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Cytokeratins are termed intermediate filaments as their diameter (7-11 nm) is intermediate between the larger microtubules (25 nm) and smaller microfilaments (4-6 nm). - They can be classified into two main types: type I (basic cytokeratins, K 1-8) and type II (acidic cytokeratins, K 9-20). - Cytokeratins always occur in pairs, of combination of type I with type II. In the absence of its pair, they are unstable and are Susceptible to degradation by proteases K1, K2, K10-12 : Specific to epidermal-type differentiation, are immunohistochemically expressed with high intensity in orthokeratinized areas and with less intensity in parakeratinized areas K6, K16 : Highly proliferative epithelium but absent in junctional epithelium which has high turnover rate K5, K14 : Stratification specific cytokeratins K19 : Only in parakeratinized epithelium (not in orthokeratinized) -Also seen in Junctional epithelium K4 and K13 : Sulcular Epithelium. It also expresses K19, and it normally does not contain Merkel cells

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Coronal (Frontal) Plane: Divides body into front and back sections - Sagittal plane: Divide body into left and right sections - Axial (Horizontal or transverse) plane: Divides body into upper and lower segments

Acquired Melanocytic Nevus (Common Mole, Nevo-cellular nevus) - Nevus cells typically lack the dendritic processes that melanocytes possess - BRAF gene mutation is responsible - Size is usually less than 6 mm & Most common intra-oral site is Hard Palate Histologically: zones of differentiation often are seen among the lesional cells. - Superficial nevus cells tend to be organized into small, round aggregates (thèques) and usually appear ovoid or epithelioid, with abundant cytoplasm and frequent intracellular melanin. - Deeper nevus cells may have less cytoplasm, are seldom pigmented, and appear much like lymphocytes. - Deepest nevus cells appear elongated and spindle-shaped, much like Schwann cells or fibroblasts. - Hence Nevus cells are classified as types A (epithelioid), B (lymphocyte-like), and C (spindle-shaped). Junctional Nevus(within epithelium) - Appears as sharply demarcated brown or black macule - Thèques are at the junction of the epithelium and connective tissue, especially at rete ridges - Highest malignant potential - These appear like falling -Abtropfung effect / falling off/ dropping off effect. Compound Nevus (within epithelium & Connective tissue) - Nevus cells proliferate to produce a slightly elevated, soft papule with a smooth surface - As the nevus cells proliferate, they begin to drop off into the underlying dermis or lamina propria. And present at epithelium junction area and connective tissue Intradermal / Intra-mucosal (within connective tissue only) - The degree of pigmentation becomes less; most lesions appear brown or tan. - As time passes, the nevus gradually loses its pigmentation, the surface may become papillomatous, and hairs may be seen growing from the center - Later nevus cells are found only within the connective tissue. - In the skin, this stage is called an intradermal nevus; the intraoral counterpart is called an intra- mucosal nevus (Most common type) Congenital Melanocytic nevus - Classified according to size: small (<1.5 cm in diameter), medium (1.5 cm to 20 cm in diameter), or large (>=20 cm in diameter). - Common is hypertrichosis within the lesion, which may become more prominent with age (giant hairy nevus) - A very large congenital nevus may give the appearance that the patient is wearing an article of clothing and, thus, may be termed a bathing trunk nevus or garment nevus. - Histologically: Unlike acquired melanocytic nevus, the congenital nevus extends into deeper levels of the dermis, with "infiltration" of nevus cells between collagen bundles and neurovascular bundles in the reticular dermis and surround normal adnexal skin structures Halo Nevus (Sutton Nevus) - Nevus with a hypopigmented border, resulting from nevus cell and melanocyte destruction by the immune system Spitz Nevus (Juvenile Melanoma) - Spitz nevi harbor HRAS mutations, whereas melanocytic nevi and melanomas tend to exhibit BRAF mutation - Lesional cells are either spindle-shaped or plump (epithelioid) and the two types often are intermixed - Solitary or coalescent eosinophilic globules (Kamino bodies) may be seen in epidermis or at junction of epidermis and dermis Blue Nevus - Proliferation of dermal melanocytes, usually deep within the connective tissue - Two major types are recognized: 1) Common blue nevus(2nd most common intraoral nevus) and 2) Cellular blue nevus - The blue color is due to the Tyndall effect (relates to the interaction of light with particles in a colloidal suspension) - Blue nevi typically exhibit mutations in the GNAQ gene - Oral lesions are almost always found on palate. - Appears as a macular or dome-shaped, blue or blue-black lesion smaller than 1 cm in diameter - Histologically: Collection of elongated, slender melanocytes with dendritic extensions and numerous melanin granules. Cells are located deep in lamina propria and usually align themselves parallel to the surface epithelium.

