wound‐healing process observed previously in cell studies. Therefore, the epithelial cell sheet grafted onto a type I collagen gel is a suitable model in vitro to study cellular events and behaviors. Furthermore, we also addressed the therapeutic mechanisms by which the epithelial cell sheet promotes wound healing.

Artificial Polymeric Scaffolds as Extracellular Matrix Substitutes for Autologous Conjunctival Goblet Cell Expansion.

PurposeWe fabricated and investigated polymeric scaffolds that can substitute for the conjunctival extracellular matrix to provide a substrate for autologous expansion of human conjunctival goblet cells in culture.MethodsWe fabricated two hydrogels and two silk films: (1) recombinant human collagen (RHC) hydrogel, (2) recombinant human collagen 2-methacryloylxyethyl phosphorylcholine (RHC-MPC) hydrogel, (3) arginine-glycine-aspartic acid (RGD) modified silk, and (4) poly-D-lysine (PDL) coated silk, and four electrospun scaffolds: (1) collagen, (2) poly(acrylic acid) (PAA), (3) poly(caprolactone) (PCL), and (4) poly(vinyl alcohol) (PVA). Coverslips and polyethylene terephthalate (PET) were used for comparison. Human conjunctival explants were cultured on scaffolds for 9 to 15 days. Cell viability, outgrowth area, and the percentage of cells expressing markers for stratified squamous epithelial cells (cytokeratin 4) and goblet cells (cytokeratin 7) were determined.ResultsMost of cells grown on all scaffolds were viable except for PCL in which only 3.6 ± 2.2% of the cells were viable. No cells attached to PVA scaffold. The outgrowth was greatest on PDL-silk and PET. Outgrowth was smallest on PCL. All cells were CK7-positive on RHC-MPC while 84.7 ± 6.9% of cells expressed CK7 on PDL-silk. For PCL, 87.10 ± 3.17% of cells were CK7-positive compared to PET where 67.10 ± 12.08% of cells were CK7-positive cells.ConclusionsBiopolymer substrates in the form of hydrogels and silk films provided for better adherence, proliferation, and differentiation than the electrospun scaffolds and could be used for conjunctival goblet cell expansion for eventual transplantation once undifferentiated and stratified squamous cells are included. Useful polymer scaffold design characteristics have emerged from this study.

Epulis fibrosa identified in a 6-year-old Japanese girl

Epulis is a relatively common benign polypoid lesion that generally appears in the gingiva of individuals aged between 20 and 50 years. A 6-year-old Japanese girl came to our hospital for consultation regarding swelling of the marginal gingiva in the region between the maxillary left deciduous lateral incisor and canine. An intraoral examination revealed that the surface of the swollen mass was nonulcerated and smooth, and its color was similar to that of the surrounding gingival tissue. X-ray findings showed no calcified body or tooth germ malposition. The lesion was removed surgically under local anesthesia and histopathological findings showed it to be composed of fibrous connective tissue and blood vessels with minimal inflammatory cells, and covered by stratified squamous epithelium cells under the mucosa, which led to a diagnosis of epulis fibrosa. Patient prognosis has been good to date with no symptoms indicating recurrence.

A Case of Multiple Canaliform Median Raphe Cysts Showing a Mixed Type Lining of Epithelium: A Case Report and Review of the Literature.

Dear Editor: A 7-month-old boy presented with linearly arranged, multiple pinhead-sized to rice-sized whitish cysts along the median raphe from the perineum to the penile shaft (Fig. 1), which were present from birth and progressively increased in size and number. The lesions spread along the perineal raphe and had a cordlike appearance. The infant showed no signs of pain, tenderness, pruritus, or other symptoms. He had no history of medical disease or congenital anomaly, and the rest of the skin was normal. A skin biopsy was performed at the upper cystic portion of the lesion (Fig. 1), and the biopsy specimen showed the cysts located in the dermis with variable lining. Some parts were lined by stratified squamous epithelium with well-formed granular layer and keratin flakes. Other parts consisted of cuboidal urothelium-like epithelium with mucinous cells (Fig. 2). Thus, considering the site and the histologic features, a diagnosis of mixed-type median raphe cysts was made. Fig. 1 Linearly arranged, multiple, whitish cysts along the perineal raphe. The arrow indicates the canalicular appearance of the cysts. The arrowhead indicates the biopsy site. Fig. 2 (A) The biopsy revealed cysts located in the dermis that showed variable lining (H&E, ×100). (B) Focal part of the cyst wall lined by stratified squamous epithelium with well-formed granular layer and keratin flakes (H&E, ×400). ... Median raphe cysts are rare, benign congenital lesions that can develop anywhere along the midline of the ventral side of the male genital area. They can form from the urethral meatus to the anus and the perineum along the perineal raphe1. Histologically, they are classified into four types. The urethral type, the most common, consists of an urothelium-like epithelium, with a layer of columnar cells overlaid with several stratified layers of uniform small cells. The epidermoid type consists of stratified squamous cell epithelium. The glandular type consists of a well-formed intraepithelial glandular structure in the lining of the urethral epithelium. The mixed type, the second most common and the type of this case, consists of more than one type of epithelium, including the urethral epithelium with squamous metaplasia, urethral epithelium with mucinous cells, or a combination of these three1. Histomorphological features of the median raphe cyst are considered to be related to its embryonic origin and pathogenesis2. The pathogenesis is unclear, but several hypotheses have been proposed. First, the 'tissue trapping' theory states that median raphe cysts are caused by either a defective fusion of the urethral folds or an anomalous outgrowth of the epithelium during the development of the urethra2. Second, median raphe cysts may result from the anomalous developmental rest of the periurethral glands of Littre. This hypothesis may help explain glandular type median raphe cysts and the involvement of mucinous cells in some cases3. A third hypothesis suggests that blockage of the paraurethral ducts may underlie the development of median raphe cysts4. The canaliform median raphe cysts demonstrated in the present case are an uncommon presentation of this rare condition, and reports of these cysts are rare. Most patients present with a single isolated from or a few cysts. The patient described here presented with multiple, continuous cysts. This unique morphology makes diagnosis confusing due to its rarity and particular clinical features. Thus, histologic confirmation is often required5. Complete local excision is recommended for the symptomatic lesions to prevent possible complications. Furthermore, whether associated congenital anomalies are present should also be assessed.