p.1
Glossary of Dermatopathology Terms
What is Acantholysis?
Loss of cell–cell adhesion.
p.1
Glossary of Dermatopathology Terms
What does Acanthosis refer to?
Increase in thickness of the epidermis, which can be regular or irregular.
p.29
Markers for Tumor Identification
What is CD7 and its significance in T-cell lymphoma?
CD7 is an immature T-lymphocyte antigen and is the most commonly lost antigen in T-cell lymphoma.
p.29
Markers for Tumor Identification
What does CD56 indicate?
CD56 is a marker of NK cells and subsets of T cells.
p.1
Glossary of Dermatopathology Terms
What is Apoptosis?
Programmed cell death, characterized by 'dead red' keratinocytes with pyknotic nuclei.
p.18
Histochemical Stains and Their Applications
What is a significant pitfall when using Masson’s trichrome stain?
Very young collagen can stain red.
p.15
Skin Anatomy and Structure
What are the key features of nail anatomy?
Nail plate, nail bed, proximal nail fold, lateral nail folds, distal nail fold, cuticle, hyponychium, solehorn.
p.2
Histological Features of Skin Conditions
What characterizes ballooning degeneration?
Destruction of the epidermis by dissolution of cell attachments and intracellular edema.
p.5
Glossary of Dermatopathology Terms
What is follicular mucinosis?
Alteration of hair sheath anatomy by pools of mucin.
p.5
Glossary of Dermatopathology Terms
What characterizes granulomatous conditions?
Composed of granulomas (collections of histiocytes).
p.17
Inflammatory Cells in Dermatopathology
What are the key features of lymphocytes?
Round dark nucleus, generally with no visible cytoplasm; B-cells produce antibodies; NK cells are part of the innate immune system; T-cells mature in the thymus and are important for cell-mediated immunity.
p.5
Glossary of Dermatopathology Terms
What are Guarnieri bodies?
Eosinophilic inclusions of smallpox.
p.13
Types of Keratinization
What type of keratinization occurs in the absence of a granular layer?
Trichilemmal keratinization.
p.1
Glossary of Dermatopathology Terms
What are Asteroid bodies?
Collections of eosinophilic material seen in sporotrichosis, or star-shaped intracytoplasmic inclusions in giant cells of granulomatous processes.
p.30
Markers for Tumor Identification
What is the significance of CD43 (Leu-22) in dermatopathology?
It is a Pan-T-cell marker; aberrant coexpression with CD20 suggests B-cell lymphoma.
p.17
Inflammatory Cells in Dermatopathology
What do mast cells contain?
Metachromatic granules composed of heparin, histamine, tryptase, carboxypeptidase, and leukotrienes.
p.18
Histochemical Stains and Their Applications
What does Toluidine blue stain in mast cells?
Mast cell granules metachromatically, resulting in blue dye but purple granules.
p.13
Types of Skin Lesions and Their Characteristics
What type of hair can dermatophytes infect?
Cornified hair above Adamson's fringe.
p.14
Skin Anatomy and Structure
What does a vertical section of hair show in dermatopathology?
It provides insights into the structure and characteristics of hair follicles.
p.15
Skin Anatomy and Structure
Where is the true cuticle located?
Beneath the visible cuticle, derived from the ventral part of the proximal nail fold.
p.13
Skin Anatomy and Structure
What is the key feature of the isthmus in hair follicles?
It extends from the insertion of the sebaceous gland to the insertion of the arrector pili muscle (bulge).
p.16
Types of Keratinization
Where does Epidermoid keratinization occur?
In the dorsal proximal nail fold, lateral folds, and hyponychium.
p.10
Skin Anatomy and Structure
What are key features of scalp skin?
Numerous follicles that extend down into the panniculus, associated sebaceous glands, and arrector pili muscles.
p.9
Glossary of Dermatopathology Terms
What characterizes the spongiform pustule of Kogoj?
Neutrophils in the stratum spinosum, associated with spongiosis at the periphery, typical of psoriasis.
p.10
Skin Anatomy and Structure
What characterizes facial skin?
Thin epidermis, basket-weave stratum corneum, numerous hair follicles and sebaceous glands, and common presence of Demodex mites.
p.3
Histological Features of Skin Conditions
What characterizes cornoid lamellae?