The material used for making the impression of the oral cavity of an infant with CLCP is a medium body silicone impression material (addition silicones) - The wash of light body need not be used, as the registration of the minute details is not necessary - Alginate material is generally not recommended due to the possibility of tearing of small chunks of material from impression leading to occlusion of nasal passages or branches of the respiratory tract

Loss of the eye can be the result of congenital defects, tumors or trauma (leading cause). Surgical approaches for removal of orbital contents according to their involvement and prosthetic requirement - Enucleation : Is the removal of the globe from the orbit, involving the separation of all of the connections between the globe and the patient - Evisceration : Involves the removal of the contents of the eye, while maintaining an intact scleral shell attached to the extraocular muscles. - Exenteration : Involves removal of the globe along with all the soft tissues of the orbit - After enucleation, as time goes on, the orbital contents tend to contract toward the orbital apex. This contracture leads to a deformity of the superior sulcus and extrusion of orbital implant and prosthesis - Conformer is a clear acrylic shell fitted after an enucleation if the final artificial eye is not available at the time of surgery to hold the shape of the socket and allow the eyelids to blink over the shell without rubbing the suture line. - Ocular implants restored orbital volume and were commonly used by the end of the 19 th century. Implant Selection: Implants replace the volume lost by the enucleated eye. Enucleation without implant placement is unusual and yields a poor cosmetic result. The implant promotes the motility of the ocular prosthesis and maintains cosmetic symmetry with the contralateral eye. Simple-Buried - The conjunctival lining is uninterrupted. - There is smooth apposition between the implant and the ocular prosthesis - Some refer to implantation of a sphere without muscle atachment as simple buried Buried Integrated - There is no interruption of conjunctival lining. - The anterior surface of implant is irregular to improve translation of implant movement to prosthesis movement. - These include Allen. Iowa, and Universal implants - Buried integrated implants are anchored by sutures to the reclus muscles. Exposed Integrated - Interrupted conjunctival lining allows direct coupling of tile implant (hydroxyapatite implant with peg) to the prosthesis. - Exposed-integrated implants are designed to improve prosthesis motility - Exposed-integrated (pegged) implants are more expensive and intrusive, requiring wrapping materials, radiographic analysis, and pegging procedures Exposed Integrated - They do not have a surface where rectus muscles can be anchored, nor they allow fibrovascular tissue to grow in them (this is why we call them non-integrated) - They include implants made of glass, rubber, iron, acrylic material, silicone, gold, silver, or polymethylmethacrylate. - Their only function is to replace the volume loss and to improve the cosmetic result. - If the surgeon wants to increase the motility of the implant and, consequently, of the prosthesis, the rectus muscles should be repositioned and sutured to the anterior pole of the implant in order to move the artificial eye when the implant moves. - Unfortunately, the movements achieved with this method are of smaller range than those achieved when the implant is pegged Non-porous implants - Nonporous alloplastic implants can be comprised of varied inert materials e.g. PMMA (Poly methyl methacrylate) and silicone - These materials are made into solid, spherical implants that are well tolerated, have a low extrusion risk and are a good choice for implants that will not be integrated, or pegged - Especially for patients who had infections in which porous implants are no longer an option Porous implants - Also known as biocompatible or bio-integrated materials are now more commonly used as the initial implant material - E.g. porous polyethylene, hydroxyapatite and aluminium oxide being the most common. - Due to the porous nature of these materials, fibrovascular ingrowth occurs, allowing for improved implant stability as well as decreasing rejection risk - Porous polyethylene is a smoother, softer material to which the extra ocular muscles can be directly attached during enucleation. - In contrast, hydroxyapatite creates a rough, abrasive surface. To protect the overlying tissue and to serve as a scaffold for reattachment of the extraocular muscles, the hydroxyapatite implant is wrapped in materials ranging from donor sclera or autologous tissue to synthetic Vicryl or polyglactin mesh - Aluminium oxide as an implant material is gaining popularity due to its relative lower cost, as well as suggested excellent biocompatibility. Hydroxyapatite implants - These are porous tissue integrated implant which allow infiltration of fibrovascular tissues. - These are wrapped with donor sclera,and the extraocular muscles are anchored to the implant. - Tissue integration of these implants minimizes the risk of migration and extrusion, hence preferred in enucleation cases where socket has contracted/shrunken. - Actual pegging of the implant is performed invivo after 6 months’ time and the prosthesis is placed on top of the peg to improve motility Polyethylene (MEDPOR) - It is also porous form of tissue integrated orbital implant that allows fibrovascular ingrowth - It does not require donor sclera. Its cost is low in comparison to hydroxyapatite, and the extraocular muscles are directly sutured to the implant. Dermal fat graft (DFG) - Is an alternate to ocular implants for volume augmentation in patients with volume loss, contracted sockets and implant extrusion - Fat from around the navel or buttock is used to fill space formerly occupied by the eye - Muscles cannot be attached to a fat graft. - There is no risk of rejection as this graft uses the patient’s own tissue. These grafts are often the best option when a material implant is exposed or infected. - Major advantage in children is fat grafts grow with the child, matching growth of the other eye - Fat to restore orbital volume and dermis that provides vascular support for the graft < 3 years of age - Who undergo enucleation, most of the surgeons prefer dermis fat graft (DFG) as primary ocular implant. - Because at age of 3 or less, orbit still needs to undergo significant growth 3-6 years of age - DFG is still the preferred > 6 years of age - Porous implants are preferred - DFG can still be used but orbital growth is less of concern