45° angle parakeratosis in a column above a focus with a diminished granular layer and underlying dyskeratotic cells.
p.16
Inflammatory Cells in Dermatopathology
What distinguishes Langhans giant cells?
Their nuclei are arranged in a wreath shape.
p.7
Histological Features of Skin Conditions
What is a Munro microabscess?
A collection of neutrophils in the stratum corneum, as seen in psoriasis.
p.3
Glossary of Dermatopathology Terms
What does dyskeratosis refer to?
Abnormal, individual-cell keratinization.
p.16
Inflammatory Cells in Dermatopathology
What are the characteristics of a histiocyte?
An epithelioid cell with a central nucleus, derived from monocytes, involved in phagocytosis and antigen presentation.
p.11
Skin Anatomy and Structure
What structures are absent in volar skin?
Hair follicles and sebaceous glands.
p.9
Glossary of Dermatopathology Terms
What is a Verocay body?
A structure composed of two nuclear palisades enclosing pink cytoplasmic processes, seen in schwannoma.
p.25
Immunohistochemical Techniques
What does Epithelial membrane antigen (EMA) highlight?
Normal sebaceous and sweat glands.
p.22
Histochemical Stains and Their Applications
What is a unique feature of the Fite stain?
It preserves color due to the use of peanut oil before staining.
p.6
Glossary of Dermatopathology Terms
What is a Kamino body?
Dull pink to amphophilic basement membrane material within the epidermis in a Spitz nevus.
p.28
Markers for Tumor Identification
What is CD45Ra (LCA) a marker for?
Hematolymphoid differentiation.
p.28
Markers for Tumor Identification
Which cells do not express LCA?
Maturing erythroids and megakaryocytes.
p.2
Histological Features of Skin Conditions
What is atrophy in dermatopathology?
A decrease in thickness of the epidermis.
p.29
Markers for Tumor Identification
What is the role of CD68 (KP-1) in immunology?
CD68 (KP-1) is reactive in virtually all monocyte/macrophage cells.
p.4
Histological Features of Skin Conditions
What is a characteristic feature of epidermolytic hyperkeratosis?
Coarse, irregular hypergranulosis associated with disruption of cell membranes.
p.11
Skin Anatomy and Structure
What structures may be found in areolar skin?
A central invagination of the epidermis leading to a follicle and sebaceous glands.
p.12
Histological Features of Skin Conditions
What are the key features of nasal turbinate?
Erectile tissue with fibrous septa and vascular sinusoids, along with mucous glands.
p.16
Inflammatory Cells in Dermatopathology
What are the key features of a giant cell?
A cell with multiple nuclei and usually abundant cytoplasm.
p.29
Markers for Tumor Identification
What does a 10-fold deviation from the kappa/lambda ratio suggest?
It suggests a clonal B-cell proliferation.
p.11
Skin Anatomy and Structure
What characterizes acral skin?
Compact eosinophilic stratum corneum.
p.16
Inflammatory Cells in Dermatopathology
What is a Touton giant cell?
A giant cell with nuclei arranged in a wreath and foamy cytoplasm peripherally.
p.30
Histological Features of Skin Conditions
What is MIB-1 (Ki-67) used for in dermatopathology?
It is a proliferation marker and a more sensitive indicator of cell proliferation than mitotic figures.
p.9
Glossary of Dermatopathology Terms
What does storiform describe?
A cartwheel or basket-weave pattern.
p.10
Skin Anatomy and Structure
What happens to fat projections in the skin of the trunk?
Projections of fat extend upward to envelop adnexae.
p.6
Glossary of Dermatopathology Terms
What does hyperpigmentation refer to in dermatopathology?
Increased melanin pigment.
p.19
Histochemical Stains and Their Applications
What type of mucin is predominantly found in normal skin?
Sulfated acid mucosaccharides.
p.18
Histochemical Stains and Their Applications
What does Masson’s trichrome stain differentiate?
Collagen (blue-green) from smooth muscle (red).
p.20
Histochemical Stains and Their Applications
How does Toluidine blue compare to Alcian blue in terms of complexity?
Toluidine blue is technically more complicated and used less often.
p.1
Glossary of Dermatopathology Terms
What does the term Arborizing refer to?
Branching, often related to rete or vasculature.
p.16
Inflammatory Cells in Dermatopathology
What are dermal dendrocytes?
Macrophage-type cells located in the dermis that may serve as antigen-presenting cells.
p.18
Histochemical Stains and Their Applications
What conditions can be identified using Verhoeff–Van Gieson stain?
Absence or reduction in scar, mid dermal elastolysis, anetoderma, cutis laxa.
p.13
Skin Anatomy and Structure
What is Adamson's fringe?
The point above which hair cornifies.
p.15
Skin Anatomy and Structure
What is the lunula?
The visible portion of the nail matrix.
p.23
Histochemical Stains and Their Applications
What type of microscope is required for Auramine-rhodamine staining?
A fluorescent microscope.
p.9
Glossary of Dermatopathology Terms
What are squamous eddies?
Circular whorls of squamous cells.
p.10
Skin Anatomy and Structure
What are the key features of the skin of the trunk?
Very thick dermis, especially in skin from the back, scattered hair follicles, and sebaceous glands.
p.12
Types of Keratinization
How does the infundibulum keratinize?
In the pattern of normal epidermis with a granular layer (keratohyaline granules).
p.9
Glossary of Dermatopathology Terms
What is vacuolar change?
Formation of clear spaces within the basal layer.
p.8
Glossary of Dermatopathology Terms
What is pigment incontinence?
Melanin within dermal macrophages.
p.24
Markers for Tumor Identification
What does the AE1/AE3 marker stain?
All epithelial tumors, including squamous cell carcinoma and adnexal tumors.
p.30
Histological Features of Skin Conditions
What is the significance of distinguishing MIB-1-positive melanocytes?
Positive background reactive lymphocytes must be distinguished from MIB-1-positive melanocytes by cytology or double staining technique.
p.3
Markers for Tumor Identification
What is a Dutcher body?
Intracytoplasmic pink masses of immunoglobulin that invaginate into the nucleus of plasma cells.
p.23
Histochemical Stains and Their Applications
What does Giemsa stain highlight?
Myeloid and mast cell granules in purplish blue.
p.23
Histochemical Stains and Their Applications
What types of organisms can Giemsa stain identify?
Bacteria, Leishmania, and Histoplasma.
p.28
Markers for Tumor Identification
What does loss of CD45Rb staining indicate?
Epidermotropic T cells in mycosis fungoides.
p.23
Immunohistochemical Techniques
What is the DAB method used for in immunohistochemistry?
To visualize the presence of enzyme–antibody–antigen complex as a stable brown product.
p.26
Markers for Tumor Identification
What condition shows increased staining of CD34?
Nephrogenic systemic fibrosis.
p.26
Markers for Tumor Identification
What does Factor XIIIa highlight?
A population of dermal dendritic cells.
p.1
Glossary of Dermatopathology Terms
What is Anaplasia characterized by?
Atypical nuclei and pleomorphism.
p.5
Glossary of Dermatopathology Terms
What is the Grenz zone?
An uninvolved area of dermis beneath the epidermis or adjacent to a hair follicle.
p.2
Histological Features of Skin Conditions
What does the caterpillar body represent?
Pale pink linear basement membrane material within the epidermis, seen in porphyria cutanea tarda, representing degenerated type IV collagen.
p.29
Markers for Tumor Identification
What does ALK-1 indicate in anaplastic large cell lymphoma?
ALK-1 indicates anaplastic lymphoma kinase expressing chromosomal translocation t(2,5) and is positive in most systemic anaplastic large cell lymphoma.
p.15
Skin Anatomy and Structure
What does the nail matrix consist of?
The proximal part makes the surface of the nail; the distal part makes the ventral nail plate.
p.12
Histological Features of Skin Conditions
What characterizes fetal skin?
Stellate and spindled fibroblasts (mesenchyme) and densely cellular.
p.18
Histochemical Stains and Their Applications
What does the Leder stain (naphthol ASD chloroacetate esterase) stain?
Mast cell cytoplasm red, independent of granules, and also stains myeloid cells.
p.13
Skin Anatomy and Structure
What are the three zones of the hair bulb?