Among the given options, best answer to mark is Option D only - If they had asked "Oblique" facial cleft, then answer would have been Option C - If they had asked, Median Cleft of upper lip, then answer would have been option A, which itself is very rare - Defective fusion of the medial nasal process with the maxillary process leads to cleft lip (CL) (Merging of the medial nasal processes to form the Intermaxillary segment) - Frequency: (CL+CP) >> (CPO - Cleft Palate only) >> (CLO - Cleft Lip only) - Most of cleft lips are unilateral and more common on left side (Cleft on left is the mnemonic) - Minimal manifestation of CP is a bifid uvula Unilateral cleft lip (Most common) - Due to failure of fusion of median nasal process (inter-maxillary segment) with maxillary process at 5th week of intrauterine life Median cleft of upper lip - Due to non-fusion of median nasal processes - Associated with: Oro-facial-digital syndrome and Ellis-van Creveld syndrome Oblique facial cleft - Failure of fusion between lateral nasal process and maxillary process - Cleft is along nasolacrimal groove nasolacrimal duct is absent - Runs from median angle of eye to corner of mouth Lateral facial cleft - Failure of fusion of maxillary with mandibular processes, causing macrostomia - Associated with other disorders- (Neville) - Mandibulofacial dysostosis - Hemifacial microsomia (Oculo-auriculo-vertebral) - Nager acrofacial dysostosis - Amniotic rupture sequence Submucous palatal cleft - Surface mucosa is intact, but underlying musculature of the soft palate shows cleft

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