Matrix, supramatrix, and keratogenous zone.
p.7
Glossary of Dermatopathology Terms
What are Negri bodies?
Inclusions within neurons seen in rabies infection.
p.3
Markers for Tumor Identification
What are Cowdry B bodies?
Intranuclear pink inclusions associated with adenovirus and poliovirus infection.
p.19
Histochemical Stains and Their Applications
What does Alcian blue stain?
Acid mucosaccharides blue.
p.7
Histological Features of Skin Conditions
What does pagetoid scatter refer to?
Buckshot scatter of atypical cells within the epidermis.
p.30
Types of Skin Lesions and Their Characteristics
What does a positive CK stain indicate in Paget’s disease?
It indicates the presence of intraepidermal buckshot scatter (pagetoid spread).
p.3
Histological Features of Skin Conditions
What does effacement refer to in dermatopathology?
Loss of normal rete pattern.
p.27
Immunohistochemical Techniques
Which cells does S100 specifically stain?
Melanocytes, Langerhans cells, sweat glands, nerves, Schwann cells, myoepithelial cells, fat, muscles, and chondrocytes.
p.26
Markers for Tumor Identification
What does CD34 mark in dermatopathology?
Vascular endothelium and hematopoietic progenitor cells.
p.26
Markers for Tumor Identification
In which condition is CD34 positive?
Dermatofibrosarcoma protuberans.
p.6
Glossary of Dermatopathology Terms
What is a lentiginous melanocytic growth pattern?
Proliferation predominantly along the dermal-epidermal junction.
p.20
Histochemical Stains and Their Applications
What is the staining pattern of Toluidine blue?
Metachromatic (reddish purple) similar to Alcian blue.
p.9
Glossary of Dermatopathology Terms
What is a Schaumann body?
A laminated calcified structure seen in sarcoidosis.
p.15
Skin Anatomy and Structure
What is the hyponychium?
The space, epithelium, and keratinous material ventral to the nail plate.
p.2
Histological Features of Skin Conditions
What are Civatte/colloid bodies?
Pink, globular remnants of keratinocytes.
p.4
Inflammatory Cells in Dermatopathology
What does epidermotropism refer to?
Lymphocytes in the epidermis with relative absence of spongiosis, usually reserved for mycosis fungoides.
p.20
Histochemical Stains and Their Applications
What is required to examine sections stained with Thioflavin T?
A fluorescent microscope, revealing a yellow to yellow-green appearance.
p.12
Skin Anatomy and Structure
What is the infundibulum in hair anatomy?
It extends from the epidermis down to the insertion of the sebaceous gland.
p.20
Histochemical Stains and Their Applications
What does Iron Prussian blue (Perls stain) reveal?
Ferric ions form a deep blue, useful for distinguishing melanin from hemosiderin.
p.24
Immunohistochemical Techniques
What is the purpose of immunopathologic antibodies in dermatopathology?
To differentiate carcinoma, melanoma, sarcoma, neural neoplasms, and lymphomas.
p.13
Skin Anatomy and Structure
What distinguishes anagen hairs from telogen hairs?
Anagen hairs have a stem and bulb that produce the hair shaft, while telogen hairs lack an inferior segment.
p.8
Glossary of Dermatopathology Terms
What is parakeratosis?
Stratum corneum with retained nuclei.
p.24
Immunohistochemical Techniques
What should be assessed to ensure proper reactivity of antibodies?
Independent and internal controls.
p.30
Diagnostic Techniques in Dermatopathology
What transport media is preferred for immunofluorescence?
Michel’s medium (ammonium sulfate) or normal saline.
p.3
Markers for Tumor Identification
What is a Donovan body?
Intracytoplasmic collections of bacteria seen in granuloma inguinale.
p.28
Markers for Tumor Identification
What does Synaptophysin indicate?
Positive in Merkel cell carcinoma.
p.19
Histochemical Stains and Their Applications
At what pH do nonsulfated acid mucosaccharides stain with Alcian blue?
pH 2.5 but not at pH 0.5.
p.19
Histochemical Stains and Their Applications
How does colloidal iron staining work?
Colloidal iron binds to acid mucosaccharides, and Prussian blue stains the iron.
p.8
Glossary of Dermatopathology Terms
What are Russell bodies?
Intracytoplasmic pink collections of immunoglobulins in plasma cells.
p.25
Immunohistochemical Techniques
What are examples of conditions where SMA is positive?
Glomus tumor and leiomyosarcoma.
p.6
Glossary of Dermatopathology Terms
What is a Medlar body?
A brown, round structure resembling overlapping copper pennies, divided by septation.
p.16
Types of Keratinization
What is Onychokeratinization?
A type of keratinization of the nail plate that lacks a granular layer.
p.16
Types of Keratinization
What characterizes Onycholemmal keratinization?
It involves the ventral part of the proximal nail fold and includes a granular layer.
p.29
Markers for Tumor Identification
What is myeloperoxidase and its relevance in leukemia?
Myeloperoxidase is a major constituent of granules of neutrophilic myeloid cells and serves as a marker for acute myeloid leukemia.
p.17
Inflammatory Cells in Dermatopathology
What is the appearance of mast cells?
They have a 'fried-egg' appearance with a central round nucleus and surrounding oval, bluish cytoplasm.
p.7
Histochemical Stains and Their Applications
What is metachromasia?
The property of staining a different color from the stain itself, such as the purple color of mast cell granules with methylene blue.
p.9
Glossary of Dermatopathology Terms
What is spongiosis?
Intercellular edema in the epidermis with stretching of cell–cell junctions.
p.10
Skin Anatomy and Structure
What is unique about the eyelid and ear skin?
They have many vellus hair follicles and skeletal muscle bundles in the upper dermis.
p.3
Glossary of Dermatopathology Terms
What is a corps rond?
A rounded nucleus with a halo of pale to pink dyskeratotic cytoplasm.
p.8
Glossary of Dermatopathology Terms
What does the papillary mesenchymal body resemble?
A whorl of plump mesenchymal cells normally present in the hair papilla.
p.7
Histological Features of Skin Conditions
What does necrobiosis refer to?
Pale-staining smudged necrotic collagen.
p.3
Markers for Tumor Identification
What are Cowdry A bodies?
Intranuclear pink inclusions associated with herpesvirus infection.
p.16
Inflammatory Cells in Dermatopathology
What defines a Langerhans cell?
Dendritic cells in the epidermis and dermis that present antigens to T cells and contain Birbeck granules.
p.10
Histological Features of Skin Conditions
What is solar elastosis?
A condition where sun-damaged skin spares the papillary dermis.
p.6
Glossary of Dermatopathology Terms
What is the interface in dermatopathology?
Generally refers to the dermoepidermal junction.
p.23
Histochemical Stains and Their Applications
Which diseases can be identified using Dieterle stain?
Lyme disease and syphilis.
p.25
Immunohistochemical Techniques
How does EMA react in squamous cell carcinoma compared to basal cell carcinoma?
Positive in squamous cell carcinoma but negative in basal cell carcinoma.
p.25
Immunohistochemical Techniques
What is Carcinoembryonic antigen (CEA) positive in?
Sweat gland neoplasms, Paget’s disease, extramammary Paget’s, and most adenocarcinomas.
p.8
Glossary of Dermatopathology Terms
What is reticular degeneration?
Destruction of epidermis with cell membranes remaining in a net-like pattern.
p.23
Immunohistochemical Techniques
What alternative reagent can be used in immunohistochemistry for a red reaction?
3-Amino-9-ethylcarbazole (AEC).
p.6
Glossary of Dermatopathology Terms
What is leukocytoclasia?
Fragmentation of neutrophils, also referred to as karyorrhexis.
p.26
Markers for Tumor Identification
What tumors does CD34 typically highlight?
The stroma of trichoepitheliomas but not basal cell carcinomas.
p.18
Histochemical Stains and Their Applications
What is the routine staining choice for microscopic interpretation in dermatopathology?
A mixture of hematoxylin and eosin (H&E), resulting in blue nuclei and pink cytoplasm.
p.12
Histological Features of Skin Conditions
What characterizes keratinocytes in the mucosa?
They are large and pale, filled with glycogen.
p.11
Skin Anatomy and Structure
What is a key feature of areolar skin?
Slight acanthosis of the epidermis with basilar hyperpigmentation.
p.17
Inflammatory Cells in Dermatopathology
What is the role of B-cell lymphocytes?
They produce antibodies and are important for humoral immunity.
p.4
Histological Features of Skin Conditions
Which keratin mutations are associated with epidermolytic hyperkeratosis?
Keratin 1 and 10 mutations.
p.20
Histochemical Stains and Their Applications
What color does amyloid stain with Congo red?
Brick red, displaying 'apple-green' birefringence with polarized light.
p.29
Markers for Tumor Identification
What is the normal expression ratio of kappa to lambda light chains?
The normal expression ratio is two-thirds kappa to one-third lambda.
p.5
Glossary of Dermatopathology Terms
What does hypogranulosis indicate?
Decreased granular layer.
p.30
Markers for Tumor Identification
In which lymphomas is BCL2 positive?
Nodal follicular center cell lymphomas with chromosomal translocation.
p.4
Histological Features of Skin Conditions
What is festooning in dermatopathology?
Papillary dermis retains an undulating pattern, often used to describe porphyria cutanea tarda.
p.22
Histochemical Stains and Their Applications
Which organisms can also be stained by GMS besides fungi?
Nocardia and Actinomyces.
p.19
Histochemical Stains and Their Applications
In which conditions is PAS staining useful?
Clear cell acanthoma, trichilemmoma, tinea corporis, tinea versicolor, Candida, lupus erythematosus, and porphyria.
p.7
Histological Features of Skin Conditions
What are pagetoid cells?
Large cells with abundant cytoplasm within the epidermis.
p.27
Immunohistochemical Techniques
What does Vimentin stain?
Mesenchymal cells, endothelial cells, fibroblasts, melanocytes, lymphocytes, and macrophages.
p.21
Histochemical Stains and Their Applications
What is the Fontana–Masson stain used for?
It is a silver stain that results in a black precipitate with melanin.
p.8
Glossary of Dermatopathology Terms
What is pseudoepitheliomatous hyperplasia (PEH)?
Prominent acanthosis of the adnexal epithelium and epidermis that mimics squamous cell carcinoma.
p.8
Glossary of Dermatopathology Terms
What characterizes a pseudohorn cyst?
A keratin-filled cystic structure that connects to the surface.
p.23
Immunohistochemical Techniques
What is the role of antibodies in immunohistochemical stains?
They are directed towards the antigen of interest and conjugated to peroxidases.
p.28
Markers for Tumor Identification
What is the significance of CD20 loss?
Correlates with rituximab resistance.
p.21
Histochemical Stains and Their Applications
What is a common requirement for stains like Sudan black and osmium tetroxide?
They require fresh tissue.
p.28
Markers for Tumor Identification
What is CD30 originally identified on?
Reed–Sternberg cells of Hodgkin’s disease.
p.10
Glossary of Dermatopathology Terms
What is a villus in dermatopathology?
A projection of the papillary dermis covered by a layer of epidermal cells into a cavity.
p.20
Histochemical Stains and Their Applications
What does Mucicarmine stain?
Acid mucosaccharides pink to red, including the mucinous capsule of Cryptococcus neoformans.
p.5
Glossary of Dermatopathology Terms
What are Henderson–Paterson bodies?
Intracytoplasmic oval, pink inclusions of molluscum infection.
p.3
Histological Features of Skin Conditions
What is collagen entrapment?
Collagen fibers surrounded by histiocytes or spindle cells, also known as collagen balls.
p.22
Histochemical Stains and Their Applications
What is the significance of PAS-positive and diastase-resistant staining?
It indicates the presence of certain fungi.
p.7
Glossary of Dermatopathology Terms
What are Michaelis–Gutman bodies?
Intra- and extracellular calcified, concentric circular structures seen in malakoplakia.
p.4
Inflammatory Cells in Dermatopathology
What does exocytosis indicate in dermatopathology?
Lymphocytes in the epidermis with associated spongiosis, usually used when discussing spongiotic dermatitis.
p.22
Histochemical Stains and Their Applications
What does Grocott’s methenamine silver (GMS) stain reveal?
A gray-black reaction with the fungal wall.
p.17
Inflammatory Cells in Dermatopathology
What is the appearance of plasma cells?
They have an eccentric nucleus with a 'clock face' and a perinuclear pale space corresponding to rough endoplasmic reticulum.
p.4
Histological Features of Skin Conditions
What is a flame figure?
Collagen encrusted with major basic protein from eosinophils.
p.3
Types of Skin Lesions and Their Characteristics
What is a crust in dermatopathology?
Serum or fluid with inflammatory cells and debris in the stratum corneum.
p.25
Immunohistochemical Techniques
In which conditions is EMA positive?
Sebaceous carcinoma, Paget’s disease, and extramammary Paget’s.
p.22
Histochemical Stains and Their Applications
What types of organisms can be identified using the Fite stain?
Partially acid-fast organisms such as lepra bacilli and atypical mycobacteria.
p.27
Immunohistochemical Techniques
What does S100 stain?
Neural crest-derived cells and some mesenchymal lines.
p.6
Glossary of Dermatopathology Terms
What are koilocytes?
Keratinocytes with clear cytoplasm and shrunken 'raisin-like' pyknotic nuclei.
p.6
Glossary of Dermatopathology Terms
What are Leishman–Donovan bodies?
Intracytoplasmic collections of amastigotes in leishmaniasis.
p.26
Markers for Tumor Identification
What does CD34 stain around in normal skin?
Connective tissue around normal hair follicles.
p.26
Markers for Tumor Identification
In which condition is Factor XIIIa negative?
Dermatofibrosarcoma protuberans.
p.9
Glossary of Dermatopathology Terms
What are shadow cells?
Cells with barely visible outlines of nuclei.
p.15
Skin Anatomy and Structure
What is the solehorn?
Subungual white to colorless keratin extending from the distal nail bed to below the free edge of the nail plate.
p.13
Skin Anatomy and Structure
What happens to the inner root sheath at the isthmus level?
It is lost, and the outer root sheath develops a dense pink cornified layer.
p.5
Glossary of Dermatopathology Terms
What does hypergranulosis indicate?
Increased granular layer.
p.30
Markers for Tumor Identification
What role does BCL2 play in cancer?
It is an oncogene that inhibits apoptosis.
p.9
Glossary of Dermatopathology Terms
What does squamotization refer to?
Loss of cuboidal/columnar basal cells, with the deepest layer now being polyhedral, pink squamous cells.
p.10
Skin Anatomy and Structure
What is absent on the conjunctival surface of the eyelid?
Stratum corneum and hair follicles, but goblet cells are present.
p.20
Histochemical Stains and Their Applications
What does Iron Prussian blue not demonstrate?
Iron in intact red blood cells.
p.19
Histochemical Stains and Their Applications
What happens to glycogen when exposed to diastase before PAS staining?
It does not stain red with the PAS reaction.
p.13
Types of Skin Lesions and Their Characteristics
How can telogen hairs be recognized in vertical sections?
By the club hair and surrounding trichilemmal keratin, which give the impression of a flame thrower.
p.8
Glossary of Dermatopathology Terms
What does pleomorphism refer to?
Variation in nuclear size and shape.
p.24
Markers for Tumor Identification
What is the advantage of using CK Polyclonal keratin (pankeratin)?
It offers greater sensitivity than AE1/AE3.
p.27
Markers for Tumor Identification
What is Vimentin a general marker for?
Sarcomas, excluding most carcinomas.
p.21
Histochemical Stains and Their Applications
What does the Von Kossa stain target?
It stains calcium salts black.
p.21
Histochemical Stains and Their Applications
What conditions can be identified using the Von Kossa stain?
Pseudoxanthoma elasticum, calcinosis cutis, and calciphylaxis.
p.27
Immunohistochemical Techniques
What is HMB-45 used for?
Staining melanocytic lesions.
p.27
Markers for Tumor Identification
What does a loss of HMB-45 staining indicate?
Loss of premelanosomes and normal maturation.
p.25
Immunohistochemical Techniques
How does Smooth-muscle actin (SMA) react in smooth muscle?
Positive in smooth muscle, including vascular smooth muscle.
p.27
Markers for Tumor Identification
Why is NSE sometimes referred to as 'nonspecific enolase'?
Because it is positive in many other cell lines.
p.28
Markers for Tumor Identification
What can CD20 positivity indicate in intravascular lymphoma?
Presence of B-cell antigen.
p.17
Inflammatory Cells in Dermatopathology
What is the key feature of eosinophils?
They have a bilobed nucleus with granular cytoplasm containing major basic protein and eosinophil cationic protein.
p.19
Histochemical Stains and Their Applications
What does Periodic acid–Schiff (PAS) stain?
Glycogen, neutral mucopolysaccharides, and fungi red.
p.11
Skin Anatomy and Structure
What is a key feature of volar skin?
Compact eosinophilic hyperkeratosis with underlying stratum lucidum.
p.24
Immunohistochemical Techniques
Why is a panel of antibodies recommended over a single stain?
Because aberrant staining is common in neoplasms.
p.7
Skin Anatomy and Structure
What is orthokeratosis?
Increased thickness of the stratum corneum without retained nuclei.
p.27
Immunohistochemical Techniques
What is Ulex europeus?
A lectin that binds epithelium and endothelium.
p.11
Skin Anatomy and Structure
Which sensory corpuscles may be seen in volar skin?
Meissner and Pacinian corpuscles.
p.8
Glossary of Dermatopathology Terms
What are psammoma bodies?
Extracellular laminated, calcified structures seen in certain carcinomas.
p.7
Histological Features of Skin Conditions
What is palisading?
A picket fence-like arrangement at the periphery.
p.6
Glossary of Dermatopathology Terms
What is karyorrhexis?
Fragmentation of neutrophils, also known as leukocytoclasis.
p.24
Markers for Tumor Identification
What does CK20 predominantly mark?
Merkel cell carcinoma in a paranuclear pattern.
p.21
Histochemical Stains and Their Applications
What is required for the Oil red O stain to work effectively?
Fresh frozen tissue, as lipid is removed during processing.
p.28
Markers for Tumor Identification
What does CD8 represent?
T-cell cytotoxic/suppressor marker.
p.26
Markers for Tumor Identification
What is the significance of CD31 in dermatopathology?
Helpful in confirming vascular origin of tumors.
p.24
Markers for Tumor Identification
What does CAM5.2 detect?
Low-molecular-weight cytokeratins present in most glandular neoplasms.
p.24
Markers for Tumor Identification
What is CK7 used for?
Determining the origin of metastatic carcinoma, particularly nongastrointestinal adenocarcinoma.
p.25
Immunohistochemical Techniques
What does Ber-EP4 mark?
Most epithelial cells, but not those undergoing squamous differentiation.
p.24
Markers for Tumor Identification
How does CK20 help in distinguishing tumors?
It distinguishes Merkel cell carcinoma from metastatic oat cell carcinoma of the lung, which is typically negative.
p.25
Immunohistochemical Techniques
What does Desmin stain positive in?
Skeletal and most smooth muscle.
p.27
Markers for Tumor Identification
What is Neuron-specific enolase (NSE) positive in?
Neuroendocrine cells, neurons, and tumors derived from them.
p.6
Glossary of Dermatopathology Terms
What is a lichenoid infiltrate?
A band-like infiltrate, generally composed predominantly of lymphocytes, located at the dermoepidermal junction.
p.26
Markers for Tumor Identification
How does CD31 compare to CD34?
CD31 is a more specific vascular marker than CD34.
p.3
Histological Features of Skin Conditions
What is eosinophilic spongiosis?
Spongiosis with eosinophils in the epidermis.
p.21
Histochemical Stains and Their Applications
What does the Brown–Hopps stain differentiate between?
It differentiates between Gram-positive organisms (stain blue) and Gram-negative organisms (stain red).
p.28
Markers for Tumor Identification
What type of marker is CD4?
T-helper lymphocytic marker.
p.28
Markers for Tumor Identification
In which conditions is CD30 positive?
Anaplastic large cell lymphoma and lymphomatoid papulosis.
p.6
Glossary of Dermatopathology Terms
What is lichenoid dermatitis?
Interface dermatitis with destruction of the basal layer and Civatte body formation.
